Netty EchoServer 和 EchoClient 实现

EchoServer.java

public class EchoServer {

  private final int port;

  public EchoServer(int port) {
    this.port = port;
  }

  public static void main(String[] args) throws Exception {
    if (args.length != 1) {
      System.err.println("Usage: " + EchoServer.class.getSimpleName() + " ");
      System.exit(1);
    }
    int port = 8080;
    try {
      port = Integer.parseInt(args[0]);
    } catch (Exception e) {
      System.out.println("传入端口不是数字，采用默认端口: " + port);
    }

    new EchoServer(port).start();
  }

  public void start() throws Exception {
    final EchoServerHandler handler = new EchoServerHandler();
    EventLoopGroup group = new NioEventLoopGroup();

    try {
      ServerBootstrap bootstrap = new ServerBootstrap();
      bootstrap.group(group)
        .channel(NioServerSocketChannel.class)
        .localAddress(new InetSocketAddress(port))
        .childHandler(new ChannelInitializer<SocketChannel>() {
          protected void initChannel(SocketChannel socketChannel) throws Exception {
            socketChannel.pipeline().addLast(handler);
          }
        });
      ChannelFuture future = bootstrap.bind().sync();
      future.channel().closeFuture().sync();
    }finally {
      group.shutdownGracefully().sync();
    }

  }
}

EchoServerHandler.java

@Sharable
public class EchoServerHandler extends ChannelInboundHandlerAdapter {

  @Override
  public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
    ByteBuf in = (ByteBuf) msg;
    System.out.println("Server Received: " + in.toString(CharsetUtil.UTF_8));
    ctx.write(in);
  }

  @Override
  public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
    ctx.writeAndFlush(Unpooled.EMPTY_BUFFER).addListener(ChannelFutureListener.CLOSE);
  }

  @Override
  public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
    cause.printStackTrace();
    ctx.close();
  }
}

EchoClient.java

public class EchoClient {

  private final String host;
  private final int port;

  public EchoClient(String host, int port) {
    this.host = host;
    this.port = port;
  }

  public static void main(String[] args) throws Exception {
    if (args.length != 2) {
      System.out.println("Usage: " + EchoClient.class.getSimpleName() + "  ");
      System.exit(1);
    }
    String host = args[0];
    int port = Integer.parseInt(args[1]);
    new EchoClient(host, port).start();
  }

  public void start() throws Exception {
    EventLoopGroup group = new NioEventLoopGroup();
    try {
      Bootstrap bootstrap = new Bootstrap();
      bootstrap.group(group)
        .channel(NioSocketChannel.class)
        .remoteAddress(new InetSocketAddress(host, port))
        .handler(new ChannelInitializer<SocketChannel>() {
          protected void initChannel(SocketChannel socketChannel) throws Exception {
            socketChannel.pipeline().addLast(new EchoClientHandler());
          }
        });
      ChannelFuture future = bootstrap.connect().sync();
      future.channel().closeFuture().sync();
    } finally {
      group.shutdownGracefully().sync();
    }
  }
}

EchoClientHandler.java

@Sharable
public class EchoClientHandler extends SimpleChannelInboundHandler<ByteBuf> {

  @Override
  public void channelActive(ChannelHandlerContext ctx) throws Exception {
    ctx.writeAndFlush(Unpooled.copiedBuffer("Netty Rocks!", CharsetUtil.UTF_8));
  }

  protected void channelRead0(ChannelHandlerContext channelHandlerContext, ByteBuf byteBuf)
    throws Exception {
    System.out.println("Client Received: " + byteBuf.toString(CharsetUtil.UTF_8));
  }

  @Override
  public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
    cause.printStackTrace();
    ctx.close();
  }

}