jaroslav@557: /*
jaroslav@557:  * Copyright (c) 1996, 2005, Oracle and/or its affiliates. All rights reserved.
jaroslav@557:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
jaroslav@557:  *
jaroslav@557:  * This code is free software; you can redistribute it and/or modify it
jaroslav@557:  * under the terms of the GNU General Public License version 2 only, as
jaroslav@557:  * published by the Free Software Foundation.  Oracle designates this
jaroslav@557:  * particular file as subject to the "Classpath" exception as provided
jaroslav@557:  * by Oracle in the LICENSE file that accompanied this code.
jaroslav@557:  *
jaroslav@557:  * This code is distributed in the hope that it will be useful, but WITHOUT
jaroslav@557:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
jaroslav@557:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
jaroslav@557:  * version 2 for more details (a copy is included in the LICENSE file that
jaroslav@557:  * accompanied this code).
jaroslav@557:  *
jaroslav@557:  * You should have received a copy of the GNU General Public License version
jaroslav@557:  * 2 along with this work; if not, write to the Free Software Foundation,
jaroslav@557:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
jaroslav@557:  *
jaroslav@557:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
jaroslav@557:  * or visit www.oracle.com if you need additional information or have any
jaroslav@557:  * questions.
jaroslav@557:  */
jaroslav@557: 
jaroslav@557: package java.io;
jaroslav@557: 
jaroslav@557: import java.nio.charset.Charset;
jaroslav@557: import java.nio.charset.CharsetDecoder;
jaroslav@557: import sun.nio.cs.StreamDecoder;
jaroslav@557: 
jaroslav@557: 
jaroslav@557: /**
jaroslav@557:  * An InputStreamReader is a bridge from byte streams to character streams: It
jaroslav@557:  * reads bytes and decodes them into characters using a specified {@link
jaroslav@557:  * java.nio.charset.Charset <code>charset</code>}.  The charset that it uses
jaroslav@557:  * may be specified by name or may be given explicitly, or the platform's
jaroslav@557:  * default charset may be accepted.
jaroslav@557:  *
jaroslav@557:  * <p> Each invocation of one of an InputStreamReader's read() methods may
jaroslav@557:  * cause one or more bytes to be read from the underlying byte-input stream.
jaroslav@557:  * To enable the efficient conversion of bytes to characters, more bytes may
jaroslav@557:  * be read ahead from the underlying stream than are necessary to satisfy the
jaroslav@557:  * current read operation.
jaroslav@557:  *
jaroslav@557:  * <p> For top efficiency, consider wrapping an InputStreamReader within a
jaroslav@557:  * BufferedReader.  For example:
jaroslav@557:  *
jaroslav@557:  * <pre>
jaroslav@557:  * BufferedReader in
jaroslav@557:  *   = new BufferedReader(new InputStreamReader(System.in));
jaroslav@557:  * </pre>
jaroslav@557:  *
jaroslav@557:  * @see BufferedReader
jaroslav@557:  * @see InputStream
jaroslav@557:  * @see java.nio.charset.Charset
jaroslav@557:  *
jaroslav@557:  * @author      Mark Reinhold
jaroslav@557:  * @since       JDK1.1
jaroslav@557:  */
jaroslav@557: 
jaroslav@557: public class InputStreamReader extends Reader {
jaroslav@557: 
jaroslav@557:     private final StreamDecoder sd;
jaroslav@557: 
jaroslav@557:     /**
jaroslav@557:      * Creates an InputStreamReader that uses the default charset.
jaroslav@557:      *
jaroslav@557:      * @param  in   An InputStream
jaroslav@557:      */
jaroslav@557:     public InputStreamReader(InputStream in) {
jaroslav@557:         super(in);
jaroslav@557:         try {
jaroslav@557:             sd = StreamDecoder.forInputStreamReader(in, this, (String)null); // ## check lock object
jaroslav@557:         } catch (UnsupportedEncodingException e) {
jaroslav@557:             // The default encoding should always be available
jaroslav@557:             throw new Error(e);
jaroslav@557:         }
jaroslav@557:     }
jaroslav@557: 
jaroslav@557:     /**
jaroslav@557:      * Creates an InputStreamReader that uses the named charset.
jaroslav@557:      *
jaroslav@557:      * @param  in
jaroslav@557:      *         An InputStream
jaroslav@557:      *
jaroslav@557:      * @param  charsetName
jaroslav@557:      *         The name of a supported
jaroslav@557:      *         {@link java.nio.charset.Charset </code>charset<code>}
jaroslav@557:      *
jaroslav@557:      * @exception  UnsupportedEncodingException
jaroslav@557:      *             If the named charset is not supported
jaroslav@557:      */
jaroslav@557:     public InputStreamReader(InputStream in, String charsetName)
jaroslav@557:         throws UnsupportedEncodingException
jaroslav@557:     {
jaroslav@557:         super(in);
jaroslav@557:         if (charsetName == null)
jaroslav@557:             throw new NullPointerException("charsetName");
jaroslav@557:         sd = StreamDecoder.forInputStreamReader(in, this, charsetName);
jaroslav@557:     }
jaroslav@557: 
jaroslav@557:     /**
jaroslav@557:      * Creates an InputStreamReader that uses the given charset. </p>
jaroslav@557:      *
jaroslav@557:      * @param  in       An InputStream
jaroslav@557:      * @param  cs       A charset
jaroslav@557:      *
jaroslav@557:      * @since 1.4
jaroslav@557:      * @spec JSR-51
jaroslav@557:      */
jaroslav@560: /* XXX:
jaroslav@557:     public InputStreamReader(InputStream in, Charset cs) {
jaroslav@557:         super(in);
jaroslav@557:         if (cs == null)
jaroslav@557:             throw new NullPointerException("charset");
jaroslav@557:         sd = StreamDecoder.forInputStreamReader(in, this, cs);
jaroslav@557:     }
jaroslav@560: */
jaroslav@557:     /**
jaroslav@557:      * Creates an InputStreamReader that uses the given charset decoder.  </p>
jaroslav@557:      *
jaroslav@557:      * @param  in       An InputStream
jaroslav@557:      * @param  dec      A charset decoder
jaroslav@557:      *
jaroslav@557:      * @since 1.4
jaroslav@557:      * @spec JSR-51
jaroslav@557:      */
jaroslav@560: /* XXX:
jaroslav@557:     public InputStreamReader(InputStream in, CharsetDecoder dec) {
jaroslav@557:         super(in);
jaroslav@557:         if (dec == null)
jaroslav@557:             throw new NullPointerException("charset decoder");
jaroslav@557:         sd = StreamDecoder.forInputStreamReader(in, this, dec);
jaroslav@557:     }
jaroslav@560: */
jaroslav@560:     
jaroslav@557:     /**
jaroslav@557:      * Returns the name of the character encoding being used by this stream.
jaroslav@557:      *
jaroslav@557:      * <p> If the encoding has an historical name then that name is returned;
jaroslav@557:      * otherwise the encoding's canonical name is returned.
jaroslav@557:      *
jaroslav@557:      * <p> If this instance was created with the {@link
jaroslav@557:      * #InputStreamReader(InputStream, String)} constructor then the returned
jaroslav@557:      * name, being unique for the encoding, may differ from the name passed to
jaroslav@557:      * the constructor. This method will return <code>null</code> if the
jaroslav@557:      * stream has been closed.
jaroslav@557:      * </p>
jaroslav@557:      * @return The historical name of this encoding, or
jaroslav@557:      *         <code>null</code> if the stream has been closed
jaroslav@557:      *
jaroslav@557:      * @see java.nio.charset.Charset
jaroslav@557:      *
jaroslav@557:      * @revised 1.4
jaroslav@557:      * @spec JSR-51
jaroslav@557:      */
jaroslav@557:     public String getEncoding() {
jaroslav@557:         return sd.getEncoding();
jaroslav@557:     }
jaroslav@557: 
jaroslav@557:     /**
jaroslav@557:      * Reads a single character.
jaroslav@557:      *
jaroslav@557:      * @return The character read, or -1 if the end of the stream has been
jaroslav@557:      *         reached
jaroslav@557:      *
jaroslav@557:      * @exception  IOException  If an I/O error occurs
jaroslav@557:      */
jaroslav@557:     public int read() throws IOException {
jaroslav@557:         return sd.read();
jaroslav@557:     }
jaroslav@557: 
jaroslav@557:     /**
jaroslav@557:      * Reads characters into a portion of an array.
jaroslav@557:      *
jaroslav@557:      * @param      cbuf     Destination buffer
jaroslav@557:      * @param      offset   Offset at which to start storing characters
jaroslav@557:      * @param      length   Maximum number of characters to read
jaroslav@557:      *
jaroslav@557:      * @return     The number of characters read, or -1 if the end of the
jaroslav@557:      *             stream has been reached
jaroslav@557:      *
jaroslav@557:      * @exception  IOException  If an I/O error occurs
jaroslav@557:      */
jaroslav@557:     public int read(char cbuf[], int offset, int length) throws IOException {
jaroslav@557:         return sd.read(cbuf, offset, length);
jaroslav@557:     }
jaroslav@557: 
jaroslav@557:     /**
jaroslav@557:      * Tells whether this stream is ready to be read.  An InputStreamReader is
jaroslav@557:      * ready if its input buffer is not empty, or if bytes are available to be
jaroslav@557:      * read from the underlying byte stream.
jaroslav@557:      *
jaroslav@557:      * @exception  IOException  If an I/O error occurs
jaroslav@557:      */
jaroslav@557:     public boolean ready() throws IOException {
jaroslav@557:         return sd.ready();
jaroslav@557:     }
jaroslav@557: 
jaroslav@557:     public void close() throws IOException {
jaroslav@557:         sd.close();
jaroslav@557:     }
jaroslav@557: }