netty-netty基本使用

netty-netty基本使用

摘自<netty权威r指南>

编写netty服务器和客户端三部曲:

• 绑定Group(EventLoopGroup,即一组EventLoop集合，可以理解成socket线程组)
• 声明Channel
• 指定ChannelHandler

服务器端

public class TimeServerHandler extends ChannelInboundHandlerAdapter {


	@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("time server recv[x]: "+ body);

		String currentTime = "time".equals(body) ?
             new Date(System.currentTimeMillis()).toString() : "bad time";
		ByteBuf resp = Unpooled.copiedBuffer(currentTime.getBytes());
		ctx.write(resp);
	}

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

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

服务器启动类:

public class TimeServer {

	public static void main(String[] args) {
		int port = 8080;
		new TimeServer().bind(port);
	}

	public void bind(int port) {
		EventLoopGroup bossGroup = new NioEventLoopGroup();
		EventLoopGroup workGroup = new NioEventLoopGroup();
		try {

			ServerBootstrap serverBootstrap = new ServerBootstrap();
			serverBootstrap.group(bossGroup, workGroup)
					.channel(NioServerSocketChannel.class)
					.option(ChannelOption.SO_BACKLOG, 1024)
					.childHandler(new ChildChannelHandler());
			//阻塞到启动成功
//			ChannelFuture future = serverBootstrap.bind(port).sync();
			ChannelFuture future = serverBootstrap.bind(port);
			future.addListener(new ChannelFutureListener() {
				@Override
				public void operationComplete(ChannelFuture future)
                                                         throws Exception {
					if (future.isSuccess()){
						System.out.println("server started success...");
					}else {
						System.out.println("server started failed...");
						future.cause().printStackTrace();
					}
				}
			});
			future.channel().closeFuture().sync();
		} catch (InterruptedException e) {
			e.printStackTrace();
		} finally {
			bossGroup.shutdownGracefully();
			workGroup.shutdownGracefully();
		}
	}

}

客户端

public class TimeClientHandler extends ChannelInboundHandlerAdapter {

	private final ByteBuf firstMsg;

	public TimeClientHandler() {
		String time = "time";
		firstMsg = Unpooled.copiedBuffer(time.getBytes());
	}

	@Override
	public void channelActive(ChannelHandlerContext ctx) throws Exception {
		ctx.writeAndFlush(firstMsg);
	}

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

	}

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

客户端启动类:

public class TimeClient {

	public static void main(String[] args) throws InterruptedException {
		int port = 8080;
		String host = "127.0.0.1";
		new TimeClient().connect(port, host);
	}
	public void connect(int port, String host) throws InterruptedException {
		EventLoopGroup group = new NioEventLoopGroup();
		try {
			Bootstrap bootstrap = new Bootstrap();
			bootstrap.group(group).channel(NioSocketChannel.class)
					.option(ChannelOption.TCP_NODELAY,true)
					.handler(new ChannelInitializer<SocketChannel>() {
						@Override
						protected void initChannel(SocketChannel ch) 
															throws Exception {
							ch.pipeline().addLast(new TimeClientHandler());
						}
					});
			//阻塞到连接成功
//			ChannelFuture future= bootstrap.connect(host, port).sync();
			ChannelFuture future= bootstrap.connect(host, port);
			future.addListener(new ChannelFutureListener() {
				@Override
				public void operationComplete(ChannelFuture future) 
														throws Exception {
					if (future.isSuccess()){
						System.out.println("client established success...");
					}else {
						System.out.println("client established failed...");
						future.cause().printStackTrace();
					}
				}
			});
			future.channel().closeFuture().sync();
		} finally {
			group.shutdownGracefully();

		}
	}
}

运行结果

1.服务器端运行结果:

server started success...
time server recv[x]: time

2.客户端运行结果:

client established success...
now is :Mon Feb 03 15:51:51 CST 2020