netty学习（5）:netty实现注册中心和发送JSON数据到指定的客户端

ゝ一纸荒年。 2023-10-13 14:13 62阅读 0赞

### 1. 实现：在netty客户端实现netty客户端注册功能，netty客户端需要发送注册消息到netty服务端。 ###

### 2. 在父工程创建Message类，定义消息格式和消息类型 ###

定义消息类型：

package message;
    
    public enum MessageType {
        RegisterRequest,
        RegisterResponse,
    
        QueryRegisterRequest,
        QueryRegisterResponse,
    
        Request,
        Response
    }

定义Message

package message;
    
    import com.alibaba.fastjson.JSONObject;
    import lombok.Data;
    import java.nio.charset.StandardCharsets;
    import java.util.UUID;
    
    @Data
    public class Message extends JSONObject {
        private String uuid;
        private MessageType messageType;
        private String from; //消息来源
        private String to;
        private JSONObject data; //消息实体
        private JSONObject message = new JSONObject();
    
        public Message(MessageType messageType, String from, String to, JSONObject data) {
            this.uuid = UUID.randomUUID().toString();
            this.messageType = messageType == null ? MessageType.Request : messageType;
            this.from = from;
            this.to = to;
            this.data = data;
            message.put("uuid", this.uuid);
            message.put("messageType", messageType);
            message.put("from", from);
            message.put("to", to);
            message.put("data", data);
        }
    
        //序列化
        public byte[] toByte() {
            System.out.println("message:" + this.message.toJSONString());
            return this.message.toJSONString().getBytes(StandardCharsets.UTF_8);
        }
    
        //反序列化
        public static Message toMessage(String msg) {
            return (Message) JSONObject.parseObject(msg);
        }
    
        public String toString() {
            return this.message.toJSONString();
        }
    }

### 3. 服务端实现注册中心 ###

创建Register类，管理注册的客户端

package server.register;
    
    import io.netty.channel.Channel;
    import java.util.HashMap;
    
    public class Register {
        private static HashMap<String, Channel> registerTable = new HashMap<>();
    
        private Register() {
    
        }
    
        public static void addServer(String name, Channel channel) {
            registerTable.put(name, channel);
            System.out.println(name + "注册成功！");
        }
    
        public static void removeServer(String name, Channel channel) {
            registerTable.remove(name);
        }
    
        public static Channel getServer(String name) {
            return registerTable.get(name);
        }
    
        public static HashMap<String, Channel> getAllServer() {
            return registerTable;
        }
    }

修改NettyServiceHandler，对服务器接收的消息根据类型处理，如果是注册消息，则去注册，请求消息则发送到相应的客户端。

package server.netty;
    
    import com.alibaba.fastjson.JSONObject;
    import io.netty.channel.Channel;
    import io.netty.channel.ChannelHandlerContext;
    import io.netty.channel.SimpleChannelInboundHandler;
    import io.netty.channel.group.ChannelGroup;
    import io.netty.channel.group.DefaultChannelGroup;
    import io.netty.util.concurrent.GlobalEventExecutor;
    import server.register.Register;
    
    import java.util.HashMap;
    
    public class NettyServiceHandler extends SimpleChannelInboundHandler<String> {
        private static final ChannelGroup group = new DefaultChannelGroup(GlobalEventExecutor.INSTANCE);
    
        @Override
        public void channelActive(ChannelHandlerContext ctx) throws Exception {
            // 获取到当前与服务器连接成功的channel
            Channel channel = ctx.channel();
            group.add(channel);
            System.out.println(channel.remoteAddress() + " 上线," + "在线数量：" + group.size());
        }
    
        @Override
        public void channelInactive(ChannelHandlerContext ctx) throws Exception {
            // 获取到当前要断开连接的Channel
            Channel channel = ctx.channel();
            System.out.println(channel.remoteAddress() + "下线，" + "在线数量：" + group.size());
        }
    
        @Override
        protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {
            Channel channel = ctx.channel();
            System.out.println("netty客户端" + channel.remoteAddress() + "发送过来的消息:" + msg);
            JSONObject message = JSONObject.parseObject(msg);
    //        group.forEach(ch -> { // JDK8 提供的lambda表达式
    //            if (ch != channel) {
    //                ch.writeAndFlush(msg + "\r\n");
    //            }
    //        });
            HandlerMessage(message, channel);
        }
    
        public void exceptionCaught(ChannelHandlerContext channelHandlerContext, Throwable throwable) throws Exception {
            throwable.printStackTrace();
            channelHandlerContext.close();
        }
    
        public void HandlerMessage(JSONObject message, Channel channel) {
            String messageType = message.getString("messageType");
            switch (messageType) {
                case "RegisterRequest":
                    message.put("channel", channel);
                    register(message);
                    break;
                case "QueryRegisterRequest":
                    break;
                default:
                    request(message);
            }
        }
    
        public void register(JSONObject message) {
            Register.addServer(message.getString("from"), (Channel) message.get("channel"));
        }
    
        public void request(JSONObject message) {
            Channel channel = Register.getServer(message.getString("to"));
            channel.writeAndFlush(message.toJSONString() + "\r\n");
        }
    
        public HashMap<String, Channel> queryRegister() {
            return Register.getAllServer();
        }
    }

### 4. 客户端自动注册 ###

客户端启动时把自己的信息发送到服务端

package client.netty;
    
    import io.netty.bootstrap.Bootstrap;
    import io.netty.channel.Channel;
    import io.netty.channel.EventLoopGroup;
    import io.netty.channel.nio.NioEventLoopGroup;
    import io.netty.channel.socket.nio.NioSocketChannel;
    import lombok.Getter;
    import lombok.extern.slf4j.Slf4j;
    import message.Message;
    import message.MessageType;
    import org.slf4j.Logger;
    import org.slf4j.LoggerFactory;
    import org.springframework.beans.factory.annotation.Value;
    import org.springframework.stereotype.Component;
    
    import javax.annotation.Resource;
    
    @Component
    @Slf4j
    public class NettyClient {
        public final static Logger logger = LoggerFactory.getLogger(NettyClient.class);
    
        @Resource
        private SocketInitializer socketInitializer;
    
        @Getter
        private Bootstrap bootstrap;
    
        @Getter
        private Channel channel;
    
        /**
         * netty服务监听端口
         */
        @Value("${netty.port:6666}")
        private int port;
    
        @Value("${netty.host:127.0.0.1}")
        private String host;
    
        @Value("${netty.name}")
        private String name;
        /**
         * 启动netty
         */
        public void start() {
            this.init();
            this.channel = this.bootstrap.connect(host, port).channel();
            logger.info("Netty connect on port: {}, the host {}, the channel {}", this.port, this.host, this.channel);
            //自动注册
            register();
        }
    
        /**
         * 初始化netty配置
         */
        private void init() {
            EventLoopGroup group = new NioEventLoopGroup();
            this.bootstrap = new Bootstrap();
            //设置线程组
            bootstrap.group(group)
                    .channel(NioSocketChannel.class) //设置客户端的通道实现类型
                    .handler(this.socketInitializer);
        }
    
        //netty发送消息
        public void sendMessage(String message) {
            this.channel.writeAndFlush(message + "\r\n");
        }
    
        //netty发送消息
        public void sendMessage(Message message) {
            this.channel.writeAndFlush(message.toString() + "\r\n");
        }
    
        public void register() {
            Message message = new Message(MessageType.RegisterRequest, name, null, null);
            sendMessage(message);
            logger.info("register");
        }
    }

### 5. 客户端RestController层接收消息 ###

RESTFUL风格，从url解析目标客户端的名称

package client.control;
    
    import client.netty.NettyClient;
    import com.alibaba.fastjson.JSONObject;
    import message.Message;
    import message.MessageType;
    import org.springframework.beans.factory.annotation.Value;
    import org.springframework.web.bind.annotation.*;
    import javax.annotation.Resource;
    
    @RestController
    @RequestMapping("/client1")
    public class NettyControl {
        @Value("${netty.name}")
        private String from;
    
        @Resource
        private NettyClient nettyClient;
    
        @PostMapping("/{to}/msg")
        public String sendMsg(@PathVariable("to") String to, @RequestBody JSONObject data) {
            Message message = new Message(MessageType.Request, from, to, data);
            this.nettyClient.sendMessage(message);
            return message.toString();
        }
    }

### 6. postman测试 ###

启动服务和两个客户端，客户端已经注册成功。  
![在这里插入图片描述][e408dbac75f6426092237b5567842e7b.png_pic_center]  
client1发送到client2  
![在这里插入图片描述][ff6c89141d7c48ebb6e0207243054a4e.png]  
![在这里插入图片描述][7cf2b472809d443280084b8ba2ba0928.png_pic_center]  
client2发送到client1  
![在这里插入图片描述][1e1c66779ba54d7384452f89f283f059.png]  
![在这里插入图片描述][def32456c1644e0aa368aa61592de85a.png_pic_center]  
服务端收到的消息  
![在这里插入图片描述][95cac64c2a9c4f6eb757e361dfffeed2.png_pic_center]

[e408dbac75f6426092237b5567842e7b.png_pic_center]: https://img-blog.csdnimg.cn/e408dbac75f6426092237b5567842e7b.png#pic_center
[ff6c89141d7c48ebb6e0207243054a4e.png]: https://img-blog.csdnimg.cn/ff6c89141d7c48ebb6e0207243054a4e.png
[7cf2b472809d443280084b8ba2ba0928.png_pic_center]: https://img-blog.csdnimg.cn/7cf2b472809d443280084b8ba2ba0928.png#pic_center
[1e1c66779ba54d7384452f89f283f059.png]: https://img-blog.csdnimg.cn/1e1c66779ba54d7384452f89f283f059.png
[def32456c1644e0aa368aa61592de85a.png_pic_center]: https://img-blog.csdnimg.cn/def32456c1644e0aa368aa61592de85a.png#pic_center
[95cac64c2a9c4f6eb757e361dfffeed2.png_pic_center]: https://img-blog.csdnimg.cn/95cac64c2a9c4f6eb757e361dfffeed2.png#pic_center