URLStreamHandler is the common
- * superclass for all stream protocol handlers. A stream protocol
- * handler knows how to make a connection for a particular protocol
- * type, such as http, ftp, or
- * gopher.
- *
- * In most cases, an instance of a URLStreamHandler
- * subclass is not created directly by an application. Rather, the
- * first time a protocol name is encountered when constructing a
- * URL, the appropriate stream protocol handler is
- * automatically loaded.
- *
- * @author James Gosling
- * @see java.net.URL#URL(java.lang.String, java.lang.String, int, java.lang.String)
- * @since JDK1.0
- */
-public abstract class URLStreamHandler {
- /**
- * Opens a connection to the object referenced by the
- * URL argument.
- * This method should be overridden by a subclass.
- *
- *
If for the handler's protocol (such as HTTP or JAR), there
- * exists a public, specialized URLConnection subclass belonging
- * to one of the following packages or one of their subpackages:
- * java.lang, java.io, java.util, java.net, the connection
- * returned will be of that subclass. For example, for HTTP an
- * HttpURLConnection will be returned, and for JAR a
- * JarURLConnection will be returned.
- *
- * @param u the URL that this connects to.
- * @return a URLConnection object for the URL.
- * @exception IOException if an I/O error occurs while opening the
- * connection.
- */
-// abstract protected URLConnection openConnection(URL u) throws IOException;
-
- /**
- * Same as openConnection(URL), except that the connection will be
- * made through the specified proxy; Protocol handlers that do not
- * support proxying will ignore the proxy parameter and make a
- * normal connection.
- *
- * Calling this method preempts the system's default ProxySelector
- * settings.
- *
- * @param u the URL that this connects to.
- * @param p the proxy through which the connection will be made.
- * If direct connection is desired, Proxy.NO_PROXY
- * should be specified.
- * @return a URLConnection object for the URL.
- * @exception IOException if an I/O error occurs while opening the
- * connection.
- * @exception IllegalArgumentException if either u or p is null,
- * or p has the wrong type.
- * @exception UnsupportedOperationException if the subclass that
- * implements the protocol doesn't support this method.
- * @since 1.5
- */
-// protected URLConnection openConnection(URL u, Proxy p) throws IOException {
-// throw new UnsupportedOperationException("Method not implemented.");
-// }
-
- /**
- * Parses the string representation of a URL into a
- * URL object.
- *
- * If there is any inherited context, then it has already been
- * copied into the URL argument.
- *
- * The parseURL method of URLStreamHandler
- * parses the string representation as if it were an
- * http specification. Most URL protocol families have a
- * similar parsing. A stream protocol handler for a protocol that has
- * a different syntax must override this routine.
- *
- * @param u the URL to receive the result of parsing
- * the spec.
- * @param spec the String representing the URL that
- * must be parsed.
- * @param start the character index at which to begin parsing. This is
- * just past the ':' (if there is one) that
- * specifies the determination of the protocol name.
- * @param limit the character position to stop parsing at. This is the
- * end of the string or the position of the
- * "#" character, if present. All information
- * after the sharp sign indicates an anchor.
- */
- protected void parseURL(URL u, String spec, int start, int limit) {
- // These fields may receive context content if this was relative URL
- String protocol = u.getProtocol();
- String authority = u.getAuthority();
- String userInfo = u.getUserInfo();
- String host = u.getHost();
- int port = u.getPort();
- String path = u.getPath();
- String query = u.getQuery();
-
- // This field has already been parsed
- String ref = u.getRef();
-
- boolean isRelPath = false;
- boolean queryOnly = false;
-
-// FIX: should not assume query if opaque
- // Strip off the query part
- if (start < limit) {
- int queryStart = spec.indexOf('?');
- queryOnly = queryStart == start;
- if ((queryStart != -1) && (queryStart < limit)) {
- query = spec.substring(queryStart+1, limit);
- if (limit > queryStart)
- limit = queryStart;
- spec = spec.substring(0, queryStart);
- }
- }
-
- int i = 0;
- // Parse the authority part if any
- boolean isUNCName = (start <= limit - 4) &&
- (spec.charAt(start) == '/') &&
- (spec.charAt(start + 1) == '/') &&
- (spec.charAt(start + 2) == '/') &&
- (spec.charAt(start + 3) == '/');
- if (!isUNCName && (start <= limit - 2) && (spec.charAt(start) == '/') &&
- (spec.charAt(start + 1) == '/')) {
- start += 2;
- i = spec.indexOf('/', start);
- if (i < 0) {
- i = spec.indexOf('?', start);
- if (i < 0)
- i = limit;
- }
-
- host = authority = spec.substring(start, i);
-
- int ind = authority.indexOf('@');
- if (ind != -1) {
- userInfo = authority.substring(0, ind);
- host = authority.substring(ind+1);
- } else {
- userInfo = null;
- }
- if (host != null) {
- // If the host is surrounded by [ and ] then its an IPv6
- // literal address as specified in RFC2732
- if (host.length()>0 && (host.charAt(0) == '[')) {
- if ((ind = host.indexOf(']')) > 2) {
-
- String nhost = host ;
- host = nhost.substring(0,ind+1);
-// if (!IPAddressUtil.
-// isIPv6LiteralAddress(host.substring(1, ind))) {
-// throw new IllegalArgumentException(
-// "Invalid host: "+ host);
-// }
-
- port = -1 ;
- if (nhost.length() > ind+1) {
- if (nhost.charAt(ind+1) == ':') {
- ++ind ;
- // port can be null according to RFC2396
- if (nhost.length() > (ind + 1)) {
- port = Integer.parseInt(nhost.substring(ind+1));
- }
- } else {
- throw new IllegalArgumentException(
- "Invalid authority field: " + authority);
- }
- }
- } else {
- throw new IllegalArgumentException(
- "Invalid authority field: " + authority);
- }
- } else {
- ind = host.indexOf(':');
- port = -1;
- if (ind >= 0) {
- // port can be null according to RFC2396
- if (host.length() > (ind + 1)) {
- port = Integer.parseInt(host.substring(ind + 1));
- }
- host = host.substring(0, ind);
- }
- }
- } else {
- host = "";
- }
- if (port < -1)
- throw new IllegalArgumentException("Invalid port number :" +
- port);
- start = i;
- // If the authority is defined then the path is defined by the
- // spec only; See RFC 2396 Section 5.2.4.
- if (authority != null && authority.length() > 0)
- path = "";
- }
-
- if (host == null) {
- host = "";
- }
-
- // Parse the file path if any
- if (start < limit) {
- if (spec.charAt(start) == '/') {
- path = spec.substring(start, limit);
- } else if (path != null && path.length() > 0) {
- isRelPath = true;
- int ind = path.lastIndexOf('/');
- String seperator = "";
- if (ind == -1 && authority != null)
- seperator = "/";
- path = path.substring(0, ind + 1) + seperator +
- spec.substring(start, limit);
-
- } else {
- String seperator = (authority != null) ? "/" : "";
- path = seperator + spec.substring(start, limit);
- }
- } else if (queryOnly && path != null) {
- int ind = path.lastIndexOf('/');
- if (ind < 0)
- ind = 0;
- path = path.substring(0, ind) + "/";
- }
- if (path == null)
- path = "";
-
- if (isRelPath) {
- // Remove embedded /./
- while ((i = path.indexOf("/./")) >= 0) {
- path = path.substring(0, i) + path.substring(i + 2);
- }
- // Remove embedded /../ if possible
- i = 0;
- while ((i = path.indexOf("/../", i)) >= 0) {
- /*
- * A "/../" will cancel the previous segment and itself,
- * unless that segment is a "/../" itself
- * i.e. "/a/b/../c" becomes "/a/c"
- * but "/../../a" should stay unchanged
- */
- if (i > 0 && (limit = path.lastIndexOf('/', i - 1)) >= 0 &&
- (path.indexOf("/../", limit) != 0)) {
- path = path.substring(0, limit) + path.substring(i + 3);
- i = 0;
- } else {
- i = i + 3;
- }
- }
- // Remove trailing .. if possible
- while (path.endsWith("/..")) {
- i = path.indexOf("/..");
- if ((limit = path.lastIndexOf('/', i - 1)) >= 0) {
- path = path.substring(0, limit+1);
- } else {
- break;
- }
- }
- // Remove starting .
- if (path.startsWith("./") && path.length() > 2)
- path = path.substring(2);
-
- // Remove trailing .
- if (path.endsWith("/."))
- path = path.substring(0, path.length() -1);
- }
-
- setURL(u, protocol, host, port, authority, userInfo, path, query, ref);
- }
-
- /**
- * Returns the default port for a URL parsed by this handler. This method
- * is meant to be overidden by handlers with default port numbers.
- * @return the default port for a URL parsed by this handler.
- * @since 1.3
- */
- protected int getDefaultPort() {
- return -1;
- }
-
- /**
- * Provides the default equals calculation. May be overidden by handlers
- * for other protocols that have different requirements for equals().
- * This method requires that none of its arguments is null. This is
- * guaranteed by the fact that it is only called by java.net.URL class.
- * @param u1 a URL object
- * @param u2 a URL object
- * @return true if the two urls are
- * considered equal, ie. they refer to the same
- * fragment in the same file.
- * @since 1.3
- */
- protected boolean equals(URL u1, URL u2) {
- String ref1 = u1.getRef();
- String ref2 = u2.getRef();
- return (ref1 == ref2 || (ref1 != null && ref1.equals(ref2))) &&
- sameFile(u1, u2);
- }
-
- /**
- * Provides the default hash calculation. May be overidden by handlers for
- * other protocols that have different requirements for hashCode
- * calculation.
- * @param u a URL object
- * @return an int suitable for hash table indexing
- * @since 1.3
- */
- protected int hashCode(URL u) {
- int h = 0;
-
- // Generate the protocol part.
- String protocol = u.getProtocol();
- if (protocol != null)
- h += protocol.hashCode();
-
- // Generate the host part.
- Object addr = getHostAddress(u);
- if (addr != null) {
- h += addr.hashCode();
- } else {
- String host = u.getHost();
- if (host != null)
- h += host.toLowerCase().hashCode();
- }
-
- // Generate the file part.
- String file = u.getFile();
- if (file != null)
- h += file.hashCode();
-
- // Generate the port part.
- if (u.getPort() == -1)
- h += getDefaultPort();
- else
- h += u.getPort();
-
- // Generate the ref part.
- String ref = u.getRef();
- if (ref != null)
- h += ref.hashCode();
-
- return h;
- }
-
- /**
- * Compare two urls to see whether they refer to the same file,
- * i.e., having the same protocol, host, port, and path.
- * This method requires that none of its arguments is null. This is
- * guaranteed by the fact that it is only called indirectly
- * by java.net.URL class.
- * @param u1 a URL object
- * @param u2 a URL object
- * @return true if u1 and u2 refer to the same file
- * @since 1.3
- */
- protected boolean sameFile(URL u1, URL u2) {
- // Compare the protocols.
- if (!((u1.getProtocol() == u2.getProtocol()) ||
- (u1.getProtocol() != null &&
- u1.getProtocol().equalsIgnoreCase(u2.getProtocol()))))
- return false;
-
- // Compare the files.
- if (!(u1.getFile() == u2.getFile() ||
- (u1.getFile() != null && u1.getFile().equals(u2.getFile()))))
- return false;
-
- // Compare the ports.
- int port1, port2;
- port1 = (u1.getPort() != -1) ? u1.getPort() : u1.handler.getDefaultPort();
- port2 = (u2.getPort() != -1) ? u2.getPort() : u2.handler.getDefaultPort();
- if (port1 != port2)
- return false;
-
- // Compare the hosts.
- if (!hostsEqual(u1, u2))
- return false;
-
- return true;
- }
-
- /**
- * Get the IP address of our host. An empty host field or a DNS failure
- * will result in a null return.
- *
- * @param u a URL object
- * @return an InetAddress representing the host
- * IP address.
- * @since 1.3
- */
- private synchronized Object getHostAddress(URL u) {
- return u.hostAddress;
- }
-
- /**
- * Compares the host components of two URLs.
- * @param u1 the URL of the first host to compare
- * @param u2 the URL of the second host to compare
- * @return true if and only if they
- * are equal, false otherwise.
- * @since 1.3
- */
- protected boolean hostsEqual(URL u1, URL u2) {
- Object a1 = getHostAddress(u1);
- Object a2 = getHostAddress(u2);
- // if we have internet address for both, compare them
- if (a1 != null && a2 != null) {
- return a1.equals(a2);
- // else, if both have host names, compare them
- } else if (u1.getHost() != null && u2.getHost() != null)
- return u1.getHost().equalsIgnoreCase(u2.getHost());
- else
- return u1.getHost() == null && u2.getHost() == null;
- }
-
- /**
- * Converts a URL of a specific protocol to a
- * String.
- *
- * @param u the URL.
- * @return a string representation of the URL argument.
- */
- protected String toExternalForm(URL u) {
-
- // pre-compute length of StringBuffer
- int len = u.getProtocol().length() + 1;
- if (u.getAuthority() != null && u.getAuthority().length() > 0)
- len += 2 + u.getAuthority().length();
- if (u.getPath() != null) {
- len += u.getPath().length();
- }
- if (u.getQuery() != null) {
- len += 1 + u.getQuery().length();
- }
- if (u.getRef() != null)
- len += 1 + u.getRef().length();
-
- StringBuffer result = new StringBuffer(len);
- result.append(u.getProtocol());
- result.append(":");
- if (u.getAuthority() != null && u.getAuthority().length() > 0) {
- result.append("//");
- result.append(u.getAuthority());
- }
- if (u.getPath() != null) {
- result.append(u.getPath());
- }
- if (u.getQuery() != null) {
- result.append('?');
- result.append(u.getQuery());
- }
- if (u.getRef() != null) {
- result.append("#");
- result.append(u.getRef());
- }
- return result.toString();
- }
-
- /**
- * Sets the fields of the URL argument to the indicated values.
- * Only classes derived from URLStreamHandler are supposed to be able
- * to call the set method on a URL.
- *
- * @param u the URL to modify.
- * @param protocol the protocol name.
- * @param host the remote host value for the URL.
- * @param port the port on the remote machine.
- * @param authority the authority part for the URL.
- * @param userInfo the userInfo part of the URL.
- * @param path the path component of the URL.
- * @param query the query part for the URL.
- * @param ref the reference.
- * @exception SecurityException if the protocol handler of the URL is
- * different from this one
- * @see java.net.URL#set(java.lang.String, java.lang.String, int, java.lang.String, java.lang.String)
- * @since 1.3
- */
- protected void setURL(URL u, String protocol, String host, int port,
- String authority, String userInfo, String path,
- String query, String ref) {
- if (this != u.handler) {
- throw new SecurityException("handler for url different from " +
- "this handler");
- }
- // ensure that no one can reset the protocol on a given URL.
- u.set(u.getProtocol(), host, port, authority, userInfo, path, query, ref);
- }
-
- /**
- * Sets the fields of the URL argument to the indicated values.
- * Only classes derived from URLStreamHandler are supposed to be able
- * to call the set method on a URL.
- *
- * @param u the URL to modify.
- * @param protocol the protocol name. This value is ignored since 1.2.
- * @param host the remote host value for the URL.
- * @param port the port on the remote machine.
- * @param file the file.
- * @param ref the reference.
- * @exception SecurityException if the protocol handler of the URL is
- * different from this one
- * @deprecated Use setURL(URL, String, String, int, String, String, String,
- * String);
- */
- @Deprecated
- protected void setURL(URL u, String protocol, String host, int port,
- String file, String ref) {
- /*
- * Only old URL handlers call this, so assume that the host
- * field might contain "user:passwd@host". Fix as necessary.
- */
- String authority = null;
- String userInfo = null;
- if (host != null && host.length() != 0) {
- authority = (port == -1) ? host : host + ":" + port;
- int at = host.lastIndexOf('@');
- if (at != -1) {
- userInfo = host.substring(0, at);
- host = host.substring(at+1);
- }
- }
-
- /*
- * Assume file might contain query part. Fix as necessary.
- */
- String path = null;
- String query = null;
- if (file != null) {
- int q = file.lastIndexOf('?');
- if (q != -1) {
- query = file.substring(q+1);
- path = file.substring(0, q);
- } else
- path = file;
- }
- setURL(u, protocol, host, port, authority, userInfo, path, query, ref);
- }
-}