2 * Copyright (c) 1996, 2005, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
28 import java.nio.charset.Charset;
29 import java.nio.charset.CharsetDecoder;
30 import sun.nio.cs.StreamDecoder;
34 * An InputStreamReader is a bridge from byte streams to character streams: It
35 * reads bytes and decodes them into characters using a specified {@link
36 * java.nio.charset.Charset <code>charset</code>}. The charset that it uses
37 * may be specified by name or may be given explicitly, or the platform's
38 * default charset may be accepted.
40 * <p> Each invocation of one of an InputStreamReader's read() methods may
41 * cause one or more bytes to be read from the underlying byte-input stream.
42 * To enable the efficient conversion of bytes to characters, more bytes may
43 * be read ahead from the underlying stream than are necessary to satisfy the
44 * current read operation.
46 * <p> For top efficiency, consider wrapping an InputStreamReader within a
47 * BufferedReader. For example:
51 * = new BufferedReader(new InputStreamReader(System.in));
56 * @see java.nio.charset.Charset
58 * @author Mark Reinhold
62 public class InputStreamReader extends Reader {
64 private final StreamDecoder sd;
67 * Creates an InputStreamReader that uses the default charset.
69 * @param in An InputStream
71 public InputStreamReader(InputStream in) {
74 sd = StreamDecoder.forInputStreamReader(in, this, (String)null); // ## check lock object
75 } catch (UnsupportedEncodingException e) {
76 // The default encoding should always be available
82 * Creates an InputStreamReader that uses the named charset.
88 * The name of a supported
89 * {@link java.nio.charset.Charset </code>charset<code>}
91 * @exception UnsupportedEncodingException
92 * If the named charset is not supported
94 public InputStreamReader(InputStream in, String charsetName)
95 throws UnsupportedEncodingException
98 if (charsetName == null)
99 throw new NullPointerException("charsetName");
100 sd = StreamDecoder.forInputStreamReader(in, this, charsetName);
104 * Creates an InputStreamReader that uses the given charset. </p>
106 * @param in An InputStream
107 * @param cs A charset
112 public InputStreamReader(InputStream in, Charset cs) {
115 throw new NullPointerException("charset");
116 sd = StreamDecoder.forInputStreamReader(in, this, cs);
120 * Creates an InputStreamReader that uses the given charset decoder. </p>
122 * @param in An InputStream
123 * @param dec A charset decoder
128 public InputStreamReader(InputStream in, CharsetDecoder dec) {
131 throw new NullPointerException("charset decoder");
132 sd = StreamDecoder.forInputStreamReader(in, this, dec);
136 * Returns the name of the character encoding being used by this stream.
138 * <p> If the encoding has an historical name then that name is returned;
139 * otherwise the encoding's canonical name is returned.
141 * <p> If this instance was created with the {@link
142 * #InputStreamReader(InputStream, String)} constructor then the returned
143 * name, being unique for the encoding, may differ from the name passed to
144 * the constructor. This method will return <code>null</code> if the
145 * stream has been closed.
147 * @return The historical name of this encoding, or
148 * <code>null</code> if the stream has been closed
150 * @see java.nio.charset.Charset
155 public String getEncoding() {
156 return sd.getEncoding();
160 * Reads a single character.
162 * @return The character read, or -1 if the end of the stream has been
165 * @exception IOException If an I/O error occurs
167 public int read() throws IOException {
172 * Reads characters into a portion of an array.
174 * @param cbuf Destination buffer
175 * @param offset Offset at which to start storing characters
176 * @param length Maximum number of characters to read
178 * @return The number of characters read, or -1 if the end of the
179 * stream has been reached
181 * @exception IOException If an I/O error occurs
183 public int read(char cbuf[], int offset, int length) throws IOException {
184 return sd.read(cbuf, offset, length);
188 * Tells whether this stream is ready to be read. An InputStreamReader is
189 * ready if its input buffer is not empty, or if bytes are available to be
190 * read from the underlying byte stream.
192 * @exception IOException If an I/O error occurs
194 public boolean ready() throws IOException {
198 public void close() throws IOException {