Netty的入门-基础编程

Server端实现：

public class TimeServer {

	
	public void bind(int port) throws Exception {
		// 配置服务端的NIO线程组
		EventLoopGroup bossGroup = new NioEventLoopGroup(); // 用于服务端接受客户端的连接
		EventLoopGroup workerGroup = new NioEventLoopGroup(); // 用于进行SocketChannel的网络读写
		try {
			// 服务端启动辅助类
			ServerBootstrap b = new ServerBootstrap();
			b.group(bossGroup, workerGroup) // 两个NIO线程组
				.channel(NioServerSocketChannel.class) // 设置要创建的Channel
				.option(ChannelOption.SO_BACKLOG, 1024) // 设置TCP参数
				.childOption(ChannelOption.SO_KEEPALIVE, true) // 保持心跳
				.childHandler(new ChannelInitializer() {
					@Override
					protected void initChannel(SocketChannel socketChannel) throws Exception {
						socketChannel.pipeline().addLast(new TimeServerHandler());
					}
				}); // 绑定I/O事件的处理类，用于处理请求
			// 绑定端口，同步等待成功
			ChannelFuture f = b.bind(port).sync(); // 只要用于异步操作的通知回调
			// 等待服务端监听端口关闭
			f.channel().closeFuture().sync(); // 等待服务端链路关闭之后退出
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			// 优雅退出
			bossGroup.shutdownGracefully();
			workerGroup.shutdownGracefully();
		}
	}
	
	private class TimeServerHandler extends ChannelInboundHandlerAdapter  {

		@Override
		public void channelRead(ChannelHandlerContext ctx, Object msg)
				throws Exception {
			try {
				ByteBuf buf = (ByteBuf) msg;
				byte[] req = new byte[buf.readableBytes()];
				buf.readBytes(req);
				String body = new String(req, "UTF-8");
				System.out.println("The time server receive order ： " + body);
				String currentTime = "QUERY TIME ORDER".equals(body) ? new Date(System.currentTimeMillis()).toString() : "Bad Order";
				ByteBuf resp = Unpooled.copiedBuffer(currentTime.getBytes());
				ctx.write(resp); // 写到消息队列而不是写到SocketChannel中
			} finally {
				ReferenceCountUtil.release(msg);			
			}
		}

		@Override
		public void channelReadComplete(ChannelHandlerContext ctx)
				throws Exception {
			// 将消息发送队列中的消息写入到SocketChannel中发送给对方
			// 从性能角度考虑，为了防止频繁的唤醒selector进行消息发送
			ctx.flush();
		}

		@Override
		public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause)
				throws Exception {
			ctx.close();
		}
		
	}
	
	public static void main(String[] args) {
		try {
			new TimeServer().bind(1234);
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

}

客户端实现：

public class TimeClient {
	
	public void connect(int port, String host) {
		// 配置客户端NIO线程组
		EventLoopGroup group = new NioEventLoopGroup();
		try {
			Bootstrap b = new Bootstrap();
			b.group(group)
				.channel(NioSocketChannel.class)
				.handler(new ChannelInitializer() {

					@Override
					protected void initChannel(SocketChannel ch)
							throws Exception {
						ch.pipeline().addLast(new TimeClientHandler());
					}
				});
			// 发起异步连接操作
			ChannelFuture f = b.connect(host, port).sync();
			f.channel().closeFuture().sync();
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			// 优雅退出，释放NIO线程组
			group.shutdownGracefully();
		}
	}
	
	public class TimeClientHandler extends ChannelInboundHandlerAdapter  {
		private final ByteBuf firstMessage;
		
		public TimeClientHandler() {
			super();
			byte[] req = "QUERY TIME ORDER".getBytes();
			firstMessage = Unpooled.buffer(req.length);
			firstMessage.writeBytes(req);
		}

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

		@Override
		public void channelActive(ChannelHandlerContext ctx) throws Exception {
			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("Now is " + body);
		}
		
	}

	public static void main(String[] args) {
		new TimeClient().connect(1234, "127.0.0.1");
	}

}