IO channel间互相“流”数据的方案，尽可能zero-cory

IOUtil.java

package com.awilmore.ioutils;

import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.channels.ReadableByteChannel;
import java.nio.channels.SeekableByteChannel;
import java.nio.channels.WritableByteChannel;

public class IOUtil {

    private static final ByteBuffer buffer = ByteBuffer.allocateDirect(16 * 1024);

    public static void flow(final ReadableByteChannel src, final WritableByteChannel dest)
                                                                                          throws IOException {
        if (src instanceof FileChannel) {
            // transferTo
            FileChannel fc = (FileChannel) src;
            fc.transferTo(0, fc.size(), dest);
        } else if (dest instanceof FileChannel && src instanceof SeekableByteChannel) {
            // transferFrom
            FileChannel fc = (FileChannel) dest;
            fc.transferFrom(src, 0, ((SeekableByteChannel) src).size());
        } else {
            while (src.read(buffer) != -1) {
                buffer.flip();
                dest.write(buffer);
                buffer.compact();
            }
            buffer.flip();
            while (buffer.hasRemaining())
                dest.write(buffer);
        }
    }
}