1 /* 2 * Copyright (c) 1996, 2006, 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 29 /** 30 * Piped character-output streams. 31 * 32 * @author Mark Reinhold 33 * @since JDK1.1 34 */ 35 36 public class PipedWriter extends Writer { 37 38 /* REMIND: identification of the read and write sides needs to be 39 more sophisticated. Either using thread groups (but what about 40 pipes within a thread?) or using finalization (but it may be a 41 long time until the next GC). */ 42 private PipedReader sink; 43 44 /* This flag records the open status of this particular writer. It 45 * is independent of the status flags defined in PipedReader. It is 46 * used to do a sanity check on connect. 47 */ 48 private boolean closed = false; 49 50 /** 51 * Creates a piped writer connected to the specified piped 52 * reader. Data characters written to this stream will then be 53 * available as input from <code>snk</code>. 54 * 55 * @param snk The piped reader to connect to. 56 * @exception IOException if an I/O error occurs. 57 */ 58 public PipedWriter(PipedReader snk) throws IOException { 59 connect(snk); 60 } 61 62 /** 63 * Creates a piped writer that is not yet connected to a 64 * piped reader. It must be connected to a piped reader, 65 * either by the receiver or the sender, before being used. 66 * 67 * @see java.io.PipedReader#connect(java.io.PipedWriter) 68 * @see java.io.PipedWriter#connect(java.io.PipedReader) 69 */ 70 public PipedWriter() { 71 } 72 73 /** 74 * Connects this piped writer to a receiver. If this object 75 * is already connected to some other piped reader, an 76 * <code>IOException</code> is thrown. 77 * <p> 78 * If <code>snk</code> is an unconnected piped reader and 79 * <code>src</code> is an unconnected piped writer, they may 80 * be connected by either the call: 81 * <blockquote><pre> 82 * src.connect(snk)</pre></blockquote> 83 * or the call: 84 * <blockquote><pre> 85 * snk.connect(src)</pre></blockquote> 86 * The two calls have the same effect. 87 * 88 * @param snk the piped reader to connect to. 89 * @exception IOException if an I/O error occurs. 90 */ 91 public synchronized void connect(PipedReader snk) throws IOException { 92 if (snk == null) { 93 throw new NullPointerException(); 94 } else if (sink != null || snk.connected) { 95 throw new IOException("Already connected"); 96 } else if (snk.closedByReader || closed) { 97 throw new IOException("Pipe closed"); 98 } 99 100 sink = snk; 101 snk.in = -1; 102 snk.out = 0; 103 snk.connected = true; 104 } 105 106 /** 107 * Writes the specified <code>char</code> to the piped output stream. 108 * If a thread was reading data characters from the connected piped input 109 * stream, but the thread is no longer alive, then an 110 * <code>IOException</code> is thrown. 111 * <p> 112 * Implements the <code>write</code> method of <code>Writer</code>. 113 * 114 * @param c the <code>char</code> to be written. 115 * @exception IOException if the pipe is 116 * <a href=PipedOutputStream.html#BROKEN> <code>broken</code></a>, 117 * {@link #connect(java.io.PipedReader) unconnected}, closed 118 * or an I/O error occurs. 119 */ 120 public void write(int c) throws IOException { 121 if (sink == null) { 122 throw new IOException("Pipe not connected"); 123 } 124 sink.receive(c); 125 } 126 127 /** 128 * Writes <code>len</code> characters from the specified character array 129 * starting at offset <code>off</code> to this piped output stream. 130 * This method blocks until all the characters are written to the output 131 * stream. 132 * If a thread was reading data characters from the connected piped input 133 * stream, but the thread is no longer alive, then an 134 * <code>IOException</code> is thrown. 135 * 136 * @param cbuf the data. 137 * @param off the start offset in the data. 138 * @param len the number of characters to write. 139 * @exception IOException if the pipe is 140 * <a href=PipedOutputStream.html#BROKEN> <code>broken</code></a>, 141 * {@link #connect(java.io.PipedReader) unconnected}, closed 142 * or an I/O error occurs. 143 */ 144 public void write(char cbuf[], int off, int len) throws IOException { 145 if (sink == null) { 146 throw new IOException("Pipe not connected"); 147 } else if ((off | len | (off + len) | (cbuf.length - (off + len))) < 0) { 148 throw new IndexOutOfBoundsException(); 149 } 150 sink.receive(cbuf, off, len); 151 } 152 153 /** 154 * Flushes this output stream and forces any buffered output characters 155 * to be written out. 156 * This will notify any readers that characters are waiting in the pipe. 157 * 158 * @exception IOException if the pipe is closed, or an I/O error occurs. 159 */ 160 public synchronized void flush() throws IOException { 161 if (sink != null) { 162 if (sink.closedByReader || closed) { 163 throw new IOException("Pipe closed"); 164 } 165 synchronized (sink) { 166 sink.notifyAll(); 167 } 168 } 169 } 170 171 /** 172 * Closes this piped output stream and releases any system resources 173 * associated with this stream. This stream may no longer be used for 174 * writing characters. 175 * 176 * @exception IOException if an I/O error occurs. 177 */ 178 public void close() throws IOException { 179 closed = true; 180 if (sink != null) { 181 sink.receivedLast(); 182 } 183 } 184 } 185
