/*

  * Copyright (c) 1995, 2011, Oracle and/or its affiliates. All rights reserved.

  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

  *

  * This code is free software; you can redistribute it and/or modify it

  * under the terms of the GNU General Public License version 2 only, as

  * published by the Free Software Foundation.  Oracle designates this

  * particular file as subject to the "Classpath" exception as provided

  * by Oracle in the LICENSE file that accompanied this code.

  *

  * This code is distributed in the hope that it will be useful, but WITHOUT

  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

  * version 2 for more details (a copy is included in the LICENSE file that

  * accompanied this code).

  *

  * You should have received a copy of the GNU General Public License version

  * 2 along with this work; if not, write to the Free Software Foundation,

  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

  *

  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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 package java.net;

 import java.io.IOException;

 import java.io.InputStream;

 import java.io.OutputStream;

 import java.util.Hashtable;

 import java.util.Date;

 import java.util.StringTokenizer;

 import java.util.Collections;

 import java.util.Map;

 import java.util.List;

 import java.security.Permission;

 import java.security.AccessController;

 import sun.security.util.SecurityConstants;

 import sun.net.www.MessageHeader;

 /**

  * The abstract class <code>URLConnection</code> is the superclass

  * of all classes that represent a communications link between the

  * application and a URL. Instances of this class can be used both to

  * read from and to write to the resource referenced by the URL. In

  * general, creating a connection to a URL is a multistep process:

  * <p>

  * <center><table border=2 summary="Describes the process of creating a connection to a URL: openConnection() and connect() over time.">

  * <tr><th><code>openConnection()</code></th>

  *     <th><code>connect()</code></th></tr>

  * <tr><td>Manipulate parameters that affect the connection to the remote

  *         resource.</td>

  *     <td>Interact with the resource; query header fields and

  *         contents.</td></tr>

  * </table>

  * ---------------------------->

  * <br>time</center>

  *

  * <ol>

  * <li>The connection object is created by invoking the

  *     <code>openConnection</code> method on a URL.

  * <li>The setup parameters and general request properties are manipulated.

  * <li>The actual connection to the remote object is made, using the

  *    <code>connect</code> method.

  * <li>The remote object becomes available. The header fields and the contents

  *     of the remote object can be accessed.

  * </ol>

  * <p>

  * The setup parameters are modified using the following methods:

  * <ul>

  *   <li><code>setAllowUserInteraction</code>

  *   <li><code>setDoInput</code>

  *   <li><code>setDoOutput</code>

  *   <li><code>setIfModifiedSince</code>

  *   <li><code>setUseCaches</code>

  * </ul>

  * <p>

  * and the general request properties are modified using the method:

  * <ul>

  *   <li><code>setRequestProperty</code>

  * </ul>

  * <p>

  * Default values for the <code>AllowUserInteraction</code> and

  * <code>UseCaches</code> parameters can be set using the methods

  * <code>setDefaultAllowUserInteraction</code> and

  * <code>setDefaultUseCaches</code>.

  * <p>

  * Each of the above <code>set</code> methods has a corresponding

  * <code>get</code> method to retrieve the value of the parameter or

  * general request property. The specific parameters and general

  * request properties that are applicable are protocol specific.

  * <p>

  * The following methods are used to access the header fields and

  * the contents after the connection is made to the remote object:

  * <ul>

  *   <li><code>getContent</code>

  *   <li><code>getHeaderField</code>

  *   <li><code>getInputStream</code>

  *   <li><code>getOutputStream</code>

  * </ul>

  * <p>

  * Certain header fields are accessed frequently. The methods:

  * <ul>

  *   <li><code>getContentEncoding</code>

  *   <li><code>getContentLength</code>

  *   <li><code>getContentType</code>

  *   <li><code>getDate</code>

  *   <li><code>getExpiration</code>

  *   <li><code>getLastModifed</code>

  * </ul>

  * <p>

  * provide convenient access to these fields. The

  * <code>getContentType</code> method is used by the

  * <code>getContent</code> method to determine the type of the remote

  * object; subclasses may find it convenient to override the

  * <code>getContentType</code> method.

  * <p>

  * In the common case, all of the pre-connection parameters and

  * general request properties can be ignored: the pre-connection

  * parameters and request properties default to sensible values. For

  * most clients of this interface, there are only two interesting

  * methods: <code>getInputStream</code> and <code>getContent</code>,

  * which are mirrored in the <code>URL</code> class by convenience methods.

  * <p>

  * More information on the request properties and header fields of

  * an <code>http</code> connection can be found at:

  * <blockquote><pre>

  * <a href="http://www.ietf.org/rfc/rfc2616.txt">http://www.ietf.org/rfc/rfc2616.txt</a>

  * </pre></blockquote>

  *

  * Note about <code>fileNameMap</code>: In versions prior to JDK 1.1.6,

  * field <code>fileNameMap</code> of <code>URLConnection</code> was public.

  * In JDK 1.1.6 and later, <code>fileNameMap</code> is private; accessor

  * and mutator methods {@link #getFileNameMap() getFileNameMap} and

  * {@link #setFileNameMap(java.net.FileNameMap) setFileNameMap} are added

  * to access it.  This change is also described on the <a href=

  * "http://java.sun.com/products/jdk/1.2/compatibility.html">

  * Compatibility</a> page.

  *

  * Invoking the <tt>close()</tt> methods on the <tt>InputStream</tt> or <tt>OutputStream</tt> of an

  * <tt>URLConnection</tt> after a request may free network resources associated with this

  * instance, unless particular protocol specifications specify different behaviours

  * for it.

  *

  * @author  James Gosling

  * @see     java.net.URL#openConnection()

  * @see     java.net.URLConnection#connect()

  * @see     java.net.URLConnection#getContent()

  * @see     java.net.URLConnection#getContentEncoding()

  * @see     java.net.URLConnection#getContentLength()

  * @see     java.net.URLConnection#getContentType()

  * @see     java.net.URLConnection#getDate()

  * @see     java.net.URLConnection#getExpiration()

  * @see     java.net.URLConnection#getHeaderField(int)

  * @see     java.net.URLConnection#getHeaderField(java.lang.String)

  * @see     java.net.URLConnection#getInputStream()

  * @see     java.net.URLConnection#getLastModified()

  * @see     java.net.URLConnection#getOutputStream()

  * @see     java.net.URLConnection#setAllowUserInteraction(boolean)

  * @see     java.net.URLConnection#setDefaultUseCaches(boolean)

  * @see     java.net.URLConnection#setDoInput(boolean)

  * @see     java.net.URLConnection#setDoOutput(boolean)

  * @see     java.net.URLConnection#setIfModifiedSince(long)

  * @see     java.net.URLConnection#setRequestProperty(java.lang.String, java.lang.String)

  * @see     java.net.URLConnection#setUseCaches(boolean)

  * @since   JDK1.0

  */

 public abstract class URLConnection {

    /**

      * The URL represents the remote object on the World Wide Web to

      * which this connection is opened.

      * <p>

      * The value of this field can be accessed by the

      * <code>getURL</code> method.

      * <p>

      * The default value of this variable is the value of the URL

      * argument in the <code>URLConnection</code> constructor.

      *

      * @see     java.net.URLConnection#getURL()

      * @see     java.net.URLConnection#url

      */

     protected URL url;

    /**

      * This variable is set by the <code>setDoInput</code> method. Its

      * value is returned by the <code>getDoInput</code> method.

      * <p>

      * A URL connection can be used for input and/or output. Setting the

      * <code>doInput</code> flag to <code>true</code> indicates that

      * the application intends to read data from the URL connection.

      * <p>

      * The default value of this field is <code>true</code>.

      *

      * @see     java.net.URLConnection#getDoInput()

      * @see     java.net.URLConnection#setDoInput(boolean)

      */

     protected boolean doInput = true;

    /**

      * This variable is set by the <code>setDoOutput</code> method. Its

      * value is returned by the <code>getDoOutput</code> method.

      * <p>

      * A URL connection can be used for input and/or output. Setting the

      * <code>doOutput</code> flag to <code>true</code> indicates

      * that the application intends to write data to the URL connection.

      * <p>

      * The default value of this field is <code>false</code>.

      *

      * @see     java.net.URLConnection#getDoOutput()

      * @see     java.net.URLConnection#setDoOutput(boolean)

      */

     protected boolean doOutput = false;

     private static boolean defaultAllowUserInteraction = false;

    /**

      * If <code>true</code>, this <code>URL</code> is being examined in

      * a context in which it makes sense to allow user interactions such

      * as popping up an authentication dialog. If <code>false</code>,

      * then no user interaction is allowed.

      * <p>

      * The value of this field can be set by the

      * <code>setAllowUserInteraction</code> method.

      * Its value is returned by the

      * <code>getAllowUserInteraction</code> method.

      * Its default value is the value of the argument in the last invocation

      * of the <code>setDefaultAllowUserInteraction</code> method.

      *

      * @see     java.net.URLConnection#getAllowUserInteraction()

      * @see     java.net.URLConnection#setAllowUserInteraction(boolean)

      * @see     java.net.URLConnection#setDefaultAllowUserInteraction(boolean)

      */

     protected boolean allowUserInteraction = defaultAllowUserInteraction;

     private static boolean defaultUseCaches = true;

    /**

      * If <code>true</code>, the protocol is allowed to use caching

      * whenever it can. If <code>false</code>, the protocol must always

      * try to get a fresh copy of the object.

      * <p>

      * This field is set by the <code>setUseCaches</code> method. Its

      * value is returned by the <code>getUseCaches</code> method.

      * <p>

      * Its default value is the value given in the last invocation of the

      * <code>setDefaultUseCaches</code> method.

      *

      * @see     java.net.URLConnection#setUseCaches(boolean)

      * @see     java.net.URLConnection#getUseCaches()

      * @see     java.net.URLConnection#setDefaultUseCaches(boolean)

      */

     protected boolean useCaches = defaultUseCaches;

    /**

      * Some protocols support skipping the fetching of the object unless

      * the object has been modified more recently than a certain time.

      * <p>

      * A nonzero value gives a time as the number of milliseconds since

      * January 1, 1970, GMT. The object is fetched only if it has been

      * modified more recently than that time.

      * <p>

      * This variable is set by the <code>setIfModifiedSince</code>

      * method. Its value is returned by the

      * <code>getIfModifiedSince</code> method.

      * <p>

      * The default value of this field is <code>0</code>, indicating

      * that the fetching must always occur.

      *

      * @see     java.net.URLConnection#getIfModifiedSince()

      * @see     java.net.URLConnection#setIfModifiedSince(long)

      */

     protected long ifModifiedSince = 0;

    /**

      * If <code>false</code>, this connection object has not created a

      * communications link to the specified URL. If <code>true</code>,

      * the communications link has been established.

      */

     protected boolean connected = false;

     /**

      * @since 1.5

      */

     private int connectTimeout;

     private int readTimeout;

     /**

      * @since 1.6

      */

     private MessageHeader requests;

    /**

     * @since   JDK1.1

     */

     private static FileNameMap fileNameMap;

     /**

      * @since 1.2.2

      */

     private static boolean fileNameMapLoaded = false;

     /**

      * Loads filename map (a mimetable) from a data file. It will

      * first try to load the user-specific table, defined

      * by "content.types.user.table" property. If that fails,

      * it tries to load the default built-in table at

      * lib/content-types.properties under java home.

      *

      * @return the FileNameMap

      * @since 1.2

      * @see #setFileNameMap(java.net.FileNameMap)

      */

     public static synchronized FileNameMap getFileNameMap() {

         if ((fileNameMap == null) && !fileNameMapLoaded) {

             fileNameMap = sun.net.www.MimeTable.loadTable();

             fileNameMapLoaded = true;

         }

         return new FileNameMap() {

             private FileNameMap map = fileNameMap;

             public String getContentTypeFor(String fileName) {

                 return map.getContentTypeFor(fileName);

             }

         };

     }

     /**

      * Sets the FileNameMap.

      * <p>

      * If there is a security manager, this method first calls

      * the security manager's <code>checkSetFactory</code> method

      * to ensure the operation is allowed.

      * This could result in a SecurityException.

      *

      * @param map the FileNameMap to be set

      * @exception  SecurityException  if a security manager exists and its

      *             <code>checkSetFactory</code> method doesn't allow the operation.

      * @see        SecurityManager#checkSetFactory

      * @see #getFileNameMap()

      * @since 1.2

      */

     public static void setFileNameMap(FileNameMap map) {

         SecurityManager sm = System.getSecurityManager();

         if (sm != null) sm.checkSetFactory();

         fileNameMap = map;

     }

     /**

      * Opens a communications link to the resource referenced by this

      * URL, if such a connection has not already been established.

      * <p>

      * If the <code>connect</code> method is called when the connection

      * has already been opened (indicated by the <code>connected</code>

      * field having the value <code>true</code>), the call is ignored.

      * <p>

      * URLConnection objects go through two phases: first they are

      * created, then they are connected.  After being created, and

      * before being connected, various options can be specified

      * (e.g., doInput and UseCaches).  After connecting, it is an

      * error to try to set them.  Operations that depend on being

      * connected, like getContentLength, will implicitly perform the

      * connection, if necessary.

      *

      * @throws SocketTimeoutException if the timeout expires before

      *               the connection can be established

      * @exception  IOException  if an I/O error occurs while opening the

      *               connection.

      * @see java.net.URLConnection#connected

      * @see #getConnectTimeout()

      * @see #setConnectTimeout(int)

      */

     abstract public void connect() throws IOException;

     /**

      * Sets a specified timeout value, in milliseconds, to be used

      * when opening a communications link to the resource referenced

      * by this URLConnection.  If the timeout expires before the

      * connection can be established, a

      * java.net.SocketTimeoutException is raised. A timeout of zero is

      * interpreted as an infinite timeout.

      * <p> Some non-standard implmentation of this method may ignore

      * the specified timeout. To see the connect timeout set, please

      * call getConnectTimeout().

      *

      * @param timeout an <code>int</code> that specifies the connect

      *               timeout value in milliseconds

      * @throws IllegalArgumentException if the timeout parameter is negative

      *

      * @see #getConnectTimeout()

      * @see #connect()

      * @since 1.5

      */

     public void setConnectTimeout(int timeout) {

         if (timeout < 0) {

             throw new IllegalArgumentException("timeout can not be negative");

         }

         connectTimeout = timeout;

     }

     /**

      * Returns setting for connect timeout.

      * <p>

      * 0 return implies that the option is disabled

      * (i.e., timeout of infinity).

      *

      * @return an <code>int</code> that indicates the connect timeout

      *         value in milliseconds

      * @see #setConnectTimeout(int)

      * @see #connect()

      * @since 1.5

      */

     public int getConnectTimeout() {

         return connectTimeout;

     }

     /**

      * Sets the read timeout to a specified timeout, in

      * milliseconds. A non-zero value specifies the timeout when

      * reading from Input stream when a connection is established to a

      * resource. If the timeout expires before there is data available

      * for read, a java.net.SocketTimeoutException is raised. A

      * timeout of zero is interpreted as an infinite timeout.

      *

      *<p> Some non-standard implementation of this method ignores the

      * specified timeout. To see the read timeout set, please call

      * getReadTimeout().

      *

      * @param timeout an <code>int</code> that specifies the timeout

      * value to be used in milliseconds

      * @throws IllegalArgumentException if the timeout parameter is negative

      *

      * @see #getReadTimeout()

      * @see InputStream#read()

      * @since 1.5

      */

     public void setReadTimeout(int timeout) {

         if (timeout < 0) {

             throw new IllegalArgumentException("timeout can not be negative");

         }

         readTimeout = timeout;

     }

     /**

      * Returns setting for read timeout. 0 return implies that the

      * option is disabled (i.e., timeout of infinity).

      *

      * @return an <code>int</code> that indicates the read timeout

      *         value in milliseconds

      *

      * @see #setReadTimeout(int)

      * @see InputStream#read()

      * @since 1.5

      */

     public int getReadTimeout() {

         return readTimeout;

     }

     /**

      * Constructs a URL connection to the specified URL. A connection to

      * the object referenced by the URL is not created.

      *

      * @param   url   the specified URL.

      */

     protected URLConnection(URL url) {

         this.url = url;

     }

     /**

      * Returns the value of this <code>URLConnection</code>'s <code>URL</code>

      * field.

      *

      * @return  the value of this <code>URLConnection</code>'s <code>URL</code>

      *          field.

      * @see     java.net.URLConnection#url

      */

     public URL getURL() {

         return url;

     }

     /**

      * Returns the value of the <code>content-length</code> header field.

      * <P>

      * <B>Note</B>: {@link #getContentLengthLong() getContentLengthLong()}

      * should be preferred over this method, since it returns a {@code long}

      * instead and is therefore more portable.</P>

      *

      * @return  the content length of the resource that this connection's URL

      *          references, {@code -1} if the content length is not known,

      *          or if the content length is greater than Integer.MAX_VALUE.

      */

     public int getContentLength() {

         long l = getContentLengthLong();

         if (l > Integer.MAX_VALUE)

             return -1;

         return (int) l;

     }

     /**

      * Returns the value of the <code>content-length</code> header field as a

      * long.

      *

      * @return  the content length of the resource that this connection's URL

      *          references, or <code>-1</code> if the content length is

      *          not known.

      * @since 7.0

      */

     public long getContentLengthLong() {

         return getHeaderFieldLong("content-length", -1);

     }

     /**

      * Returns the value of the <code>content-type</code> header field.

      *

      * @return  the content type of the resource that the URL references,

      *          or <code>null</code> if not known.

      * @see     java.net.URLConnection#getHeaderField(java.lang.String)

      */

     public String getContentType() {

         return getHeaderField("content-type");

     }

     /**

      * Returns the value of the <code>content-encoding</code> header field.

      *

      * @return  the content encoding of the resource that the URL references,

      *          or <code>null</code> if not known.

      * @see     java.net.URLConnection#getHeaderField(java.lang.String)

      */

     public String getContentEncoding() {

         return getHeaderField("content-encoding");

     }

     /**

      * Returns the value of the <code>expires</code> header field.

      *

      * @return  the expiration date of the resource that this URL references,

      *          or 0 if not known. The value is the number of milliseconds since

      *          January 1, 1970 GMT.

      * @see     java.net.URLConnection#getHeaderField(java.lang.String)

      */

     public long getExpiration() {

         return getHeaderFieldDate("expires", 0);

     }

     /**

      * Returns the value of the <code>date</code> header field.

      *

      * @return  the sending date of the resource that the URL references,

      *          or <code>0</code> if not known. The value returned is the

      *          number of milliseconds since January 1, 1970 GMT.

      * @see     java.net.URLConnection#getHeaderField(java.lang.String)

      */

     public long getDate() {

         return getHeaderFieldDate("date", 0);

     }

     /**

      * Returns the value of the <code>last-modified</code> header field.

      * The result is the number of milliseconds since January 1, 1970 GMT.

      *

      * @return  the date the resource referenced by this

      *          <code>URLConnection</code> was last modified, or 0 if not known.

      * @see     java.net.URLConnection#getHeaderField(java.lang.String)

      */

     public long getLastModified() {

         return getHeaderFieldDate("last-modified", 0);

     }

     /**

      * Returns the value of the named header field.

      * <p>

      * If called on a connection that sets the same header multiple times

      * with possibly different values, only the last value is returned.

      *

      *

      * @param   name   the name of a header field.

      * @return  the value of the named header field, or <code>null</code>

      *          if there is no such field in the header.

      */

     public String getHeaderField(String name) {

         return null;

     }

     /**

      * Returns an unmodifiable Map of the header fields.

      * The Map keys are Strings that represent the

      * response-header field names. Each Map value is an

      * unmodifiable List of Strings that represents

      * the corresponding field values.

      *

      * @return a Map of header fields

      * @since 1.4

      */

     public Map<String,List<String>> getHeaderFields() {

         return Collections.EMPTY_MAP;

     }

     /**

      * Returns the value of the named field parsed as a number.

      * <p>

      * This form of <code>getHeaderField</code> exists because some

      * connection types (e.g., <code>http-ng</code>) have pre-parsed

      * headers. Classes for that connection type can override this method

      * and short-circuit the parsing.

      *

      * @param   name      the name of the header field.

      * @param   Default   the default value.

      * @return  the value of the named field, parsed as an integer. The

      *          <code>Default</code> value is returned if the field is

      *          missing or malformed.

      */

     public int getHeaderFieldInt(String name, int Default) {

         String value = getHeaderField(name);

         try {

             return Integer.parseInt(value);

         } catch (Exception e) { }

         return Default;

     }

     /**

      * Returns the value of the named field parsed as a number.

      * <p>

      * This form of <code>getHeaderField</code> exists because some

      * connection types (e.g., <code>http-ng</code>) have pre-parsed

      * headers. Classes for that connection type can override this method

      * and short-circuit the parsing.

      *

      * @param   name      the name of the header field.

      * @param   Default   the default value.

      * @return  the value of the named field, parsed as a long. The

      *          <code>Default</code> value is returned if the field is

      *          missing or malformed.

      * @since 7.0

      */

     public long getHeaderFieldLong(String name, long Default) {

         String value = getHeaderField(name);

         try {

             return Long.parseLong(value);

         } catch (Exception e) { }

         return Default;

     }

     /**

      * Returns the value of the named field parsed as date.

      * The result is the number of milliseconds since January 1, 1970 GMT

      * represented by the named field.

      * <p>

      * This form of <code>getHeaderField</code> exists because some

      * connection types (e.g., <code>http-ng</code>) have pre-parsed

      * headers. Classes for that connection type can override this method

      * and short-circuit the parsing.

      *

      * @param   name     the name of the header field.

      * @param   Default   a default value.

      * @return  the value of the field, parsed as a date. The value of the

      *          <code>Default</code> argument is returned if the field is

      *          missing or malformed.

      */

     public long getHeaderFieldDate(String name, long Default) {

         String value = getHeaderField(name);

         try {

             return Date.parse(value);

         } catch (Exception e) { }

         return Default;

     }

     /**

      * Returns the key for the <code>n</code><sup>th</sup> header field.

      * It returns <code>null</code> if there are fewer than <code>n+1</code> fields.

      *

      * @param   n   an index, where n>=0

      * @return  the key for the <code>n</code><sup>th</sup> header field,

      *          or <code>null</code> if there are fewer than <code>n+1</code>

      *          fields.

      */

     public String getHeaderFieldKey(int n) {

         return null;

     }

     /**

      * Returns the value for the <code>n</code><sup>th</sup> header field.

      * It returns <code>null</code> if there are fewer than

      * <code>n+1</code>fields.

      * <p>

      * This method can be used in conjunction with the

      * {@link #getHeaderFieldKey(int) getHeaderFieldKey} method to iterate through all

      * the headers in the message.

      *

      * @param   n   an index, where n>=0

      * @return  the value of the <code>n</code><sup>th</sup> header field

      *          or <code>null</code> if there are fewer than <code>n+1</code> fields

      * @see     java.net.URLConnection#getHeaderFieldKey(int)

      */

     public String getHeaderField(int n) {

         return null;

     }

     /**

      * Retrieves the contents of this URL connection.

      * <p>

      * This method first determines the content type of the object by

      * calling the <code>getContentType</code> method. If this is

      * the first time that the application has seen that specific content

      * type, a content handler for that content type is created:

      * <ol>

      * <li>If the application has set up a content handler factory instance

      *     using the <code>setContentHandlerFactory</code> method, the

      *     <code>createContentHandler</code> method of that instance is called

      *     with the content type as an argument; the result is a content

      *     handler for that content type.

      * <li>If no content handler factory has yet been set up, or if the

      *     factory's <code>createContentHandler</code> method returns

      *     <code>null</code>, then the application loads the class named:

      *     <blockquote><pre>

      *         sun.net.www.content.&lt;<i>contentType</i>&gt;

      *     </pre></blockquote>

      *     where &lt;<i>contentType</i>&gt; is formed by taking the

      *     content-type string, replacing all slash characters with a

      *     <code>period</code> ('.'), and all other non-alphanumeric characters

      *     with the underscore character '<code>_</code>'. The alphanumeric

      *     characters are specifically the 26 uppercase ASCII letters

      *     '<code>A</code>' through '<code>Z</code>', the 26 lowercase ASCII

      *     letters '<code>a</code>' through '<code>z</code>', and the 10 ASCII

      *     digits '<code>0</code>' through '<code>9</code>'. If the specified

      *     class does not exist, or is not a subclass of

      *     <code>ContentHandler</code>, then an

      *     <code>UnknownServiceException</code> is thrown.

      * </ol>

      *

      * @return     the object fetched. The <code>instanceof</code> operator

      *               should be used to determine the specific kind of object

      *               returned.

      * @exception  IOException              if an I/O error occurs while

      *               getting the content.

      * @exception  UnknownServiceException  if the protocol does not support

      *               the content type.

      * @see        java.net.ContentHandlerFactory#createContentHandler(java.lang.String)

      * @see        java.net.URLConnection#getContentType()

      * @see        java.net.URLConnection#setContentHandlerFactory(java.net.ContentHandlerFactory)

      */

     public Object getContent() throws IOException {

         // Must call getInputStream before GetHeaderField gets called

         // so that FileNotFoundException has a chance to be thrown up

         // from here without being caught.

         getInputStream();

         return getContentHandler().getContent(this);

     }

     /**

      * Retrieves the contents of this URL connection.

      *

      * @param classes the <code>Class</code> array

      * indicating the requested types

      * @return     the object fetched that is the first match of the type

      *               specified in the classes array. null if none of

      *               the requested types are supported.

      *               The <code>instanceof</code> operator should be used to

      *               determine the specific kind of object returned.

      * @exception  IOException              if an I/O error occurs while

      *               getting the content.

      * @exception  UnknownServiceException  if the protocol does not support

      *               the content type.

      * @see        java.net.URLConnection#getContent()

      * @see        java.net.ContentHandlerFactory#createContentHandler(java.lang.String)

      * @see        java.net.URLConnection#getContent(java.lang.Class[])

      * @see        java.net.URLConnection#setContentHandlerFactory(java.net.ContentHandlerFactory)

      * @since 1.3

      */

     public Object getContent(Class[] classes) throws IOException {

         // Must call getInputStream before GetHeaderField gets called

         // so that FileNotFoundException has a chance to be thrown up

         // from here without being caught.

         getInputStream();

         return getContentHandler().getContent(this, classes);

     }

     /**

      * Returns a permission object representing the permission

      * necessary to make the connection represented by this

      * object. This method returns null if no permission is

      * required to make the connection. By default, this method

      * returns <code>java.security.AllPermission</code>. Subclasses

      * should override this method and return the permission

      * that best represents the permission required to make a

      * a connection to the URL. For example, a <code>URLConnection</code>

      * representing a <code>file:</code> URL would return a

      * <code>java.io.FilePermission</code> object.

      *

      * <p>The permission returned may dependent upon the state of the

      * connection. For example, the permission before connecting may be

      * different from that after connecting. For example, an HTTP

      * sever, say foo.com, may redirect the connection to a different

      * host, say bar.com. Before connecting the permission returned by

      * the connection will represent the permission needed to connect

      * to foo.com, while the permission returned after connecting will

      * be to bar.com.

      *

      * <p>Permissions are generally used for two purposes: to protect

      * caches of objects obtained through URLConnections, and to check

      * the right of a recipient to learn about a particular URL. In

      * the first case, the permission should be obtained

      * <em>after</em> the object has been obtained. For example, in an

      * HTTP connection, this will represent the permission to connect

      * to the host from which the data was ultimately fetched. In the

      * second case, the permission should be obtained and tested

      * <em>before</em> connecting.

      *

      * @return the permission object representing the permission

      * necessary to make the connection represented by this

      * URLConnection.

      *

      * @exception IOException if the computation of the permission

      * requires network or file I/O and an exception occurs while

      * computing it.

      */

     public Permission getPermission() throws IOException {

         return SecurityConstants.ALL_PERMISSION;

     }

     /**

      * Returns an input stream that reads from this open connection.

      *

      * A SocketTimeoutException can be thrown when reading from the

      * returned input stream if the read timeout expires before data

      * is available for read.

      *

      * @return     an input stream that reads from this open connection.

      * @exception  IOException              if an I/O error occurs while

      *               creating the input stream.

      * @exception  UnknownServiceException  if the protocol does not support

      *               input.

      * @see #setReadTimeout(int)

      * @see #getReadTimeout()

      */

     public InputStream getInputStream() throws IOException {

         throw new UnknownServiceException("protocol doesn't support input");

     }

     /**

      * Returns an output stream that writes to this connection.

      *

      * @return     an output stream that writes to this connection.

      * @exception  IOException              if an I/O error occurs while

      *               creating the output stream.

      * @exception  UnknownServiceException  if the protocol does not support

      *               output.

      */

     public OutputStream getOutputStream() throws IOException {

         throw new UnknownServiceException("protocol doesn't support output");

     }

     /**

      * Returns a <code>String</code> representation of this URL connection.

      *

      * @return  a string representation of this <code>URLConnection</code>.

      */

     public String toString() {

         return this.getClass().getName() + ":" + url;

     }

     /**

      * Sets the value of the <code>doInput</code> field for this

      * <code>URLConnection</code> to the specified value.

      * <p>

      * A URL connection can be used for input and/or output.  Set the DoInput

      * flag to true if you intend to use the URL connection for input,

      * false if not.  The default is true.

      *

      * @param   doinput   the new value.

      * @throws IllegalStateException if already connected

      * @see     java.net.URLConnection#doInput

      * @see #getDoInput()

      */

     public void setDoInput(boolean doinput) {

         if (connected)

             throw new IllegalStateException("Already connected");

         doInput = doinput;

     }

     /**

      * Returns the value of this <code>URLConnection</code>'s

      * <code>doInput</code> flag.

      *

      * @return  the value of this <code>URLConnection</code>'s

      *          <code>doInput</code> flag.

      * @see     #setDoInput(boolean)

      */

     public boolean getDoInput() {

         return doInput;

     }

     /**

      * Sets the value of the <code>doOutput</code> field for this

      * <code>URLConnection</code> to the specified value.

      * <p>

      * A URL connection can be used for input and/or output.  Set the DoOutput

      * flag to true if you intend to use the URL connection for output,

      * false if not.  The default is false.

      *

      * @param   dooutput   the new value.

      * @throws IllegalStateException if already connected

      * @see #getDoOutput()

      */

     public void setDoOutput(boolean dooutput) {

         if (connected)

             throw new IllegalStateException("Already connected");

         doOutput = dooutput;

     }

     /**

      * Returns the value of this <code>URLConnection</code>'s

      * <code>doOutput</code> flag.

      *

      * @return  the value of this <code>URLConnection</code>'s

      *          <code>doOutput</code> flag.

      * @see     #setDoOutput(boolean)

      */

     public boolean getDoOutput() {

         return doOutput;

     }

     /**

      * Set the value of the <code>allowUserInteraction</code> field of

      * this <code>URLConnection</code>.

      *

      * @param   allowuserinteraction   the new value.

      * @throws IllegalStateException if already connected

      * @see     #getAllowUserInteraction()

      */

     public void setAllowUserInteraction(boolean allowuserinteraction) {

         if (connected)

             throw new IllegalStateException("Already connected");

         allowUserInteraction = allowuserinteraction;

     }

     /**

      * Returns the value of the <code>allowUserInteraction</code> field for

      * this object.

      *

      * @return  the value of the <code>allowUserInteraction</code> field for

      *          this object.

      * @see     #setAllowUserInteraction(boolean)

      */

     public boolean getAllowUserInteraction() {

         return allowUserInteraction;

     }

     /**

      * Sets the default value of the

      * <code>allowUserInteraction</code> field for all future

      * <code>URLConnection</code> objects to the specified value.

      *

      * @param   defaultallowuserinteraction   the new value.

      * @see     #getDefaultAllowUserInteraction()

      */

     public static void setDefaultAllowUserInteraction(boolean defaultallowuserinteraction) {

         defaultAllowUserInteraction = defaultallowuserinteraction;

     }

     /**

      * Returns the default value of the <code>allowUserInteraction</code>

      * field.

      * <p>

      * Ths default is "sticky", being a part of the static state of all

      * URLConnections.  This flag applies to the next, and all following

      * URLConnections that are created.

      *

      * @return  the default value of the <code>allowUserInteraction</code>

      *          field.

      * @see     #setDefaultAllowUserInteraction(boolean)

      */

     public static boolean getDefaultAllowUserInteraction() {

         return defaultAllowUserInteraction;

     }

     /**

      * Sets the value of the <code>useCaches</code> field of this

      * <code>URLConnection</code> to the specified value.

      * <p>

      * Some protocols do caching of documents.  Occasionally, it is important

      * to be able to "tunnel through" and ignore the caches (e.g., the

      * "reload" button in a browser).  If the UseCaches flag on a connection

      * is true, the connection is allowed to use whatever caches it can.

      *  If false, caches are to be ignored.

      *  The default value comes from DefaultUseCaches, which defaults to

      * true.

      *

      * @param usecaches a <code>boolean</code> indicating whether

      * or not to allow caching

      * @throws IllegalStateException if already connected

      * @see #getUseCaches()

      */

     public void setUseCaches(boolean usecaches) {

         if (connected)

             throw new IllegalStateException("Already connected");

         useCaches = usecaches;

     }

     /**

      * Returns the value of this <code>URLConnection</code>'s

      * <code>useCaches</code> field.

      *

      * @return  the value of this <code>URLConnection</code>'s

      *          <code>useCaches</code> field.

      * @see #setUseCaches(boolean)

      */

     public boolean getUseCaches() {

         return useCaches;

     }

     /**

      * Sets the value of the <code>ifModifiedSince</code> field of

      * this <code>URLConnection</code> to the specified value.

      *

      * @param   ifmodifiedsince   the new value.

      * @throws IllegalStateException if already connected

      * @see     #getIfModifiedSince()

      */

     public void setIfModifiedSince(long ifmodifiedsince) {

         if (connected)

             throw new IllegalStateException("Already connected");

         ifModifiedSince = ifmodifiedsince;

     }

     /**

      * Returns the value of this object's <code>ifModifiedSince</code> field.

      *

      * @return  the value of this object's <code>ifModifiedSince</code> field.

      * @see #setIfModifiedSince(long)

      */

     public long getIfModifiedSince() {

         return ifModifiedSince;

     }

    /**

      * Returns the default value of a <code>URLConnection</code>'s

      * <code>useCaches</code> flag.

      * <p>

      * Ths default is "sticky", being a part of the static state of all

      * URLConnections.  This flag applies to the next, and all following

      * URLConnections that are created.

      *

      * @return  the default value of a <code>URLConnection</code>'s

      *          <code>useCaches</code> flag.

      * @see     #setDefaultUseCaches(boolean)

      */

     public boolean getDefaultUseCaches() {

         return defaultUseCaches;

     }

    /**

      * Sets the default value of the <code>useCaches</code> field to the

      * specified value.

      *

      * @param   defaultusecaches   the new value.

      * @see     #getDefaultUseCaches()

      */

     public void setDefaultUseCaches(boolean defaultusecaches) {

         defaultUseCaches = defaultusecaches;

     }

     /**

      * Sets the general request property. If a property with the key already

      * exists, overwrite its value with the new value.

      *

      * <p> NOTE: HTTP requires all request properties which can

      * legally have multiple instances with the same key

      * to use a comma-seperated list syntax which enables multiple

      * properties to be appended into a single property.

      *

      * @param   key     the keyword by which the request is known

      *                  (e.g., "<code>Accept</code>").

      * @param   value   the value associated with it.

      * @throws IllegalStateException if already connected

      * @throws NullPointerException if key is <CODE>null</CODE>

      * @see #getRequestProperty(java.lang.String)

      */

     public void setRequestProperty(String key, String value) {

         if (connected)

             throw new IllegalStateException("Already connected");

         if (key == null)

             throw new NullPointerException ("key is null");

         if (requests == null)

             requests = new MessageHeader();

         requests.set(key, value);

     }

     /**

      * Adds a general request property specified by a

      * key-value pair.  This method will not overwrite

      * existing values associated with the same key.

      *

      * @param   key     the keyword by which the request is known

      *                  (e.g., "<code>Accept</code>").

      * @param   value  the value associated with it.

      * @throws IllegalStateException if already connected

      * @throws NullPointerException if key is null

      * @see #getRequestProperties()

      * @since 1.4

      */

     public void addRequestProperty(String key, String value) {

         if (connected)

             throw new IllegalStateException("Already connected");

         if (key == null)

             throw new NullPointerException ("key is null");

         if (requests == null)

             requests = new MessageHeader();

         requests.add(key, value);

     }

     /**

      * Returns the value of the named general request property for this

      * connection.

      *

      * @param key the keyword by which the request is known (e.g., "Accept").

      * @return  the value of the named general request property for this

      *           connection. If key is null, then null is returned.

      * @throws IllegalStateException if already connected

      * @see #setRequestProperty(java.lang.String, java.lang.String)

      */

     public String getRequestProperty(String key) {

         if (connected)

             throw new IllegalStateException("Already connected");

         if (requests == null)

             return null;

         return requests.findValue(key);

     }

     /**

      * Returns an unmodifiable Map of general request

      * properties for this connection. The Map keys

      * are Strings that represent the request-header

      * field names. Each Map value is a unmodifiable List

      * of Strings that represents the corresponding

      * field values.

      *

      * @return  a Map of the general request properties for this connection.

      * @throws IllegalStateException if already connected

      * @since 1.4

      */

     public Map<String,List<String>> getRequestProperties() {

         if (connected)

             throw new IllegalStateException("Already connected");

         if (requests == null)

             return Collections.EMPTY_MAP;

         return requests.getHeaders(null);

     }

     /**

      * Sets the default value of a general request property. When a

      * <code>URLConnection</code> is created, it is initialized with

      * these properties.

      *

      * @param   key     the keyword by which the request is known

      *                  (e.g., "<code>Accept</code>").

      * @param   value   the value associated with the key.

      *

      * @see java.net.URLConnection#setRequestProperty(java.lang.String,java.lang.String)

      *

      * @deprecated The instance specific setRequestProperty method

      * should be used after an appropriate instance of URLConnection

      * is obtained. Invoking this method will have no effect.

      *

      * @see #getDefaultRequestProperty(java.lang.String)

      */

     @Deprecated

     public static void setDefaultRequestProperty(String key, String value) {

     }

     /**

      * Returns the value of the default request property. Default request

      * properties are set for every connection.

      *

      * @param key the keyword by which the request is known (e.g., "Accept").

      * @return  the value of the default request property

      * for the specified key.

      *

      * @see java.net.URLConnection#getRequestProperty(java.lang.String)

      *

      * @deprecated The instance specific getRequestProperty method

      * should be used after an appropriate instance of URLConnection

      * is obtained.

      *

      * @see #setDefaultRequestProperty(java.lang.String, java.lang.String)

      */

     @Deprecated

     public static String getDefaultRequestProperty(String key) {

         return null;

     }

     /**

      * The ContentHandler factory.

      */

     static ContentHandlerFactory factory;

     /**

      * Sets the <code>ContentHandlerFactory</code> of an

      * application. It can be called at most once by an application.

      * <p>

      * The <code>ContentHandlerFactory</code> instance is used to

      * construct a content handler from a content type

      * <p>

      * If there is a security manager, this method first calls

      * the security manager's <code>checkSetFactory</code> method

      * to ensure the operation is allowed.

      * This could result in a SecurityException.

      *

      * @param      fac   the desired factory.

      * @exception  Error  if the factory has already been defined.

      * @exception  SecurityException  if a security manager exists and its

      *             <code>checkSetFactory</code> method doesn't allow the operation.

      * @see        java.net.ContentHandlerFactory

      * @see        java.net.URLConnection#getContent()

      * @see        SecurityManager#checkSetFactory

      */

     public static synchronized void setContentHandlerFactory(ContentHandlerFactory fac) {

         if (factory != null) {

             throw new Error("factory already defined");

         }

         SecurityManager security = System.getSecurityManager();

         if (security != null) {

             security.checkSetFactory();

         }

         factory = fac;

     }

     private static Hashtable handlers = new Hashtable();

     /**

      * Gets the Content Handler appropriate for this connection.

      * @param connection the connection to use.

      */

     synchronized ContentHandler getContentHandler()

     throws UnknownServiceException

     {

         String contentType = stripOffParameters(getContentType());

         ContentHandler handler = null;

         if (contentType == null)

             throw new UnknownServiceException("no content-type");

         try {

             handler = (ContentHandler) handlers.get(contentType);

             if (handler != null)

                 return handler;

         } catch(Exception e) {

         }

         if (factory != null)

             handler = factory.createContentHandler(contentType);

         if (handler == null) {

             try {

                 handler = lookupContentHandlerClassFor(contentType);

             } catch(Exception e) {

                 e.printStackTrace();

                 handler = UnknownContentHandler.INSTANCE;

             }

             handlers.put(contentType, handler);

         }

         return handler;

     }

     /*

      * Media types are in the format: type/subtype*(; parameter).

      * For looking up the content handler, we should ignore those

      * parameters.

      */

     private String stripOffParameters(String contentType)

     {

         if (contentType == null)

             return null;

         int index = contentType.indexOf(';');

         if (index > 0)

             return contentType.substring(0, index);

         else

             return contentType;

     }

     private static final String contentClassPrefix = "sun.net.www.content";

     private static final String contentPathProp = "java.content.handler.pkgs";

     /**

      * Looks for a content handler in a user-defineable set of places.

      * By default it looks in sun.net.www.content, but users can define a

      * vertical-bar delimited set of class prefixes to search through in

      * addition by defining the java.content.handler.pkgs property.

      * The class name must be of the form:

      * <pre>

      *     {package-prefix}.{major}.{minor}

      * e.g.

      *     YoyoDyne.experimental.text.plain

      * </pre>

      */

     private ContentHandler lookupContentHandlerClassFor(String contentType)

         throws InstantiationException, IllegalAccessException, ClassNotFoundException {

         String contentHandlerClassName = typeToPackageName(contentType);

         String contentHandlerPkgPrefixes =getContentHandlerPkgPrefixes();

         StringTokenizer packagePrefixIter =

             new StringTokenizer(contentHandlerPkgPrefixes, "|");

         while (packagePrefixIter.hasMoreTokens()) {

             String packagePrefix = packagePrefixIter.nextToken().trim();

             try {

                 String clsName = packagePrefix + "." + contentHandlerClassName;

                 Class cls = null;

                 try {

                     cls = Class.forName(clsName);

                 } catch (ClassNotFoundException e) {

                     ClassLoader cl = ClassLoader.getSystemClassLoader();

                     if (cl != null) {

                         cls = cl.loadClass(clsName);

                     }

                 }

                 if (cls != null) {

                     ContentHandler handler =

                         (ContentHandler)cls.newInstance();

                     return handler;

                 }

             } catch(Exception e) {

             }

         }

         return UnknownContentHandler.INSTANCE;

     }

     /**

      * Utility function to map a MIME content type into an equivalent

      * pair of class name components.  For example: "text/html" would

      * be returned as "text.html"

      */

     private String typeToPackageName(String contentType) {

         // make sure we canonicalize the class name: all lower case

         contentType = contentType.toLowerCase();

         int len = contentType.length();

         char nm[] = new char[len];

         contentType.getChars(0, len, nm, 0);

         for (int i = 0; i < len; i++) {

             char c = nm[i];

             if (c == '/') {

                 nm[i] = '.';

             } else if (!('A' <= c && c <= 'Z' ||

                        'a' <= c && c <= 'z' ||

                        '0' <= c && c <= '9')) {

                 nm[i] = '_';

             }

         }

         return new String(nm);

     }

     /**

      * Returns a vertical bar separated list of package prefixes for potential

      * content handlers.  Tries to get the java.content.handler.pkgs property

      * to use as a set of package prefixes to search.  Whether or not

      * that property has been defined, the sun.net.www.content is always

      * the last one on the returned package list.

      */

     private String getContentHandlerPkgPrefixes() {

         String packagePrefixList = AccessController.doPrivileged(

             new sun.security.action.GetPropertyAction(contentPathProp, ""));

         if (packagePrefixList != "") {

             packagePrefixList += "|";

         }

         return packagePrefixList + contentClassPrefix;

     }

     /**

      * Tries to determine the content type of an object, based

      * on the specified "file" component of a URL.

      * This is a convenience method that can be used by

      * subclasses that override the <code>getContentType</code> method.

      *

      * @param   fname   a filename.

      * @return  a guess as to what the content type of the object is,

      *          based upon its file name.

      * @see     java.net.URLConnection#getContentType()

      */

     public static String guessContentTypeFromName(String fname) {

         return getFileNameMap().getContentTypeFor(fname);

     }

     /**

      * Tries to determine the type of an input stream based on the

      * characters at the beginning of the input stream. This method can

      * be used by subclasses that override the

      * <code>getContentType</code> method.

      * <p>

      * Ideally, this routine would not be needed. But many

      * <code>http</code> servers return the incorrect content type; in

      * addition, there are many nonstandard extensions. Direct inspection

      * of the bytes to determine the content type is often more accurate

      * than believing the content type claimed by the <code>http</code> server.

      *

      * @param      is   an input stream that supports marks.

      * @return     a guess at the content type, or <code>null</code> if none

      *             can be determined.

      * @exception  IOException  if an I/O error occurs while reading the

      *               input stream.

      * @see        java.io.InputStream#mark(int)

      * @see        java.io.InputStream#markSupported()

      * @see        java.net.URLConnection#getContentType()

      */

     static public String guessContentTypeFromStream(InputStream is)

                         throws IOException {

         // If we can't read ahead safely, just give up on guessing

         if (!is.markSupported())

             return null;

         is.mark(16);

         int c1 = is.read();

         int c2 = is.read();

         int c3 = is.read();

         int c4 = is.read();

         int c5 = is.read();

         int c6 = is.read();

         int c7 = is.read();

         int c8 = is.read();

         int c9 = is.read();

         int c10 = is.read();

         int c11 = is.read();

         int c12 = is.read();

         int c13 = is.read();

         int c14 = is.read();

         int c15 = is.read();

         int c16 = is.read();

         is.reset();

         if (c1 == 0xCA && c2 == 0xFE && c3 == 0xBA && c4 == 0xBE) {

             return "application/java-vm";

         }

         if (c1 == 0xAC && c2 == 0xED) {

             // next two bytes are version number, currently 0x00 0x05

             return "application/x-java-serialized-object";

         }

         if (c1 == '<') {

             if (c2 == '!'

                 || ((c2 == 'h' && (c3 == 't' && c4 == 'm' && c5 == 'l' ||

                                    c3 == 'e' && c4 == 'a' && c5 == 'd') ||

                 (c2 == 'b' && c3 == 'o' && c4 == 'd' && c5 == 'y'))) ||

                 ((c2 == 'H' && (c3 == 'T' && c4 == 'M' && c5 == 'L' ||

                                 c3 == 'E' && c4 == 'A' && c5 == 'D') ||

                 (c2 == 'B' && c3 == 'O' && c4 == 'D' && c5 == 'Y')))) {

                 return "text/html";

             }

             if (c2 == '?' && c3 == 'x' && c4 == 'm' && c5 == 'l' && c6 == ' ') {

                 return "application/xml";

             }

         }

         // big and little (identical) endian UTF-8 encodings, with BOM

         if (c1 == 0xef &&  c2 == 0xbb &&  c3 == 0xbf) {

             if (c4 == '<' &&  c5 == '?' &&  c6 == 'x') {

                 return "application/xml";

             }

         }

         // big and little endian UTF-16 encodings, with byte order mark

         if (c1 == 0xfe && c2 == 0xff) {

             if (c3 == 0 && c4 == '<' && c5 == 0 && c6 == '?' &&

                 c7 == 0 && c8 == 'x') {

                 return "application/xml";

             }

         }

         if (c1 == 0xff && c2 == 0xfe) {

             if (c3 == '<' && c4 == 0 && c5 == '?' && c6 == 0 &&

                 c7 == 'x' && c8 == 0) {

                 return "application/xml";

             }

         }

         // big and little endian UTF-32 encodings, with BOM

         if (c1 == 0x00 &&  c2 == 0x00 &&  c3 == 0xfe &&  c4 == 0xff) {

             if (c5  == 0 && c6  == 0 && c7  == 0 && c8  == '<' &&

                 c9  == 0 && c10 == 0 && c11 == 0 && c12 == '?' &&

                 c13 == 0 && c14 == 0 && c15 == 0 && c16 == 'x') {

                 return "application/xml";

             }

         }

         if (c1 == 0xff &&  c2 == 0xfe &&  c3 == 0x00 &&  c4 == 0x00) {

             if (c5  == '<' && c6  == 0 && c7  == 0 && c8  == 0 &&

                 c9  == '?' && c10 == 0 && c11 == 0 && c12 == 0 &&

                 c13 == 'x' && c14 == 0 && c15 == 0 && c16 == 0) {

                 return "application/xml";

             }

         }

         if (c1 == 'G' && c2 == 'I' && c3 == 'F' && c4 == '8') {

             return "image/gif";

         }

         if (c1 == '#' && c2 == 'd' && c3 == 'e' && c4 == 'f') {

             return "image/x-bitmap";

         }

         if (c1 == '!' && c2 == ' ' && c3 == 'X' && c4 == 'P' &&

                         c5 == 'M' && c6 == '2') {

             return "image/x-pixmap";

         }

         if (c1 == 137 && c2 == 80 && c3 == 78 &&

                 c4 == 71 && c5 == 13 && c6 == 10 &&

                 c7 == 26 && c8 == 10) {

             return "image/png";

         }

         if (c1 == 0xFF && c2 == 0xD8 && c3 == 0xFF) {

             if (c4 == 0xE0) {

                 return "image/jpeg";

             }

             /**

              * File format used by digital cameras to store images.

              * Exif Format can be read by any application supporting

              * JPEG. Exif Spec can be found at:

              * http://www.pima.net/standards/it10/PIMA15740/Exif_2-1.PDF

              */

             if ((c4 == 0xE1) &&

                 (c7 == 'E' && c8 == 'x' && c9 == 'i' && c10 =='f' &&

                  c11 == 0)) {

                 return "image/jpeg";

             }

             if (c4 == 0xEE) {

                 return "image/jpg";

             }

         }

         if (c1 == 0xD0 && c2 == 0xCF && c3 == 0x11 && c4 == 0xE0 &&

             c5 == 0xA1 && c6 == 0xB1 && c7 == 0x1A && c8 == 0xE1) {

             /* Above is signature of Microsoft Structured Storage.

              * Below this, could have tests for various SS entities.

              * For now, just test for FlashPix.

              */

             if (checkfpx(is)) {

                 return "image/vnd.fpx";

             }

         }

         if (c1 == 0x2E && c2 == 0x73 && c3 == 0x6E && c4 == 0x64) {

             return "audio/basic";  // .au format, big endian

         }

         if (c1 == 0x64 && c2 == 0x6E && c3 == 0x73 && c4 == 0x2E) {

             return "audio/basic";  // .au format, little endian

         }

         if (c1 == 'R' && c2 == 'I' && c3 == 'F' && c4 == 'F') {

             /* I don't know if this is official but evidence

              * suggests that .wav files start with "RIFF" - brown

              */

             return "audio/x-wav";

         }

         return null;

     }

     /**

      * Check for FlashPix image data in InputStream is.  Return true if

      * the stream has FlashPix data, false otherwise.  Before calling this

      * method, the stream should have already been checked to be sure it

      * contains Microsoft Structured Storage data.

      */

     static private boolean checkfpx(InputStream is) throws IOException {

         /* Test for FlashPix image data in Microsoft Structured Storage format.

          * In general, should do this with calls to an SS implementation.

          * Lacking that, need to dig via offsets to get to the FlashPix

          * ClassID.  Details:

          *

          * Offset to Fpx ClsID from beginning of stream should be:

          *

          * FpxClsidOffset = rootEntryOffset + clsidOffset

          *

          * where: clsidOffset = 0x50.

          *        rootEntryOffset = headerSize + sectorSize*sectDirStart

          *                          + 128*rootEntryDirectory

          *

          *        where:  headerSize = 0x200 (always)

          *                sectorSize = 2 raised to power of uSectorShift,

          *                             which is found in the header at

          *                             offset 0x1E.

          *                sectDirStart = found in the header at offset 0x30.

          *                rootEntryDirectory = in general, should search for

          *                                     directory labelled as root.

          *                                     We will assume value of 0 (i.e.,

          *                                     rootEntry is in first directory)

          */

         // Mark the stream so we can reset it. 0x100 is enough for the first

         // few reads, but the mark will have to be reset and set again once

         // the offset to the root directory entry is computed. That offset

         // can be very large and isn't know until the stream has been read from

         is.mark(0x100);

         // Get the byte ordering located at 0x1E. 0xFE is Intel,

         // 0xFF is other

         long toSkip = (long)0x1C;

         long posn;

         if ((posn = skipForward(is, toSkip)) < toSkip) {

           is.reset();

           return false;

         }

         int c[] = new int[16];

         if (readBytes(c, 2, is) < 0) {

             is.reset();

             return false;

         }

         int byteOrder = c[0];

         posn+=2;

         int uSectorShift;

         if (readBytes(c, 2, is) < 0) {

             is.reset();

             return false;

         }

         if(byteOrder == 0xFE) {

             uSectorShift = c[0];

             uSectorShift += c[1] << 8;

         }

         else {

             uSectorShift = c[0] << 8;

             uSectorShift += c[1];

         }

         posn += 2;

         toSkip = (long)0x30 - posn;

         long skipped = 0;

         if ((skipped = skipForward(is, toSkip)) < toSkip) {

           is.reset();

           return false;

         }

         posn += skipped;

         if (readBytes(c, 4, is) < 0) {

             is.reset();

             return false;

         }

         int sectDirStart;

         if(byteOrder == 0xFE) {

             sectDirStart = c[0];

             sectDirStart += c[1] << 8;

             sectDirStart += c[2] << 16;

             sectDirStart += c[3] << 24;

         } else {

             sectDirStart =  c[0] << 24;

             sectDirStart += c[1] << 16;

             sectDirStart += c[2] << 8;

             sectDirStart += c[3];

         }

         posn += 4;

         is.reset(); // Reset back to the beginning

         toSkip = 0x200L + (long)(1<<uSectorShift)*sectDirStart + 0x50L;

         // Sanity check!

         if (toSkip < 0) {

             return false;

         }

         /*

          * How far can we skip? Is there any performance problem here?

          * This skip can be fairly long, at least 0x4c650 in at least

          * one case. Have to assume that the skip will fit in an int.

          * Leave room to read whole root dir

          */

         is.mark((int)toSkip+0x30);

         if ((skipForward(is, toSkip)) < toSkip) {

             is.reset();

             return false;

         }

         /* should be at beginning of ClassID, which is as follows

          * (in Intel byte order):

          *    00 67 61 56 54 C1 CE 11 85 53 00 AA 00 A1 F9 5B

          *

          * This is stored from Windows as long,short,short,char[8]

          * so for byte order changes, the order only changes for

          * the first 8 bytes in the ClassID.

          *

          * Test against this, ignoring second byte (Intel) since

          * this could change depending on part of Fpx file we have.

          */

         if (readBytes(c, 16, is) < 0) {

             is.reset();

             return false;

         }

         // intel byte order

         if (byteOrder == 0xFE &&

             c[0] == 0x00 && c[2] == 0x61 && c[3] == 0x56 &&

             c[4] == 0x54 && c[5] == 0xC1 && c[6] == 0xCE &&

             c[7] == 0x11 && c[8] == 0x85 && c[9] == 0x53 &&

             c[10]== 0x00 && c[11]== 0xAA && c[12]== 0x00 &&

             c[13]== 0xA1 && c[14]== 0xF9 && c[15]== 0x5B) {

             is.reset();

             return true;

         }

         // non-intel byte order

         else if (c[3] == 0x00 && c[1] == 0x61 && c[0] == 0x56 &&

             c[5] == 0x54 && c[4] == 0xC1 && c[7] == 0xCE &&

             c[6] == 0x11 && c[8] == 0x85 && c[9] == 0x53 &&

             c[10]== 0x00 && c[11]== 0xAA && c[12]== 0x00 &&

             c[13]== 0xA1 && c[14]== 0xF9 && c[15]== 0x5B) {

             is.reset();

             return true;

         }

         is.reset();

         return false;

     }

     /**

      * Tries to read the specified number of bytes from the stream

      * Returns -1, If EOF is reached before len bytes are read, returns 0

      * otherwise

      */

     static private int readBytes(int c[], int len, InputStream is)

                 throws IOException {

         byte buf[] = new byte[len];

         if (is.read(buf, 0, len) < len) {

             return -1;

         }

         // fill the passed in int array

         for (int i = 0; i < len; i++) {

              c[i] = buf[i] & 0xff;

         }

         return 0;

     }

     /**

      * Skips through the specified number of bytes from the stream

      * until either EOF is reached, or the specified

      * number of bytes have been skipped

      */

     static private long skipForward(InputStream is, long toSkip)

                 throws IOException {

         long eachSkip = 0;

         long skipped = 0;

         while (skipped != toSkip) {

             eachSkip = is.skip(toSkip - skipped);

             // check if EOF is reached

             if (eachSkip <= 0) {

                 if (is.read() == -1) {

                     return skipped ;

                 } else {

                     skipped++;

                 }

             }

             skipped += eachSkip;

         }

         return skipped;

     }

 }

 class UnknownContentHandler extends ContentHandler {

     static final ContentHandler INSTANCE = new UnknownContentHandler();

     public Object getContent(URLConnection uc) throws IOException {

         return uc.getInputStream();

     }

 }