Netty学习之三—— Netty 实现 NIO操作

系统管理员 2022-02-21 07:36 280阅读 0赞

pom

<dependency>
    			<groupId>io.netty</groupId>
    			<artifactId>netty-all</artifactId>
    			<version>5.0.0.Alpha2</version>
    		</dependency>

服务端代码：

package com.netty.netty;
    
    import io.netty.bootstrap.ServerBootstrap;
    import io.netty.channel.ChannelFuture;
    import io.netty.channel.ChannelInitializer;
    import io.netty.channel.ChannelOption;
    import io.netty.channel.EventLoopGroup;
    import io.netty.channel.nio.NioEventLoopGroup;
    import io.netty.channel.socket.SocketChannel;
    import io.netty.channel.socket.nio.NioServerSocketChannel;
    
    public class NettyTimeServer {
        public void bind(int port) throws Exception {
            // 配置服务端的 NIO 线程组
            EventLoopGroup bossGroup = new NioEventLoopGroup();
            EventLoopGroup workerGroup = new NioEventLoopGroup();
            try {
                ServerBootstrap b = new ServerBootstrap();
                b.group(bossGroup, workerGroup)
                        .channel(NioServerSocketChannel.class)
                        .option(ChannelOption.SO_BACKLOG, 1024)
                        .childHandler(new ChildChannelHandler());
                // 绑定端口，同步等待成功
                ChannelFuture f = b.bind(port).sync();
    
                // 等待服务端监听端口关闭
                f.channel().closeFuture().sync();
            } finally {
                bossGroup.shutdownGracefully();
                workerGroup.shutdownGracefully();
            }
        }
    
        private class ChildChannelHandler extends ChannelInitializer<SocketChannel> {
    
            @Override
            protected void initChannel(SocketChannel socketChannel) throws Exception {
                socketChannel.pipeline().addLast(new NettyTimeServerHandler());
            }
        }
    
        public static void main(String[] args) throws Exception {
            int port = 8080;
            new NettyTimeServer().bind(port);
        }
    }

package com.netty.netty;
    
    
    import io.netty.buffer.ByteBuf;
    import io.netty.buffer.Unpooled;
    import io.netty.channel.ChannelHandlerAdapter;
    import io.netty.channel.ChannelHandlerContext;
    
    import java.util.Date;
    
    public class NettyTimeServerHandler extends ChannelHandlerAdapter {
        @Override
        public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
            ctx.close();
        }
    
        @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 recv body: " + body);
            String now = "QUERY TIME ORDER".equals(body) ? new Date(System.currentTimeMillis()).toString()
                    : "BAD ORDER";
            ByteBuf resp = Unpooled.copiedBuffer(now.getBytes());
            ctx.write(resp);
        }
    
        @Override
        public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
            ctx.flush();
        }
    }

客户端代码：

package com.netty.netty;
    
    import io.netty.bootstrap.Bootstrap;
    import io.netty.channel.ChannelFuture;
    import io.netty.channel.ChannelInitializer;
    import io.netty.channel.ChannelOption;
    import io.netty.channel.EventLoopGroup;
    import io.netty.channel.nio.NioEventLoopGroup;
    import io.netty.channel.socket.SocketChannel;
    import io.netty.channel.socket.nio.NioSocketChannel;
    
    public class NettyTimeClient {
        public void connect(int port, String host) throws Exception {
            EventLoopGroup group = new NioEventLoopGroup();
            try{
                Bootstrap b = new Bootstrap();
                b.group(group).channel(NioSocketChannel.class)
                        .option(ChannelOption.TCP_NODELAY, true)
                        .handler(new ChannelInitializer<SocketChannel>() {
                            @Override
                            protected void initChannel(SocketChannel socketChannel) throws Exception {
                                socketChannel.pipeline().addLast(new NettyTimeClientHandler());
                            }
                        });
                // 发起异步连接操作
                ChannelFuture f = b.connect(host, port).sync();
    
                // 等待客户端链路关闭
                f.channel().closeFuture().sync();
            } finally {
                group.shutdownGracefully();
            }
        }
    
        public static void main(String[] args) throws Exception {
            int port = 8080;
            new NettyTimeClient().connect(port, "127.0.0.1");
        }
    }

package com.netty.netty;
    
    import io.netty.buffer.ByteBuf;
    import io.netty.buffer.Unpooled;
    import io.netty.channel.ChannelHandlerAdapter;
    import io.netty.channel.ChannelHandlerContext;
    
    public class NettyTimeClientHandler extends ChannelHandlerAdapter {
    
        private final ByteBuf firstMessage;
    
        public NettyTimeClientHandler() {
            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);
        }
    }

摘自：Netty权威指南