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Java example source code file (BufferAllocator.java)

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

Learn more about this Java project at its project page.

Java - Java tags/keywords

bufferallocator, large_size_limit, medium_size_limit, small_size_limit

The BufferAllocator.java Java example source code

/*
 * Copyright (c) 2005, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package com.sun.xml.internal.stream.util;

import java.lang.ref.*;

/**
 * Buffer allocator for buffers of sizes 128 B, 2 KB and 8 KB. Includes
 * methods for allocating and freeing buffers.
 *
 * @author Binu.John@sun.com
 * @author Santiago.PericasGeertsen@sun.com
 */
public class BufferAllocator {
    public static int SMALL_SIZE_LIMIT = 128;
    public static int MEDIUM_SIZE_LIMIT = 2048;
    public static int LARGE_SIZE_LIMIT = 8192;

    char[] smallCharBuffer;
    char[] mediumCharBuffer;
    char[] largeCharBuffer;

    byte[] smallByteBuffer;
    byte[] mediumByteBuffer;
    byte[] largeByteBuffer;

    public BufferAllocator() {
    }

    public char[] getCharBuffer(int size) {
        if (size <= SMALL_SIZE_LIMIT) {
            char[] buffer = smallCharBuffer;
            smallCharBuffer = null;
            return buffer;
        }
        else if (size <= MEDIUM_SIZE_LIMIT) {
            char[] buffer = mediumCharBuffer;
            mediumCharBuffer = null;
            return buffer;
        }
        else if (size <= LARGE_SIZE_LIMIT) {
            char[] buffer = largeCharBuffer;
            largeCharBuffer = null;
            return buffer;
        }
        return null;
    }

    public void returnCharBuffer(char[] c) {
        if (c == null) {
            return;
        }
        if (c.length <= SMALL_SIZE_LIMIT) {
            smallCharBuffer = c;
        }
        else if (c.length <= MEDIUM_SIZE_LIMIT) {
            mediumCharBuffer = c;
        }
        else if (c.length <= LARGE_SIZE_LIMIT) {
            largeCharBuffer = c;
        }
    }

    public byte[] getByteBuffer(int size) {
        if (size <= SMALL_SIZE_LIMIT) {
            byte[] buffer = smallByteBuffer;
            smallByteBuffer = null;
            return buffer;
        }
        else if (size <= MEDIUM_SIZE_LIMIT) {
            byte[] buffer = mediumByteBuffer;
            mediumByteBuffer = null;
            return buffer;
        }
        else if (size <= LARGE_SIZE_LIMIT) {
            byte[] buffer = largeByteBuffer;
            largeByteBuffer = null;
            return buffer;
        }
        return null;
    }

    public void returnByteBuffer(byte[] b) {
        if (b == null) {
            return;
        }
        if (b.length <= SMALL_SIZE_LIMIT) {
            smallByteBuffer = b;
        }
        else if (b.length <= MEDIUM_SIZE_LIMIT) {
            mediumByteBuffer = b;
        }
        else if (b.length <= LARGE_SIZE_LIMIT) {
            largeByteBuffer = b;
        }
    }

}

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