ActiveMQ example source code file (SyncDataFileReader.java)

This example ActiveMQ source code file (SyncDataFileReader.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

databytearrayinputstream, databytearrayinputstream, datamanagerimpl, io, ioexception, ioexception, object, randomaccessfile, randomaccessfile, storelocation, syncdatafilereader, syncdatafilereader

The ActiveMQ SyncDataFileReader.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.kaha.impl.data;

import java.io.IOException;
import java.io.RandomAccessFile;
import org.apache.activemq.kaha.Marshaller;
import org.apache.activemq.kaha.StoreLocation;
import org.apache.activemq.util.DataByteArrayInputStream;

/**
 * Optimized Store reader
 * 
 * 
 */
public final class SyncDataFileReader {

    private DataManagerImpl dataManager;
    private DataByteArrayInputStream dataIn;

    /**
     * Construct a Store reader
     * 
     * @param fileId
     */
    SyncDataFileReader(DataManagerImpl fileManager) {
        this.dataManager = fileManager;
        this.dataIn = new DataByteArrayInputStream();
    }

    /*
     * (non-Javadoc)
     * 
     * @see org.apache.activemq.kaha.impl.data.DataFileReader#readDataItemSize(org.apache.activemq.kaha.impl.data.DataItem)
     */
    public synchronized byte readDataItemSize(DataItem item) throws IOException {
        RandomAccessFile file = dataManager.getDataFile(item).getRandomAccessFile();
        file.seek(item.getOffset()); // jump to the size field
        byte rc = file.readByte();
        item.setSize(file.readInt());
        return rc;
    }

    /*
     * (non-Javadoc)
     * 
     * @see org.apache.activemq.kaha.impl.data.DataFileReader#readItem(org.apache.activemq.kaha.Marshaller,
     *      org.apache.activemq.kaha.StoreLocation)
     */
    public synchronized Object readItem(Marshaller marshaller, StoreLocation item) throws IOException {
        RandomAccessFile file = dataManager.getDataFile(item).getRandomAccessFile();

        // TODO: we could reuse the buffer in dataIn if it's big enough to avoid
        // allocating byte[] arrays on every readItem.
        byte[] data = new byte[item.getSize()];
        file.seek(item.getOffset() + DataManagerImpl.ITEM_HEAD_SIZE);
        file.readFully(data);
        dataIn.restart(data);
        return marshaller.readPayload(dataIn);
    }
}