问在Java中使用AsynchronousSocketChannel

EN

public class EchoClient {

    public AsynchronousSocketChannel sockChannel;

    public EchoClient(String host, int port) throws IOException {
        sockChannel = AsynchronousSocketChannel.open();

        sockChannel.connect( new InetSocketAddress(host, port), sockChannel, new CompletionHandler<Void, AsynchronousSocketChannel >() {
            @Override
            public void completed(Void result, AsynchronousSocketChannel channel ) {
                System.out.println( "success");
            }

            @Override
            public void failed(Throwable exc, AsynchronousSocketChannel channel) {
                System.out.println( "failed to connect to server");
            }

        });
    }

    public void startRead() {
        final ByteBuffer buf = ByteBuffer.allocate(2048);

        sockChannel.read( buf, sockChannel, new CompletionHandler<Integer, AsynchronousSocketChannel>(){

            @Override
            public void completed(Integer result, AsynchronousSocketChannel channel) {
                //print the message
                System.out.println( "Read message:" + new String( buf.array()) );
            }

            @Override
            public void failed(Throwable exc, AsynchronousSocketChannel channel) {
            }

        });

    }

    public void write(final String message) {
        ByteBuffer buf = ByteBuffer.allocate(2048);
        buf.put(message.getBytes());
        buf.flip();
        sockChannel.write(buf, sockChannel, new CompletionHandler<Integer, AsynchronousSocketChannel >() {
            @Override
            public void completed(Integer result, AsynchronousSocketChannel channel ) {

            }

            @Override
            public void failed(Throwable exc, AsynchronousSocketChannel channel) {
                System.out.println( "Fail to write the message to server");
            }
        });
    }

}

EchoClient echo = new EchoClient( "127.0.0.1", 3000, "echo test");
echo.startRead();
echo.write("hi");