Netty(3)-实现客户端与服务端的双向通信

爱被打了一巴掌 2023-07-03 06:29 10阅读 0赞

### 文章目录 ###

*   *   *  一.基本思路
         *  二.通信流程
         *  三.代码实现

### 一.基本思路 ###

读写逻辑处理均是启动阶段通过给逻辑处理链Pipeline添加逻辑处理器实现连接数据的读写逻辑。

1.  客户端连接成功回调逻辑处理器的`channelActive()`方法
2.  客户端和服务端接收到对方的数据回调用各自逻辑处理器的`channelRead()`方法。
3.  客户端和服务端向对方写数据调用`writeAndFlush()`方法
4.  客户端和服务端交互的二进制数据传输载体为`ByteBuf`

### 二.通信流程 ###

![\[外链图片转存失败,源站可能有防盗链机制,建议将图片保存下来直接上传(img-lxx6KkVY-1580725870430)(http://note.youdao.com/yws/res/9840/76DC2AB9464A4D1882346E496B1C9518)\]][img-lxx6KkVY-1580725870430_http_note.youdao.com_yws_res_9840_76DC2AB9464A4D1882346E496B1C9518]

### 三.代码实现 ###

*  NIOServer

/** * @Auther: ARong * @Description: 服务端-客户端双向通信，服务端在接收到客户端信息后向客户端发出响应 */
    public class NIOServer { 
        public static void main(String[] args) { 
            ServerBootstrap serverBootstrap = new ServerBootstrap();
            NioEventLoopGroup bossGroup = new NioEventLoopGroup(); // 监听组
            NioEventLoopGroup workerGroup = new NioEventLoopGroup(); // 工作组
    
            serverBootstrap.group(bossGroup, workerGroup)
                    .channel(NioServerSocketChannel.class) //NIO模式
                    .childHandler(new ChannelInitializer<SocketChannel>() { 
                        @Override
                        // 初始化channel
                        protected void initChannel(SocketChannel ch) throws Exception { 
                            ch.pipeline().addLast(new FirstServerHandler());
                        }
                    }).bind(8000);
        }
    }

*  NIOClient

/** * @Auther: ARong * @Description: 服务端-客户端双向通信，客户端向服务端发送信息 */
    public class NIOClient { 
        public static void main(String[] args) throws InterruptedException { 
            Bootstrap bootstrap = new Bootstrap();
            NioEventLoopGroup group = new NioEventLoopGroup();
    
            bootstrap.group(group).channel(NioSocketChannel.class).handler(new ChannelInitializer<SocketChannel>() { 
                @Override
                protected void initChannel(SocketChannel ch) throws Exception { 
                    // 责任链模式，添加第一次连接的客户端处理逻辑
                    ch.pipeline().addLast(new FirstClientHandler());
                }
            });
    
            Channel channel = bootstrap.connect("127.0.0.1", 8000).channel();
            String message = String.format("HelloWorld From %s", new SimpleDateFormat("hh:mm:ss").format(new Date()));
            channel.writeAndFlush(message);
        }
    }

*  FirstServerHandler

/** * @Auther: ARong * @Description: 服务端被首次连接的处理逻辑 */
    public class FirstServerHandler extends ChannelInboundHandlerAdapter { 
        @Override
        /* * @Author ARong * @Description 接收到服务端消息时触发 * @Param [ctx, msg] * @return void **/
        public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception { 
            ByteBuf byteBuf = (ByteBuf) msg;
            System.out.println(String.format("服务端读取到数据%s From %s",
                    byteBuf.toString(Charset.forName("utf-8")),
                    getCurTime()));
    
            ByteBuf byteBuf1 = getByteBuf(ctx);
            ctx.channel().writeAndFlush(byteBuf1);
        }
    
        /* * @Author ARong * @Description 获取二进制抽象 ByteBuf * @Param [ctx] * @return io.netty.buffer.ByteBuf **/
        private ByteBuf getByteBuf(ChannelHandlerContext ctx) { 
            // 获取二进制抽象 ByteBuf
            ByteBuf buffer = ctx.alloc().buffer();
    
            // 准备数据，指定字符串的字符集为 utf-8
            String response = String.format("服务端返回HelloWorld From %s", getCurTime());
            byte[] bytes = response.getBytes(Charset.forName("utf-8"));
    
            // 填充数据到 ByteBuf
            buffer.writeBytes(bytes);
    
            return buffer;
        }
    
        private String getCurTime() { 
            return new SimpleDateFormat("hh:mm:ss").format(new Date());
        }
    }

*  FirstClientHandler

/** * @Auther: ARong * @Description: 首次连接的客户端处理逻辑 */
    public class FirstClientHandler extends ChannelInboundHandlerAdapter { 
        @Override
        /* * @Author ARong * @Description 客户端与服务端首次连接的处理逻辑 * @Param [ctx] * @return void **/
        public void channelActive(ChannelHandlerContext ctx) throws Exception { 
            // 编码数据
            ByteBuf byteBuf = getByteBuf(ctx);
            // 写回给服务端
            ctx.channel().writeAndFlush(byteBuf);
        }
    
        @Override
        /* * @Author ARong * @Description 接收到服务端消息时触发 * @Param [ctx, msg] * @return void **/
        public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception { 
            ByteBuf byteBuf = (ByteBuf) msg;
            System.out.println(String.format("客户端读取到数据%s From %s",
                    byteBuf.toString(Charset.forName("utf-8")),
                    getCurTime()));
        }
    
        /* * @Author ARong * @Description 获取二进制抽象 ByteBuf * @Param [ctx] * @return io.netty.buffer.ByteBuf **/
        private ByteBuf getByteBuf(ChannelHandlerContext ctx) { 
            // 获取二进制抽象 ByteBuf
            ByteBuf buffer = ctx.alloc().buffer();
    
            // 准备数据，指定字符串的字符集为 utf-8
            String response = String.format("客户端返回HelloWorld From %s", getCurTime());
            byte[] bytes = response.getBytes(Charset.forName("utf-8"));
    
            // 填充数据到 ByteBuf
            buffer.writeBytes(bytes);
    
            return buffer;
        }
    
        private String getCurTime() { 
            return new SimpleDateFormat("hh:mm:ss").format(new Date());
        }
    }

依次启动客户端和服务端，实现双向通信：

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9hcm9uZy5ibG9nLmNzZG4ubmV0_size_16_color_FFFFFF_t_70]

[img-lxx6KkVY-1580725870430_http_note.youdao.com_yws_res_9840_76DC2AB9464A4D1882346E496B1C9518]: https://img-blog.csdnimg.cn/20200203183119747.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9hcm9uZy5ibG9nLmNzZG4ubmV0,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9hcm9uZy5ibG9nLmNzZG4ubmV0_size_16_color_FFFFFF_t_70]: https://img-blog.csdnimg.cn/20200203183146511.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9hcm9uZy5ibG9nLmNzZG4ubmV0,size_16,color_FFFFFF,t_70