001 /** 002 * 003 * Copyright 2004 Protique Ltd 004 * 005 * Licensed under the Apache License, Version 2.0 (the "License"); 006 * you may not use this file except in compliance with the License. 007 * You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 * 017 **/ 018 019 package org.activemq.streams; 020 import java.io.EOFException; 021 import java.io.IOException; 022 import java.io.OutputStream; 023 import javax.jms.BytesMessage; 024 import javax.jms.JMSException; 025 import javax.jms.MessageProducer; 026 import org.activemq.message.ActiveMQBytesMessage; 027 028 /** 029 * OutputStream that writes on to JMS via the supplied JMS MessageProducer 030 * 031 * @version $Revision: 1.1.1.1 $ 032 */ 033 public class JMSOutputStream extends OutputStream { 034 private final static int BUFFER_SIZE = 16 * 1024; 035 private byte[] buf; 036 private int count; 037 private boolean closed; 038 private MessageProducer producer; 039 040 041 /** 042 * Creates a new output stream to write data using the supplied JMS MessageProducer 043 * @param producer 044 */ 045 public JMSOutputStream(MessageProducer producer) { 046 this(producer,BUFFER_SIZE); 047 } 048 049 /** 050 * Creates a new output stream to write data using the supplied JMS MessageProducer 051 * @param producer 052 * @param size the buffer size. 053 * @throws IllegalArgumentException if size <= 0. 054 */ 055 public JMSOutputStream(MessageProducer producer, int size) { 056 if (size <= 0) { 057 throw new IllegalArgumentException("Buffer size <= 0"); 058 } 059 buf = new byte[size]; 060 this.producer = producer; 061 } 062 063 /** 064 * write a byte on to the stream 065 * 066 * @param b - byte to write 067 * @throws IOException 068 */ 069 public void write(int b) throws IOException { 070 checkClosed(); 071 if (availableBufferToWrite() < 1) { 072 flush(); 073 } 074 buf[count++] = (byte) b; 075 } 076 077 078 /** 079 * write a byte array to the stream 080 * 081 * @param b the byte buffer 082 * @param off the offset into the buffer 083 * @param len the length of data to write 084 * @throws IOException 085 */ 086 public void write(byte b[], int off, int len) throws IOException { 087 checkClosed(); 088 if (availableBufferToWrite() < len) { 089 flush(); 090 } 091 if (buf.length >= len) { 092 System.arraycopy(b, off, buf, count, len); 093 count += len; 094 } 095 else { 096 writeBuffer(b, off, len); 097 } 098 } 099 100 /** 101 * flush the data to the output stream 102 * This doesn't call flush on the underlying outputstream, because 103 * Tcp is particularly efficent at doing this itself .... 104 * 105 * @throws IOException 106 */ 107 public void flush() throws IOException { 108 checkClosed(); 109 if (count > 0 ) { 110 writeBuffer(buf, 0, count); 111 count = 0; 112 } 113 } 114 115 /** 116 * close this stream 117 * 118 * @throws IOException 119 */ 120 public void close() throws IOException { 121 if (!closed) { 122 write(-1); 123 flush(); 124 super.close(); 125 closed = true; 126 try { 127 producer.close(); 128 } 129 catch (JMSException jmsEx) { 130 IOException ioEx = new IOException(jmsEx.getMessage()); 131 throw ioEx; 132 } 133 } 134 } 135 136 137 /** 138 * Checks that the stream has not been closed 139 * 140 * @throws IOException 141 */ 142 protected void checkClosed() throws IOException { 143 if (closed) { 144 throw new EOFException("Cannot write to the stream any more it has already been closed"); 145 } 146 } 147 148 /** 149 * @return the amount free space in the buffer 150 */ 151 private int availableBufferToWrite() { 152 return buf.length - count; 153 } 154 155 private void writeBuffer(byte[] buf,int offset, int length) throws IOException{ 156 try { 157 BytesMessage message = new ActiveMQBytesMessage(); 158 message.writeBytes(buf,offset,length); 159 producer.send(message); 160 }catch(JMSException jmsEx){ 161 IOException ioEx = new IOException(jmsEx.getMessage()); 162 throw ioEx; 163 } 164 } 165 }