alvinalexander.com | career | drupal | java | mac | mysql | perl | scala | uml | unix  

ActiveMQ example source code file (AMQReader.java)

This example ActiveMQ source code file (AMQReader.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

amqreader, asyncdatamanager, illegalstateexception, illegalstateexception, invalidselectorexception, io, ioexception, ioexception, location, message, message, messagelocation, messagelocation, set, string, util

The ActiveMQ AMQReader.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.console.command.store.amq.reader;

import java.io.File;
import java.io.IOException;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;

import javax.jms.InvalidSelectorException;
import javax.jms.Message;

import org.apache.activemq.command.DataStructure;
import org.apache.activemq.filter.BooleanExpression;
import org.apache.activemq.kaha.impl.async.AsyncDataManager;
import org.apache.activemq.kaha.impl.async.Location;
import org.apache.activemq.openwire.OpenWireFormat;
import org.apache.activemq.selector.SelectorParser;
import org.apache.activemq.util.ByteSequence;
import org.apache.activemq.wireformat.WireFormat;

/**
 * Reads and iterates through data log files for the AMQMessage Store
 * 
 */
public class AMQReader implements Iterable<Message> {

    private AsyncDataManager dataManager;
    private WireFormat wireFormat = new OpenWireFormat();
    private File file;
    private BooleanExpression expression;

    /**
     * List all the data files in a directory
     * @param directory
     * @return
     * @throws IOException
     */
    public static Set<File> listDataFiles(File directory) throws IOException{
        Set<File>result = new HashSet();
        if (directory == null || !directory.exists() || !directory.isDirectory()) {
            throw new IOException("Invalid Directory " + directory);
        }
        AsyncDataManager dataManager = new AsyncDataManager();
        dataManager.setDirectory(directory);
        dataManager.start();
        Set<File> set = dataManager.getFiles();
        if (set != null) {
            result.addAll(set);
        }
        dataManager.close();
        return result;
    }
    /**
     * Create the AMQReader to read a directory of amq data logs - or an
     * individual data log file
     * 
     * @param file the directory - or file
     * @throws IOException 
     * @throws InvalidSelectorException 
     * @throws IOException
     * @throws InvalidSelectorException 
     */
    public AMQReader(File file) throws InvalidSelectorException, IOException {
        this(file,null);
    }
    
    /**
     * Create the AMQReader to read a directory of amq data logs - or an
     * individual data log file
     * 
     * @param file the directory - or file
     * @param selector the JMS selector or null to select all
     * @throws IOException
     * @throws InvalidSelectorException 
     */
    public AMQReader(File file, String selector) throws IOException, InvalidSelectorException {
        String str = selector != null ? selector.trim() : null;
        if (str != null && str.length() > 0) {
            this.expression=SelectorParser.parse(str);
        }
        dataManager = new AsyncDataManager();
        dataManager.setArchiveDataLogs(false);
        if (file.isDirectory()) {
            dataManager.setDirectory(file);
        } else {
            dataManager.setDirectory(file.getParentFile());
            dataManager.setDirectoryArchive(file);
            this.file = file;
        }
        dataManager.start();
    }

    public Iterator<Message> iterator() {
        return new AMQIterator(this,this.expression);
    }

    
    protected MessageLocation getNextMessage(MessageLocation lastLocation)
            throws IllegalStateException, IOException {
        if (this.file != null) {
            return getInternalNextMessage(this.file, lastLocation);
        }
        return getInternalNextMessage(lastLocation);
    }

    private MessageLocation getInternalNextMessage(MessageLocation lastLocation)
            throws IllegalStateException, IOException {
        return getInternalNextMessage(null, lastLocation);
    }

    private MessageLocation getInternalNextMessage(File file,
            MessageLocation lastLocation) throws IllegalStateException,
            IOException {
        MessageLocation result = lastLocation;
        if (result != null) {
            result.setMessage(null);
        }
        Message message = null;
        Location pos = lastLocation != null ? lastLocation.getLocation() : null;
        while ((pos = getNextLocation(file, pos)) != null) {
            message = getMessage(pos);
            if (message != null) {
                if (result == null) {
                    result = new MessageLocation();
                }
                result.setMessage(message);
                break;
            }
        }
        result.setLocation(pos);
        if (pos == null && message == null) {
            result = null;
        } else {
            result.setLocation(pos);
        }
        return result;
    }

    private Location getNextLocation(File file, Location last)
            throws IllegalStateException, IOException {
        if (file != null) {
            return dataManager.getNextLocation(file, last, true);
        }
        return dataManager.getNextLocation(last);
    }

    private Message getMessage(Location location) throws IOException {
        ByteSequence data = dataManager.read(location);
        DataStructure c = (DataStructure) wireFormat.unmarshal(data);
        if (c instanceof Message) {
            return (Message) c;
        }
        return null;

    }
}

Other ActiveMQ examples (source code examples)

Here is a short list of links related to this ActiveMQ AMQReader.java source code file:

... this post is sponsored by my books ...

#1 New Release!

FP Best Seller

 

new blog posts

 

Copyright 1998-2021 Alvin Alexander, alvinalexander.com
All Rights Reserved.

A percentage of advertising revenue from
pages under the /java/jwarehouse URI on this website is
paid back to open source projects.