Copies input Stream to output Stream via Channel. - Java java.nio.channels

Java examples for java.nio.channels:ReadableByteChannel

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Description

Copies input Stream to output Stream via Channel.

Demo Code


import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.nio.ByteBuffer;
import java.nio.channels.Channels;
import java.nio.channels.ReadableByteChannel;
import java.nio.channels.WritableByteChannel;

public class Main{
    /**/*www .  j  av  a 2 s  . co  m*/
     * Copies input to output. Closes both streams a the end!
     * 
     * @param input
     * @param output
     * @throws IOException
     */
    public static void fastStreamCopy(final InputStream input,
            final OutputStream output) throws IOException {
        ReadableByteChannel inputChannel = null;
        WritableByteChannel outputChannel = null;

        try {
            // get an channel from the stream
            inputChannel = Channels.newChannel(input);
            outputChannel = Channels.newChannel(output);
            // copy the channels
            ChannelUtil.fastChannelCopy(inputChannel, outputChannel);
        } finally {
            // closing the channels
            if (inputChannel != null) {
                inputChannel.close();
            }

            if (outputChannel != null) {
                outputChannel.close();
            }
        }
    }
    /**
     * Copies src to dst
     * 
     * @param src
     * @param dest
     * @throws IOException
     */
    public static void fastChannelCopy(final ReadableByteChannel src,
            final WritableByteChannel dest) throws IOException {
        final ByteBuffer buffer = ByteBuffer.allocateDirect(16 * 1024);
        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 doing clear()
            buffer.compact();
        }
        // EOF will leave buffer in fill state
        buffer.flip();
        // make sure the buffer is fully drained.
        while (buffer.hasRemaining()) {
            dest.write(buffer);
        }
    }
}

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