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1: /* PipedOutputStream.java -- Write portion of piped streams. 2: Copyright (C) 1998, 2000, 2001, 2003 Free Software Foundation, Inc. 3: 4: This file is part of GNU Classpath. 5: 6: GNU Classpath is free software; you can redistribute it and/or modify 7: it under the terms of the GNU General Public License as published by 8: the Free Software Foundation; either version 2, or (at your option) 9: any later version. 10: 11: GNU Classpath is distributed in the hope that it will be useful, but 12: WITHOUT ANY WARRANTY; without even the implied warranty of 13: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14: General Public License for more details. 15: 16: You should have received a copy of the GNU General Public License 17: along with GNU Classpath; see the file COPYING. If not, write to the 18: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 19: 02110-1301 USA. 20: 21: Linking this library statically or dynamically with other modules is 22: making a combined work based on this library. Thus, the terms and 23: conditions of the GNU General Public License cover the whole 24: combination. 25: 26: As a special exception, the copyright holders of this library give you 27: permission to link this library with independent modules to produce an 28: executable, regardless of the license terms of these independent 29: modules, and to copy and distribute the resulting executable under 30: terms of your choice, provided that you also meet, for each linked 31: independent module, the terms and conditions of the license of that 32: module. An independent module is a module which is not derived from 33: or based on this library. If you modify this library, you may extend 34: this exception to your version of the library, but you are not 35: obligated to do so. If you do not wish to do so, delete this 36: exception statement from your version. */ 37: 38: 39: package java.io; 40: 41: // NOTE: This implementation is very similar to that of PipedWriter. If you 42: // fix a bug in here, chances are you should make a similar change to the 43: // PipedWriter code. 44: 45: /** 46: * This class writes its bytes to a <code>PipedInputStream</code> to 47: * which it is connected. 48: * <p> 49: * It is highly recommended that a <code>PipedOutputStream</code> and its 50: * connected <code>PipedInputStream</code> be in different threads. If 51: * they are in the same thread, read and write operations could deadlock 52: * the thread. 53: * 54: * @author Aaron M. Renn (arenn@urbanophile.com) 55: */ 56: public class PipedOutputStream extends OutputStream 57: { 58: /** Target PipedInputStream to which this is connected. Null only if this 59: * OutputStream hasn't been connected yet. */ 60: PipedInputStream sink; 61: 62: /** Set to true if close() has been called on this OutputStream. */ 63: boolean closed; 64: 65: /** 66: * Create an unconnected PipedOutputStream. It must be connected 67: * to a <code>PipedInputStream</code> using the <code>connect</code> 68: * method prior to writing any data or an exception will be thrown. 69: */ 70: public PipedOutputStream() 71: { 72: } 73: 74: /** 75: * Create a new <code>PipedOutputStream</code> instance 76: * to write to the specified <code>PipedInputStream</code>. This stream 77: * is then ready for writing. 78: * 79: * @param sink The <code>PipedInputStream</code> to connect this stream to. 80: * 81: * @exception IOException If <code>sink</code> has already been connected 82: * to a different PipedOutputStream. 83: */ 84: public PipedOutputStream(PipedInputStream sink) throws IOException 85: { 86: sink.connect(this); 87: } 88: 89: /** 90: * Connects this object to the specified <code>PipedInputStream</code> 91: * object. This stream will then be ready for writing. 92: * 93: * @param sink The <code>PipedInputStream</code> to connect this stream to 94: * 95: * @exception IOException If the stream has not been connected or has 96: * been closed. 97: */ 98: public void connect(PipedInputStream sink) throws IOException 99: { 100: if (this.sink != null || sink.source != null) 101: throw new IOException ("Already connected"); 102: sink.connect(this); 103: } 104: 105: /** 106: * Write a single byte of date to the stream. Note that this method will 107: * block if the <code>PipedInputStream</code> to which this object is 108: * connected has a full buffer. 109: * 110: * @param b The byte of data to be written, passed as an <code>int</code>. 111: * 112: * @exception IOException If the stream has not been connected or has 113: * been closed. 114: */ 115: public void write(int b) throws IOException 116: { 117: if (sink == null) 118: throw new IOException ("Not connected"); 119: if (closed) 120: throw new IOException ("Pipe closed"); 121: 122: sink.receive (b); 123: } 124: 125: /** 126: * This method writes <code>len</code> bytes of data from the byte array 127: * <code>buf</code> starting at index <code>offset</code> in the array 128: * to the stream. Note that this method will block if the 129: * <code>PipedInputStream</code> to which this object is connected has 130: * a buffer that cannot hold all of the bytes to be written. 131: * 132: * @param buffer The array containing bytes to write to the stream. 133: * @param offset The index into the array to start writing bytes from. 134: * @param len The number of bytes to write. 135: * 136: * @exception IOException If the stream has not been connected or has 137: * been closed. 138: */ 139: public void write(byte[] buffer, int offset, int len) throws IOException 140: { 141: if (sink == null) 142: throw new IOException ("Not connected"); 143: if (closed) 144: throw new IOException ("Pipe closed"); 145: 146: sink.receive(buffer, offset, len); 147: } 148: 149: /** 150: * This method does nothing. 151: * 152: * @exception IOException If the stream is closed. 153: * @specnote You'd think that this method would block until the sink 154: * had read all available data. Thats not the case - this method 155: * appears to be a no-op? 156: */ 157: public void flush() throws IOException 158: { 159: } 160: 161: /** 162: * This method closes this stream so that no more data can be written 163: * to it. Any further attempts to write to this stream may throw an 164: * exception 165: * 166: * @exception IOException If an error occurs 167: */ 168: public void close() throws IOException 169: { 170: // A close call on an unconnected PipedOutputStream has no effect. 171: if (sink != null) 172: { 173: closed = true; 174: // Notify any waiting readers that the stream is now closed. 175: synchronized (sink) 176: { 177: sink.notifyAll(); 178: } 179: } 180: } 181: }