1 /*
2 * Copyright (c) 1996, 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
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.
10 *
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).
16 *
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.
20 *
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
23 * questions.
24 */
25
26 package java.io;
27
28 import java.nio.charset.Charset;
29 import java.nio.charset.CharsetEncoder;
30 import sun.nio.cs.StreamEncoder;
31
32
33 /**
34 * An OutputStreamWriter is a bridge from character streams to byte streams:
35 * Characters written to it are encoded into bytes using a specified {@link
36 * java.nio.charset.Charset charset}. 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.
39 *
40 * <p> Each invocation of a write() method causes the encoding converter to be
41 * invoked on the given character(s). The resulting bytes are accumulated in a
42 * buffer before being written to the underlying output stream. The size of
43 * this buffer may be specified, but by default it is large enough for most
44 * purposes. Note that the characters passed to the write() methods are not
45 * buffered.
46 *
47 * <p> For top efficiency, consider wrapping an OutputStreamWriter within a
48 * BufferedWriter so as to avoid frequent converter invocations. For example:
49 *
50 * <pre>
51 * Writer out
52 * = new BufferedWriter(new OutputStreamWriter(System.out));
53 * </pre>
54 *
55 * <p> A <i>surrogate pair</i> is a character represented by a sequence of two
56 * <tt>char</tt> values: A <i>high</i> surrogate in the range '\uD800' to
57 * '\uDBFF' followed by a <i>low</i> surrogate in the range '\uDC00' to
58 * '\uDFFF'.
59 *
60 * <p> A <i>malformed surrogate element</i> is a high surrogate that is not
61 * followed by a low surrogate or a low surrogate that is not preceded by a
62 * high surrogate.
63 *
64 * <p> This class always replaces malformed surrogate elements and unmappable
65 * character sequences with the charset's default <i>substitution sequence</i>.
66 * The {@linkplain java.nio.charset.CharsetEncoder} class should be used when more
67 * control over the encoding process is required.
68 *
69 * @see BufferedWriter
70 * @see OutputStream
71 * @see java.nio.charset.Charset
72 *
73 * @author Mark Reinhold
74 * @since 1.1
75 */
76
77 public class OutputStreamWriter extends Writer {
78
79 private final StreamEncoder se;
80
81 /**
82 * Creates an OutputStreamWriter that uses the named charset.
83 *
84 * @param out
85 * An OutputStream
86 *
87 * @param charsetName
88 * The name of a supported
89 * {@link java.nio.charset.Charset charset}
90 *
91 * @exception UnsupportedEncodingException
92 * If the named encoding is not supported
93 */
94 public OutputStreamWriter(OutputStream out, String charsetName)
95 throws UnsupportedEncodingException
96 {
97 super(out);
98 if (charsetName == null)
99 throw new NullPointerException("charsetName");
100 se = StreamEncoder.forOutputStreamWriter(out, this, charsetName);
101 }
102
103 /**
104 * Creates an OutputStreamWriter that uses the default character encoding.
105 *
106 * @param out An OutputStream
107 */
108 public OutputStreamWriter(OutputStream out) {
109 super(out);
110 try {
111 se = StreamEncoder.forOutputStreamWriter(out, this, (String)null);
112 } catch (UnsupportedEncodingException e) {
113 throw new Error(e);
114 }
115 }
116
117 /**
118 * Creates an OutputStreamWriter that uses the given charset.
119 *
120 * @param out
121 * An OutputStream
122 *
123 * @param cs
124 * A charset
125 *
126 * @since 1.4
127 * @spec JSR-51
128 */
129 public OutputStreamWriter(OutputStream out, Charset cs) {
130 super(out);
131 if (cs == null)
132 throw new NullPointerException("charset");
133 se = StreamEncoder.forOutputStreamWriter(out, this, cs);
134 }
135
136 /**
137 * Creates an OutputStreamWriter that uses the given charset encoder.
138 *
139 * @param out
140 * An OutputStream
141 *
142 * @param enc
143 * A charset encoder
144 *
145 * @since 1.4
146 * @spec JSR-51
147 */
148 public OutputStreamWriter(OutputStream out, CharsetEncoder enc) {
149 super(out);
150 if (enc == null)
151 throw new NullPointerException("charset encoder");
152 se = StreamEncoder.forOutputStreamWriter(out, this, enc);
153 }
154
155 /**
156 * Returns the name of the character encoding being used by this stream.
157 *
158 * <p> If the encoding has an historical name then that name is returned;
159 * otherwise the encoding's canonical name is returned.
160 *
161 * <p> If this instance was created with the {@link
162 * #OutputStreamWriter(OutputStream, String)} constructor then the returned
163 * name, being unique for the encoding, may differ from the name passed to
164 * the constructor. This method may return <tt>null</tt> if the stream has
165 * been closed. </p>
166 *
167 * @return The historical name of this encoding, or possibly
168 * <code>null</code> if the stream has been closed
169 *
170 * @see java.nio.charset.Charset
171 *
172 * @revised 1.4
173 * @spec JSR-51
174 */
175 public String getEncoding() {
176 return se.getEncoding();
177 }
178
179 /**
180 * Flushes the output buffer to the underlying byte stream, without flushing
181 * the byte stream itself. This method is non-private only so that it may
182 * be invoked by PrintStream.
183 */
184 void flushBuffer() throws IOException {
185 se.flushBuffer();
186 }
187
188 /**
189 * Writes a single character.
190 *
191 * @exception IOException If an I/O error occurs
192 */
193 public void write(int c) throws IOException {
194 se.write(c);
195 }
196
197 /**
198 * Writes a portion of an array of characters.
199 *
200 * @param cbuf Buffer of characters
201 * @param off Offset from which to start writing characters
202 * @param len Number of characters to write
203 *
204 * @exception IOException If an I/O error occurs
205 */
206 public void write(char cbuf[], int off, int len) throws IOException {
207 se.write(cbuf, off, len);
208 }
209
210 /**
211 * Writes a portion of a string.
212 *
213 * @param str A String
214 * @param off Offset from which to start writing characters
215 * @param len Number of characters to write
216 *
217 * @exception IOException If an I/O error occurs
218 */
219 public void write(String str, int off, int len) throws IOException {
220 se.write(str, off, len);
221 }
222
223 /**
224 * Flushes the stream.
225 *
226 * @exception IOException If an I/O error occurs
227 */
228 public void flush() throws IOException {
229 se.flush();
230 }
231
232 public void close() throws IOException {
233 se.close();
234 }
235 }