Springboot+Netty+Websocket实现消息推送实例

前言

WebSocket 使得客户端和服务器之间的数据交换变得更加简单，允许服务端主动向客户端推送数据。在 WebSocket API 中，浏览器和服务器只需要完成一次握手，两者之间就直接可以创建持久性的连接，并进行双向数据传输。

Netty框架的优势

1. API使用简单，开发门槛低；
 2. 功能强大，预置了多种编解码功能，支持多种主流协议；
 3. 定制能力强，可以通过ChannelHandler对通信框架进行灵活地扩展；
 4. 性能高，通过与其他业界主流的NIO框架对比，Netty的综合性能最优；
 5. 成熟、稳定，Netty修复了已经发现的所有JDK NIO BUG，业务开发人员不需要再为NIO的BUG而烦恼

提示：以下是本篇文章正文内容，下面案例可供参考

一、引入netty依赖

<dependency>
   <groupId>io.netty</groupId>
   <artifactId>netty-all</artifactId>
   <version>4.1.48.Final</version>
</dependency>

二、使用步骤

1.引入基础配置类

package com.test.netty;

public enum Cmd {
 START("000", "连接成功"),
 WMESSAGE("001", "消息提醒"),
 ;
 private String cmd;
 private String desc;

 Cmd(String cmd, String desc) {
  this.cmd = cmd;
  this.desc = desc;
 }

 public String getCmd() {
  return cmd;
 }

 public String getDesc() {
  return desc;
 }
}

2.netty服务启动监听器

package com.test.netty;

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelOption;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.ApplicationRunner;
import org.springframework.context.annotation.Bean;
import org.springframework.stereotype.Component;

/**
 * @author test
 * <p>
 * 服务启动监听器
 **/
@Slf4j
@Component
public class NettyServer {

 @Value("${server.netty.port}")
 private int port;

 @Autowired
 private ServerChannelInitializer serverChannelInitializer;

 @Bean
 ApplicationRunner nettyRunner() {
  return args -> {
   //new 一个主线程组
   EventLoopGroup bossGroup = new NioEventLoopGroup(1);
   //new 一个工作线程组
   EventLoopGroup workGroup = new NioEventLoopGroup();
   ServerBootstrap bootstrap = new ServerBootstrap()
     .group(bossGroup, workGroup)
     .channel(NioServerSocketChannel.class)
     .childHandler(serverChannelInitializer)
     //设置队列大小
     .option(ChannelOption.SO_BACKLOG, 1024)
     // 两小时内没有数据的通信时,TCP会自动发送一个活动探测数据报文
     .childOption(ChannelOption.SO_KEEPALIVE, true);
   //绑定端口,开始接收进来的连接
   try {
    ChannelFuture future = bootstrap.bind(port).sync();
    log.info("服务器启动开始监听端口: {}", port);
    future.channel().closeFuture().sync();
   } catch (InterruptedException e) {
    e.printStackTrace();
   } finally {
    //关闭主线程组
    bossGroup.shutdownGracefully();
    //关闭工作线程组
    workGroup.shutdownGracefully();
   }
  };
 }
}

3.netty服务端处理器

package com.test.netty;

import com.test.common.util.JsonUtil;
import io.netty.channel.Channel;
import io.netty.channel.ChannelHandler;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.handler.codec.http.websocketx.TextWebSocketFrame;
import io.netty.handler.codec.http.websocketx.WebSocketServerProtocolHandler;
import lombok.Data;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

import java.net.URLDecoder;
import java.util.*;

/**
 * @author test
 * <p>
 * netty服务端处理器
 **/
@Slf4j
@Component
@ChannelHandler.Sharable
public class NettyServerHandler extends SimpleChannelInboundHandler<TextWebSocketFrame> {

 @Autowired
 private ServerChannelCache cache;
 private static final String dataKey = "test=";

 @Data
 public static class ChannelCache {
 }

 /**
  * 客户端连接会触发
  */
 @Override
 public void channelActive(ChannelHandlerContext ctx) throws Exception {
  Channel channel = ctx.channel();
  log.info("通道连接已打开，ID->{}......", channel.id().asLongText());
 }

 @Override
 public void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception {
  if (evt instanceof WebSocketServerProtocolHandler.HandshakeComplete) {
   Channel channel = ctx.channel();
   WebSocketServerProtocolHandler.HandshakeComplete handshakeComplete = (WebSocketServerProtocolHandler.HandshakeComplete) evt;
   String requestUri = handshakeComplete.requestUri();
   requestUri = URLDecoder.decode(requestUri, "UTF-8");
   log.info("HANDSHAKE_COMPLETE，ID->{}，URI->{}", channel.id().asLongText(), requestUri);
   String socketKey = requestUri.substring(requestUri.lastIndexOf(dataKey) + dataKey.length());
   if (socketKey.length() > 0) {
    cache.add(socketKey, channel);
    this.send(channel, Cmd.DOWN_START, null);
   } else {
    channel.disconnect();
    ctx.close();
   }
  }
  super.userEventTriggered(ctx, evt);
 }

 @Override
 public void channelInactive(ChannelHandlerContext ctx) throws Exception {
  Channel channel = ctx.channel();
  log.info("通道连接已断开，ID->{}，用户ID->{}......", channel.id().asLongText(), cache.getCacheId(channel));
  cache.remove(channel);
 }

 /**
  * 发生异常触发
  */
 @Override
 public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
  Channel channel = ctx.channel();
  log.error("连接出现异常，ID->{}，用户ID->{}，异常->{}......", channel.id().asLongText(), cache.getCacheId(channel), cause.getMessage(), cause);
  cache.remove(channel);
  ctx.close();
 }

 /**
  * 客户端发消息会触发
  */
 @Override
 protected void channelRead0(ChannelHandlerContext ctx, TextWebSocketFrame msg) throws Exception {
  try {
   // log.info("接收到客户端发送的消息：{}", msg.text());
   ctx.channel().writeAndFlush(new TextWebSocketFrame(JsonUtil.toString(Collections.singletonMap("cmd", "100"))));
  } catch (Exception e) {
   log.error("消息处理异常：{}", e.getMessage(), e);
  }
 }

 public void send(Cmd cmd, String id, Object obj) {
  HashMap<String, Channel> channels = cache.get(id);
  if (channels == null) {
   return;
  }
  Map<String, Object> data = new LinkedHashMap<>();
  data.put("cmd", cmd.getCmd());
  data.put("data", obj);
  String msg = JsonUtil.toString(data);
  log.info("服务器下发消息: {}", msg);
  channels.values().forEach(channel -> {
   channel.writeAndFlush(new TextWebSocketFrame(msg));
  });
 }

 public void send(Channel channel, Cmd cmd, Object obj) {
  Map<String, Object> data = new LinkedHashMap<>();
  data.put("cmd", cmd.getCmd());
  data.put("data", obj);
  String msg = JsonUtil.toString(data);
  log.info("服务器下发消息: {}", msg);
  channel.writeAndFlush(new TextWebSocketFrame(msg));
 }

}

4.netty服务端缓存类

package com.test.netty;

import io.netty.channel.Channel;
import io.netty.util.AttributeKey;
import org.springframework.stereotype.Component;

import java.util.HashMap;
import java.util.concurrent.ConcurrentHashMap;

@Component
public class ServerChannelCache {
 private static final ConcurrentHashMap<String, HashMap<String, Channel>> CACHE_MAP = new ConcurrentHashMap<>();
 private static final AttributeKey<String> CHANNEL_ATTR_KEY = AttributeKey.valueOf("test");

 public String getCacheId(Channel channel) {
  return channel.attr(CHANNEL_ATTR_KEY).get();
 }

 public void add(String cacheId, Channel channel) {
  channel.attr(CHANNEL_ATTR_KEY).set(cacheId);
  HashMap<String, Channel> hashMap = CACHE_MAP.get(cacheId);
  if (hashMap == null) {
   hashMap = new HashMap<>();
  }
  hashMap.put(channel.id().asShortText(), channel);
  CACHE_MAP.put(cacheId, hashMap);
 }

 public HashMap<String, Channel> get(String cacheId) {
  if (cacheId == null) {
   return null;
  }
  return CACHE_MAP.get(cacheId);
 }

 public void remove(Channel channel) {
  String cacheId = getCacheId(channel);
  if (cacheId == null) {
   return;
  }
  HashMap<String, Channel> hashMap = CACHE_MAP.get(cacheId);
  if (hashMap == null) {
   hashMap = new HashMap<>();
  }
  hashMap.remove(channel.id().asShortText());
  CACHE_MAP.put(cacheId, hashMap);
 }
}

5.netty服务初始化器

package com.test.netty;

import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.socket.SocketChannel;
import io.netty.handler.codec.http.HttpObjectAggregator;
import io.netty.handler.codec.http.HttpServerCodec;
import io.netty.handler.codec.http.websocketx.WebSocketServerProtocolHandler;
import io.netty.handler.stream.ChunkedWriteHandler;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

/**
 * @author test
 * <p>
 * netty服务初始化器
 **/
@Component
public class ServerChannelInitializer extends ChannelInitializer<SocketChannel> {

 @Autowired
 private NettyServerHandler nettyServerHandler;

 @Override
 protected void initChannel(SocketChannel socketChannel) throws Exception {
  ChannelPipeline pipeline = socketChannel.pipeline();
  pipeline.addLast(new HttpServerCodec());
  pipeline.addLast(new ChunkedWriteHandler());
  pipeline.addLast(new HttpObjectAggregator(8192));
  pipeline.addLast(new WebSocketServerProtocolHandler("/test.io", true, 5000));
  pipeline.addLast(nettyServerHandler);
 }
}

6.html测试

<!DOCTYPE HTML>
<html>
 <head>
 <meta charset="utf-8">
 <title>test</title>

  <script type="text/javascript">
   function WebSocketTest()
   {
   if ("WebSocket" in window)
   {
    alert("您的浏览器支持 WebSocket!");

    // 打开一个 web socket
    var ws = new WebSocket("ws://localhost:port/test.io");

    ws.onopen = function()
    {
     // Web Socket 已连接上，使用 send() 方法发送数据
     ws.send("发送数据");
     alert("数据发送中...");
    };

    ws.onmessage = function (evt)
    {
     var received_msg = evt.data;
     alert("数据已接收...");
    };

    ws.onclose = function()
    {
     // 关闭 websocket
     alert("连接已关闭...");
    };
   }

   else
   {
    // 浏览器不支持 WebSocket
    alert("您的浏览器不支持 WebSocket!");
   }
   }
  </script>

 </head>
 <body>

  <div id="sse">
   <a href="javascript:WebSocketTest()" rel="external nofollow" >运行 WebSocket</a>
  </div>

 </body>
</html>

7.vue测试

mounted() {
   this.initWebsocket();
  },
  methods: {
   initWebsocket() {
    let websocket = new WebSocket('ws://localhost:port/test.io?test=123456');
    websocket.onmessage = (event) => {
     let msg = JSON.parse(event.data);
     switch (msg.cmd) {
      case "000":
       this.$message({
        type: 'success',
        message: "建立实时连接成功！",
        duration: 1000
       })
       setInterval(()=>{websocket.send("heartbeat")},60*1000);
       break;
      case "001":
       this.$message.warning("收到一条新的信息，请及时查看！")
       break;
     }
    }
    websocket.onclose = () => {
     setTimeout(()=>{
      this.initWebsocket();
     },30*1000);
    }
    websocket.onerror = () => {
     setTimeout(()=>{
      this.initWebsocket();
     },30*1000);
    }
   },
  },
![在这里插入图片描述](https://img-blog.csdnimg.cn/20210107160420568.jpg?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3d1X3Fpbmdfc29uZw==,size_16,color_FFFFFF,t_70#pic_center)

8.服务器下发消息

@Autowired
	private NettyServerHandler nettyServerHandler;
nettyServerHandler.send(CmdWeb.WMESSAGE, id, message);

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