Java ReadableByteChannel Copy fastChannelCopy(final ReadableByteChannel src, final WritableByteChannel dest)

Description

Copies a ReadableByteChannel into a WritableByteChannel byte channel.

License

Apache License

Parameter

Parameter	Description
src	the <code>ReadableByteChannel</code> to read from
dest	the <code>ReadableByteChannel</code> to write into

Exception

Parameter	Description

Declaration

private static void fastChannelCopy(final ReadableByteChannel src, final WritableByteChannel dest) 

Method Source Code

//package com.java2s;
/*//from  w  w w .j  ava  2 s.c o m
 * Copyright (C) 2010 Google Code.
 *
 * Licensed 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.
 */

import java.io.IOException;

import java.nio.ByteBuffer;

import java.nio.channels.ReadableByteChannel;
import java.nio.channels.WritableByteChannel;

public class Main {
    /**
    * The default buffer size to use for 
    * {@link #copyLarge(InputStream, OutputStream)}
    * and
    * {@link #copyLarge(Reader, Writer)}
    */
    private static final int DEFAULT_BUFFER_SIZE = 1024 * 4;

    /**
     * Copies a <code>ReadableByteChannel</code> into a <code>WritableByteChannel</code> byte channel. Uses a <code>ByteBuffer</code>
     * to write to the channel. The buffer is drained before each write.
     * 
     * @param src the <code>ReadableByteChannel</code> to read from
     * @param dest the <code>ReadableByteChannel</code> to write into
     * @throws <code>IOException</code> if there is an I/O error
     */
    private static void fastChannelCopy(final ReadableByteChannel src, final WritableByteChannel dest) {
        final ByteBuffer buffer = ByteBuffer.allocateDirect(DEFAULT_BUFFER_SIZE);
        try {
            while (src.read(buffer) != -1) {
                //prepare the buffer to be drained.
                buffer.flip();
                //write to the channel. may block.
                dest.write(buffer);
                //if partial transfer, shift remainder down.
                //if buffer is empty, same as compact
                buffer.compact();
            }
            //EOF will leave buffer in fill state
            buffer.flip();

            //make sure buffer is fully drained.
            while (buffer.hasRemaining()) {
                dest.write(buffer);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

Related

1. copy(ReadableByteChannel source, WritableByteChannel destination)
2. copy(ReadableByteChannel src, WritableByteChannel dest)
3. copyTo(ReadableByteChannel from, WritableByteChannel to)
4. fastChannelCopy(final ReadableByteChannel input, final WritableByteChannel output, long toRead)
5. fastChannelCopy(final ReadableByteChannel src, final WritableByteChannel dest)
6. fastChannelCopy(ReadableByteChannel src, WritableByteChannel dest)
7. fastCopy(final ReadableByteChannel src, final WritableByteChannel dest)