Netty-一个简单的服务器

内容：利用Netty实现的一个服务器和客户端交互，理解过程曲折心酸：传送门。

服务端：

public class EchoServer {
	private final int port;

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

	public void start() throws Exception {
		EventLoopGroup group = new NioEventLoopGroup();
		try {
			ServerBootstrap b = new ServerBootstrap();
			b.group(group)
				.channel(NioServerSocketChannel.class)
				.localAddress(port)
				.childHandler(new ChannelInitializer<Channel>() {

					@Override
					protected void initChannel(Channel arg0) throws Exception {
						arg0.pipeline().addLast(new EchoServerHandler());
					}
				});

			ChannelFuture f = b.bind().sync();
			System.out.println(EchoServer.class.getName() + "开始监听: " + f.channel().localAddress());
			f.channel().closeFuture().sync();
		} finally {
			group.shutdownGracefully().sync();
		}
	}

	public static void main(String[] args) throws Exception {
		new EchoServer(8080).start();
	}
}

public class EchoServerHandler extends ChannelHandlerAdapter {

	@Override
	public void channelRead(ChannelHandlerContext ctx, Object msg)
			throws Exception {
		ByteBuf buf = (ByteBuf) msg;
		byte[] req = new byte[buf.readableBytes()];
		buf.readBytes(req);
		String body = new String(req, "UTF-8");
		System.out.println("Server receive : " + body);
		String currentTime = new java.util.Date(System.currentTimeMillis()).toString();
		ByteBuf resp = Unpooled.copiedBuffer(currentTime.getBytes());
		ctx.write(resp);
	}

    @Override
    public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
    	ctx.flush();
    }

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

客户端：

public class EchoClient {
	private final String host;
	private final int port;

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

	public void start() throws Exception {
		EventLoopGroup group = new NioEventLoopGroup();
		try {
			Bootstrap b = new Bootstrap();
			b.group(group)
				.channel(NioSocketChannel.class)
				.remoteAddress(new InetSocketAddress(host, port))
				.handler(new ChannelInitializer<Channel>() {

					@Override
					protected void initChannel(Channel arg0) throws Exception {
						arg0.pipeline().addLast(new EchoClientHandler());
					}
				});

			ChannelFuture f = b.connect().sync();
			f.channel().closeFuture().sync();
		} finally {
			group.shutdownGracefully().sync();
		}
	}

	public static void main(String[] args) throws Exception {
		new EchoClient("localhost", 8080).start();
	}
}

public class EchoClientHandler extends ChannelHandlerAdapter {

	private static final Logger logger = Logger
			.getLogger(TimeClientHandler.class.getName());

	private final ByteBuf firstMessage;

	public EchoClientHandler() {
		byte[] req = "HELLO WORLD".getBytes();
		firstMessage = Unpooled.buffer(req.length);
		firstMessage.writeBytes(req);
	}

	@Override
	public void channelActive(ChannelHandlerContext ctx) {
		ctx.writeAndFlush(firstMessage);
	}

	@Override
	public void channelRead(ChannelHandlerContext ctx, Object msg)
			throws Exception {
		ByteBuf buf = (ByteBuf) msg;
		byte[] req = new byte[buf.readableBytes()];
		buf.readBytes(req);
		String body = new String(req, "UTF-8");
		System.out.println("Client Receive : " + body);
	}

	@Override
	public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
		// 释放资源
		logger.warning("Unexpected exception from downstream : "
				+ cause.getMessage());
		ctx.close();
	}

}