AsyncNIOServer.java

package test;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.StandardSocketOptions;
import java.nio.ByteBuffer;
import java.nio.channels.AsynchronousServerSocketChannel;
import java.nio.channels.AsynchronousSocketChannel;
import java.nio.channels.CompletionHandler;

public class AsyncNIOServer {

	public static void main(String[] args) {

		try (final AsynchronousServerSocketChannel listener = 
				AsynchronousServerSocketChannel.open()) { 
			
		    listener.setOption(StandardSocketOptions.SO_REUSEADDR, true);
			listener.bind(new InetSocketAddress("localhost", 8080));
			
			while (true) {
				
				// callback 1
				listener.accept(null, new CompletionHandler<AsynchronousSocketChannel, Void>() {
					@Override
					public void completed(AsynchronousSocketChannel connection, Void v) {							
							listener.accept(null, this); // get ready for next connection				
							final ByteBuffer buffer = ByteBuffer.allocateDirect(1024);
							
							// callback 2
							connection.read(buffer, connection, new CompletionHandler<Integer, AsynchronousSocketChannel>() {
								@Override
								public void completed(Integer result, final AsynchronousSocketChannel scAttachment) {	
									if (result == -1) {
										try {
											scAttachment.close();
										} catch (IOException e) {
											e.printStackTrace();
										}
								    }
									
									// callback 3
									scAttachment.write((ByteBuffer) buffer.flip(), buffer, new CompletionHandler<Integer, ByteBuffer>() {		
										@Override
										public void completed(Integer result, ByteBuffer bbAttachment) {
											if (bbAttachment.hasRemaining()) {
												scAttachment.write(bbAttachment, bbAttachment, this);
											} else {
												bbAttachment.clear();
											}
										}		
										@Override
										public void failed(Throwable t, ByteBuffer bbAttachment) {
											t.printStackTrace();
										}										
									});	
									
								}
								@Override
								public void failed(Throwable t, AsynchronousSocketChannel scAttachment) {
									t.printStackTrace();
								}								
							});	
							
					}
					@Override
					public void failed(Throwable t, Void v) {
						t.printStackTrace();
					}					
				});

				System.in.read(); // so we don't exit before a connection is established
				
			}
			
		} catch (IOException e) {
			e.printStackTrace();
		} 

	}

}