1 /*
2 * Copyright (c) 1996, 2016, 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.CharBuffer;
29 import java.nio.charset.Charset;
30 import java.nio.charset.CharsetEncoder;
31 import sun.nio.cs.StreamEncoder;
32
33
34 /**
35 * An OutputStreamWriter is a bridge from character streams to byte streams:
36 * Characters written to it are encoded into bytes using a specified {@link
37 * java.nio.charset.Charset charset}. The charset that it uses
38 * may be specified by name or may be given explicitly, or the platform's
39 * default charset may be accepted.
40 *
41 * <p> Each invocation of a write() method causes the encoding converter to be
42 * invoked on the given character(s). The resulting bytes are accumulated in a
43 * buffer before being written to the underlying output stream. The size of
44 * this buffer may be specified, but by default it is large enough for most
45 * purposes. Note that the characters passed to the write() methods are not
46 * buffered.
47 *
48 * <p> For top efficiency, consider wrapping an OutputStreamWriter within a
49 * BufferedWriter so as to avoid frequent converter invocations. For example:
50 *
51 * <pre>
52 * Writer out
53 * = new BufferedWriter(new OutputStreamWriter(System.out));
54 * </pre>
55 *
56 * <p> A <i>surrogate pair</i> is a character represented by a sequence of two
57 * {@code char} values: A <i>high</i> surrogate in the range '\uD800' to
58 * '\uDBFF' followed by a <i>low</i> surrogate in the range '\uDC00' to
59 * '\uDFFF'.
60 *
61 * <p> A <i>malformed surrogate element</i> is a high surrogate that is not
62 * followed by a low surrogate or a low surrogate that is not preceded by a
63 * high surrogate.
64 *
65 * <p> This class always replaces malformed surrogate elements and unmappable
66 * character sequences with the charset's default <i>substitution sequence</i>.
67 * The {@linkplain java.nio.charset.CharsetEncoder} class should be used when more
68 * control over the encoding process is required.
69 *
70 * @see BufferedWriter
71 * @see OutputStream
72 * @see java.nio.charset.Charset
73 *
74 * @author Mark Reinhold
75 * @since 1.1
76 */
77
78 public class OutputStreamWriter extends Writer {
79
80 private final StreamEncoder se;
81
82 /**
83 * Creates an OutputStreamWriter that uses the named charset.
84 *
85 * @param out
86 * An OutputStream
87 *
88 * @param charsetName
89 * The name of a supported
90 * {@link java.nio.charset.Charset charset}
91 *
92 * @exception UnsupportedEncodingException
93 * If the named encoding is not supported
94 */
95 public OutputStreamWriter(OutputStream out, String charsetName)
96 throws UnsupportedEncodingException
97 {
98 super(out);
99 if (charsetName == null)
100 throw new NullPointerException("charsetName");
101 se = StreamEncoder.forOutputStreamWriter(out, this, charsetName);
102 }
103
104 /**
105 * Creates an OutputStreamWriter that uses the default character encoding.
106 *
107 * @param out An OutputStream
108 */
109 public OutputStreamWriter(OutputStream out) {
110 super(out);
111 try {
112 se = StreamEncoder.forOutputStreamWriter(out, this, (String)null);
113 } catch (UnsupportedEncodingException e) {
114 throw new Error(e);
115 }
116 }
117
118 /**
119 * Creates an OutputStreamWriter that uses the given charset.
120 *
121 * @param out
122 * An OutputStream
123 *
124 * @param cs
125 * A charset
126 *
127 * @since 1.4
128 * @spec JSR-51
129 */
130 public OutputStreamWriter(OutputStream out, Charset cs) {
131 super(out);
132 if (cs == null)
133 throw new NullPointerException("charset");
134 se = StreamEncoder.forOutputStreamWriter(out, this, cs);
135 }
136
137 /**
138 * Creates an OutputStreamWriter that uses the given charset encoder.
139 *
140 * @param out
141 * An OutputStream
142 *
143 * @param enc
144 * A charset encoder
145 *
146 * @since 1.4
147 * @spec JSR-51
148 */
149 public OutputStreamWriter(OutputStream out, CharsetEncoder enc) {
150 super(out);
151 if (enc == null)
152 throw new NullPointerException("charset encoder");
153 se = StreamEncoder.forOutputStreamWriter(out, this, enc);
154 }
155
156 /**
157 * Returns the name of the character encoding being used by this stream.
158 *
159 * <p> If the encoding has an historical name then that name is returned;
160 * otherwise the encoding's canonical name is returned.
161 *
162 * <p> If this instance was created with the {@link
163 * #OutputStreamWriter(OutputStream, String)} constructor then the returned
164 * name, being unique for the encoding, may differ from the name passed to
165 * the constructor. This method may return {@code null} if the stream has
166 * been closed. </p>
167 *
168 * @return The historical name of this encoding, or possibly
169 * <code>null</code> if the stream has been closed
170 *
171 * @see java.nio.charset.Charset
172 *
173 * @revised 1.4
174 * @spec JSR-51
175 */
176 public String getEncoding() {
177 return se.getEncoding();
178 }
179
180 /**
181 * Flushes the output buffer to the underlying byte stream, without flushing
182 * the byte stream itself. This method is non-private only so that it may
183 * be invoked by PrintStream.
184 */
185 void flushBuffer() throws IOException {
186 se.flushBuffer();
187 }
188
189 /**
190 * Writes a single character.
191 *
192 * @exception IOException If an I/O error occurs
193 */
194 public void write(int c) throws IOException {
195 se.write(c);
196 }
197
198 /**
199 * Writes a portion of an array of characters.
200 *
201 * @param cbuf Buffer of characters
202 * @param off Offset from which to start writing characters
203 * @param len Number of characters to write
204 *
205 * @throws IndexOutOfBoundsException
206 * If {@code off} is negative, or {@code len} is negative,
207 * or {@code off + len} is negative or greater than the length
208 * of the given array
209 *
210 * @throws IOException If an I/O error occurs
211 */
212 public void write(char cbuf[], int off, int len) throws IOException {
213 se.write(cbuf, off, len);
214 }
215
216 /**
217 * Writes a portion of a string.
218 *
219 * @param str A String
220 * @param off Offset from which to start writing characters
221 * @param len Number of characters to write
222 *
223 * @throws IndexOutOfBoundsException
224 * If {@code off} is negative, or {@code len} is negative,
225 * or {@code off + len} is negative or greater than the length
226 * of the given string
227 *
228 * @throws IOException If an I/O error occurs
229 */
230 public void write(String str, int off, int len) throws IOException {
231 se.write(str, off, len);
232 }
233
234 @Override
235 public Writer append(CharSequence csq, int start, int end) throws IOException {
236 if (csq == null) csq = "null";
237 write(csq.subSequence(start, end).toString());
238 return this;
239 }
240
241 @Override
242 public Writer append(CharSequence csq) throws IOException {
243 if (csq instanceof CharBuffer) {
244 se.write((CharBuffer) csq);
245 } else {
246 se.write(String.valueOf(csq));
247 }
248 return this;
249 }
250
251 /**
252 * Flushes the stream.
253 *
254 * @exception IOException If an I/O error occurs
255 */
256 public void flush() throws IOException {
257 se.flush();
258 }
259
260 public void close() throws IOException {
261 se.close();
262 }
263 }