Netty echo server 简例

本例使用 String 编码解码器处理类

服务器端：

public class Server {

	private static final int port = 10086;

	public void startup() throws InterruptedException {
		EventLoopGroup bossGroup = new NioEventLoopGroup();
		EventLoopGroup workerGroup = new NioEventLoopGroup();
		try {
			ServerBootstrap b = new ServerBootstrap();
			b.group(bossGroup, workerGroup);
			b.channel(NioServerSocketChannel.class);
			b.childHandler(new ServerHandlerInitializer());

			// 绑定端口启动服务
			ChannelFuture f = b.bind(port).sync();
			// 监听服务器关闭
			f.channel().closeFuture().sync();
		} finally {
			bossGroup.shutdownGracefully();
			workerGroup.shutdownGracefully();
		}
	}

	public static void main(String[] args) throws InterruptedException {
		new Server().startup();
	}

}

ServerHandlerInitializer：

public class ServerHandlerInitializer extends ChannelInitializer {

	// ChannelPipeline 的执行顺序, 举例说明(官方文档)
	// p.addLast("1", new InboundHandlerA());
	// p.addLast("2", new InboundHandlerB());
	// p.addLast("3", new OutboundHandlerA());
	// p.addLast("4", new OutboundHandlerB());
	// p.addLast("5", new InboundOutboundHandlerX());
	// 如果是接收，执行顺序：1,2,5 (实现 ChannelInboundHandler 的处理类）
	// 如果是流出，执行顺序：5,4,3 (实现 ChannelOutboundHandler 的处理类)
	@Override
	protected void initChannel(SocketChannel ch) throws Exception {
		// 以("\n")为结尾分割的解码器
		ch.pipeline().addLast(new DelimiterBasedFrameDecoder(8192, Delimiters.lineDelimiter()));
		// 字符解码器
		ch.pipeline().addLast(new StringDecoder());
		// 字符编码器
		ch.pipeline().addLast(new StringEncoder());
		// 自定义
		ch.pipeline().addLast(new ServerHandler());
	}

}

ServerHandler：

public class ServerHandler extends SimpleChannelInboundHandler {

	// 接收到新数据时
	@Override
	protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {
		// 接收信息
		System.out.println(ctx.channel().remoteAddress() + " : " + msg);

		// 返回客户端消息, \n 是必须的, 客户端接受时也使用 DelimiterBasedFrameDecoder 判断结束位置
		ctx.writeAndFlush("Received your message !\n");
	}
	
	// 客户端连接时触发
	@Override
	public void channelActive(ChannelHandlerContext ctx) throws Exception {
		System.out.println("RamoteAddress : " + ctx.channel().remoteAddress() + " connected !");
		ctx.writeAndFlush( "Welcome!\n");
	}

}

客户端：

public class Client {

	private String host;
	private int port;

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

	public void connect() throws Exception {
		EventLoopGroup group = new NioEventLoopGroup();
		try {
			Bootstrap b = new Bootstrap();
			b.group(group);
			b.channel(NioSocketChannel.class);
			b.handler(new ClientHandlerInitializer());

			// 连接服务器
			Channel ch = b.connect(host, port).sync().channel();

			// 接受系统输入
			BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
			// 连续输入
			while (true) {
				String line = in.readLine();
				if (line == null) // 如果是空行, 则跳过本次循环, 不输出
					continue;
				ch.writeAndFlush(line + "\r\n");
			}
		} finally {
			group.shutdownGracefully();
		}
	}

	public static void main(String[] args) throws Exception {
		new Client("localhost", 10086).connect();
	}

}

ClientHandlerInitializer：

public class ClientHandlerInitializer extends ChannelInitializer {

	@Override
	protected void initChannel(SocketChannel ch) throws Exception {
		// 编码解码需和服务器端对应
		ch.pipeline().addLast(new DelimiterBasedFrameDecoder(8192, Delimiters.lineDelimiter()));
		ch.pipeline().addLast(new StringDecoder());
		ch.pipeline().addLast(new StringEncoder());
		ch.pipeline().addLast(new ClientHandler());
	}

}

ClientHandler：

public class ClientHandler extends SimpleChannelInboundHandler {

	// 处理服务器响应
	@Override
	protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {
		System.out.println("Server : " + msg);
	}

}