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ActiveMQ example source code file (StompNIOTransport.java)

This example ActiveMQ source code file (StompNIOTransport.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - ActiveMQ tags/keywords

bytearrayoutputstream, dataoutputstream, exception, exception, io, ioexception, ioexception, net, network, nio, niooutputstream, stompframe, stompniotransport, stompniotransport, string, string, throwable, uri, util

The ActiveMQ StompNIOTransport.java source code

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.activemq.transport.stomp;

import java.io.ByteArrayInputStream;
import java.io.DataOutputStream;
import java.io.EOFException;
import java.io.IOException;
import java.net.Socket;
import java.net.URI;
import java.net.UnknownHostException;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.SocketChannel;
import java.util.HashMap;

import javax.net.SocketFactory;

import org.apache.activemq.command.Command;
import org.apache.activemq.transport.Transport;
import org.apache.activemq.transport.nio.NIOOutputStream;
import org.apache.activemq.transport.nio.SelectorManager;
import org.apache.activemq.transport.nio.SelectorSelection;
import org.apache.activemq.transport.tcp.TcpTransport;
import org.apache.activemq.util.ByteArrayOutputStream;
import org.apache.activemq.util.ByteSequence;
import org.apache.activemq.util.DataByteArrayInputStream;
import org.apache.activemq.util.IOExceptionSupport;
import org.apache.activemq.util.ServiceStopper;
import org.apache.activemq.wireformat.WireFormat;

/**
 * An implementation of the {@link Transport} interface for using Stomp over NIO
 *
 * 
 */
public class StompNIOTransport extends TcpTransport {

    private SocketChannel channel;
    private SelectorSelection selection;

    private ByteBuffer inputBuffer;
    ByteArrayOutputStream currentCommand = new ByteArrayOutputStream();
    boolean processedHeaders = false;
    String action;
    HashMap<String, String> headers;
    int contentLength = -1;
    int readLength = 0;
    int previousByte = -1;

    public StompNIOTransport(WireFormat wireFormat, SocketFactory socketFactory, URI remoteLocation, URI localLocation) throws UnknownHostException, IOException {
        super(wireFormat, socketFactory, remoteLocation, localLocation);
    }

    public StompNIOTransport(WireFormat wireFormat, Socket socket) throws IOException {
        super(wireFormat, socket);
    }

    protected void initializeStreams() throws IOException {
        channel = socket.getChannel();
        channel.configureBlocking(false);

        // listen for events telling us when the socket is readable.
        selection = SelectorManager.getInstance().register(channel, new SelectorManager.Listener() {
            public void onSelect(SelectorSelection selection) {
                serviceRead();
            }

            public void onError(SelectorSelection selection, Throwable error) {
                if (error instanceof IOException) {
                    onException((IOException)error);
                } else {
                    onException(IOExceptionSupport.create(error));
                }
            }
        });

        inputBuffer = ByteBuffer.allocate(8 * 1024);
        NIOOutputStream outPutStream = new NIOOutputStream(channel, 8 * 1024);
        this.dataOut = new DataOutputStream(outPutStream);
        this.buffOut = outPutStream;
    }

    private void serviceRead() {
        try {

           while (true) {
               // read channel
               int readSize = channel.read(inputBuffer);
               // channel is closed, cleanup
               if (readSize == -1) {
                   onException(new EOFException());
                   selection.close();
                   break;
               }
               // nothing more to read, break
               if (readSize == 0) {
                   break;
               }

               inputBuffer.flip();

               int b;
               ByteArrayInputStream input = new ByteArrayInputStream(inputBuffer.array());

               int i = 0;
               while(i++ < readSize) {
                   b = input.read();
                   // skip repeating nulls
                   if (!processedHeaders && previousByte == 0 && b == 0) {
                       continue;
                   }

                   if (!processedHeaders) {
                       currentCommand.write(b);
                       // end of headers section, parse action and header
                       if (previousByte == '\n' && b == '\n') {
                           if (wireFormat instanceof StompWireFormat) {
                               DataByteArrayInputStream data = new DataByteArrayInputStream(currentCommand.toByteArray());
                               action = ((StompWireFormat)wireFormat).parseAction(data);
                               headers = ((StompWireFormat)wireFormat).parseHeaders(data);
                               String contentLengthHeader = headers.get(Stomp.Headers.CONTENT_LENGTH);
                               if (contentLengthHeader != null) {
                                   contentLength = ((StompWireFormat)wireFormat).parseContentLength(contentLengthHeader);
                               } else {
                                   contentLength = -1;
                               }
                           }
                           processedHeaders = true;
                           currentCommand.reset();
                       }
                   } else {

                       if (contentLength == -1) {
                           // end of command reached, unmarshal
                           if (b == 0) {
                               processCommand();
                           } else {
                               currentCommand.write(b);
                           }
                       } else {
                           // read desired content length
                           if (readLength++ == contentLength) {
                               processCommand();
                               readLength = 0;
                           } else {
                               currentCommand.write(b);
                           }
                       }
                   }

                   previousByte = b;
               }
               // clear the buffer
               inputBuffer.clear();

           }
        } catch (IOException e) {
            onException(e);
        } catch (Throwable e) {
            onException(IOExceptionSupport.create(e));
        }
    }

    private void processCommand() throws Exception {
        StompFrame frame = new StompFrame(action, headers, currentCommand.toByteArray());
        doConsume(frame);
        processedHeaders = false;
        currentCommand.reset();
        contentLength = -1;
    }

    protected void doStart() throws Exception {
        connect();
        selection.setInterestOps(SelectionKey.OP_READ);
        selection.enable();
    }

    protected void doStop(ServiceStopper stopper) throws Exception {
        try {
            selection.close();
        } catch (Exception e) {
        	e.printStackTrace();
        }
        super.doStop(stopper);
    }
}

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