websocket+redis动态订阅和动态取消订阅的实现示例

目录

• 原理
• redis订阅监听类
• webSocket订阅推送类
• 项目地址
• Update20220415

原理

websocket的订阅就是在前后端建立ws连接之后，前端通过发送一定格式的消息，后端解析出来去订阅或者取消订阅redis频道。

订阅频道消息格式:

{
    "cmd":"subscribe",
    "topic":[
        "topic_name"
    ]
}

模糊订阅格式

{
    "cmd":"psubscribe",
    "topic":[
        "topic_name"
    ]
}

取消订阅格式

{
    "cmd":"unsubscribe",
    "topic":[
        "topic_name"
    ]
}

两个核心类，一个是redis的订阅监听类，一个是websocket的发布订阅类。

redis订阅监听类

package com.curtain.core;

import com.curtain.config.GetBeanUtil;
import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Component;
import redis.clients.jedis.Jedis;
import redis.clients.jedis.JedisPool;
import redis.clients.jedis.JedisPubSub;

import java.util.Arrays;

/**
* @Author Curtain
* @Date 2021/6/7 14:27
* @Description
*/
@Component
@Slf4j
public class RedisPubSub extends JedisPubSub {
  private JedisPool jedisPool = GetBeanUtil.getBean(JedisPool.class);
  private Jedis jedis;

  //订阅
  public void subscribe(String... channels) {
    jedis = jedisPool.getResource();
    try {
      jedis.subscribe(this, channels);
    } catch (Exception e) {
      log.error(e.getMessage());
      if (jedis != null)
        jedis.close();
      //遇到异常后关闭连接重新订阅
      log.info("监听遇到异常，四秒后重新订阅频道：");
      Arrays.asList(channels).forEach(s -> {log.info(s);});
      try {
        Thread.sleep(4000);
      } catch (InterruptedException interruptedException) {
        interruptedException.printStackTrace();
      }
      subscribe(channels);
    }
  }

  //模糊订阅
  public void psubscribe(String... channels) {
    Jedis jedis = jedisPool.编程客栈getResource();
    try {
      jedis.psubscribe(this, channels);
    } catch (ArithmeticException e) {//取消订阅故意造成的异常
      if (jedis != null)
        jedis.close();
    } catch (Exception e) {
      log.error(e.getMessage());
      if (jedis != null)
        jedis.close();
      //遇到异常后关闭连接重新订阅
      log.info("监听遇到异常，四秒后重新订阅频道：");
      Arrays.asList(channels).forEach(s -> {log.info(s);});
      try {
        Thread.sleep(4000);
      } catch (InterruptedException interruptedException) {
        interruptedException.printStackTrace();
      }
      psubscribe(channels);
    }
  }

  public void unsubscribeAndClose(String... channels){
    unsubscribe(channels);
    if (jedis != null && !isSubscribed())
      jedis.close();
  }

  public void punsubscribeAndClose(String... channels){
    punsubscribe(channels);
    if (jedis != null && !isSubscribed())
      jedis.close();
  }

  @Override
  public void onSubscribe(String channel, int subscribedChannels) {
    log.info("subscribe redis channel：" + channel + ", 线程id：" + Thread.currentThread().getId());
  }

  @Override
  public void onPSubscribe(String pattern, int subscribedChannels) {
    log.info("psubscribe redis channel：" + pattern + ", 线程id：" + Thread.currentThread().getId());
  }

  @Override
  public void onPMessage(String pattern, String channel, String message) {
    log.info("receive from redis channal: " + channel + ",pattern: " + pattern + ",message：" + message + ", 线程id：" + Thread.currentThread().getId());
    WebSocketServer.publish(message, pattern);
    WebSocketServer.publis开发者_Kafkah(message, channel);

  }

  @Override
  public void onMessage(String channel, String message) {
    log.info("receive from redis channal: " + channel + ",message：" + message + ", 线程id：" + Thread.currentThread().getId());
    WebSocketServer.publish(message, channel);
  }

  @Override
  public void onUnsubscribe(String channel, int subscribedChannels) {
    log.info("unsubscribe redis channel：" + channel);
  }

  @Override
  public void onPUnsubscribe(String pattern, int subscribedChannels) {
    log.info("punsubscribe redis channel：" + pattern);
  }
}

1.jedis监听redis频道的时候如果遇见异常会关闭连接导致后续没有监听该频道，所以这里在subscribe捕获到异常的时候会重新创建一个jedis连接订阅该redis频道。

webSocket订阅推送类

这个类会有两个ConcurrentHashMap<String, ConcurrentHashMap<String, WebSocketServer>>类型类变量，分别存储订阅和模糊订阅的信息。

外面一层的String对应的值是topic_name,里面一层的String对应的值是sessionId。前端发送过来的消息里面对应的这三类操作其实就是对这两个map里面的。

还有个ConcurrentHashMap<String, RedisPubSub>类型的变量，存储的是事件-RedisPubSub，便于取消订阅的时候找到监听该频道（事件）的RedisPubSub对象。

信息进行增加或者删除;后端往前端推送数据也会根据不同的topic_name推送到不同的订阅者这边。

package com.curtain.core;

import com.alibaba.fastjson.JSON;
import com.curtain.config.WebsocketProperties;
import com.curtain.service.Cancelable;
import com.curtain.service.impl.TaskExecuteService;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

import javax.websocket.*;
import javax.websocket.server.ServerEndpoint;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.nio.ByteBuffer;
import java.util.*;
import java.util.concurrent.ConcurrentHashMap;


/**
* @Author Curtain
* @Date 2021/5/14 16:49
* @Description
*/
@ServerEndpoint("/ws")
@Component
@Slf4j
public class WebSocketServer {
  /**
  * concurrent包的线程安全Set，用来存放每个客户端对应的MyWebSocket对象。
  */
  private static volatile ConcurrentHashMap<String, ConcurrentHashMap<String, WebSocketServer>> webSocketMap = new ConcurrentHashMap<>();
  /**
  * 存放psub的事件
  **/
  private static volatile ConcurrentHashMap<String, ConcurrentHashMap<String, WebSocketServer>> pWebSocketMap = new ConcurrentHashMap<>();
  /**
  * 存放topic(pattern)-对应的RedisPubsub
  */
  private static volatile ConcurrentHashMap<String, RedisPubSub> redisPubSubMap = new ClOBxPoncurrentHashMap<>();
  /**
  * 与某个客户端的连接会话，需要通过它来给客户端发送数据
  */
  private Session session;
  private String sessionId = "";
  //要注入的对象
  private static TaskExecuteService executeService;
  private static WebsocketProperties properties;

  private Cancelable cancelable;

  @Autowired
  public void setTaskExecuteService(TaskExecuteService taskExecuteService) {
    WebSocketServer.executeService = taskExecuteService;
  }

  @Autowired
  public void setWebsocketProperties(WebsocketProperties properties) {
    WebSocketServer.properties = properties;
  }

  /**
  * 连接建立成功调用的方法
  */
  @OnOpen
  public void onOpen(Session session) {
    this.session = session;
    this.sessionId = session.getId();
    //构造推送数据
    Map pubHeader = new HashMap();
    pubHeader.put("name", "connect_status");
    pubHeader.put("type", "create");
    pubHeader.put("from", "pubsub");
    pubHeader.put("time", new Date().getTime() / 1000);
    Map pubPayload = new HashMap();
    pubPayload.put("status", "success");
    Map pubMap = new HashMap();
    pubMap.put("header", pubHeader);
    pubMap.put("payload", pubPayload);
    sendMessage(JSON.toJSONString(pubMap));
    cancelable = executeService.runPeriodly(() -> {
      try {
        if (cancelable != null && !session.isOpen()) {
          log.info("断开连接，停止发送ping");
          cancelable.cancel();
        } else {
          String data = "ping";
          ByteBuffer payload = ByteBuffer.wrap(data.getBytes());
          session.getBasicRemote().sendPing(payload);
        }
      } catch (IOException e) {
        e.printStackTrace();
      }
    }, properties.getPeriod());

  }

  @OnMessage
  public void onMessage(String message) {
    synchronized (session) {
      Map msgMap = (Map) JSON.parse(message);
      String cmd = (String) msgMap.get("cmd");
      //订阅消息
      if ("subscribe".equals(cmd)) {
        List<String> topics = (List<String>) msgMap.get("topic");
        //本地记录订阅信息
        for (int i = 0; i < topics.size(); i++) {
          String topic = topics.get(i);
          log.info("============================subscribe-start============================");
          log.info("sessionId：" + this.sessionId + "，开始订阅：" + topic);
          if (webSocketMap.containsKey(topic)) {//有人订阅过了
            webSocketMap.get(topic).put(this.sessionId, this);
          } else {//之前还没人订阅过，所以需要订阅redis频道
            ConcurrentHashMap<String, WebSocketServer> map = new ConcurrentHashMap<>();
            map.put(this.sessionId, this);
            webSocketMap.put(topic, map);
            new Thread(() -> {
              RedisPubSub redisPubSub = new RedisPubSub();
              //存入map
              redisPubSubMap.put(topic, redisPubSub);
              redisPubSub.subscribe(topic);
            }).start();
          }
          log.info("sessionId：" + this.sessionId + "，完成订阅：" + topic);
          log();
          log.info("============================subscribe-end============================");
        }
      }
      //psubscribe
      if ("psubscribe".equals(cmd)) {
        List<String> topics = (List<String>) msgMap.get("topic");
        //本地记录订阅信息
        for (int i = 0; i < topics.size(); i++) {
          String topic = topics.get(i);
          log.info("============================psubscribe-start============================");
          log.info("sessionId：" + this.sessionId + "，开始模糊订阅：" + topic);
          if (pWebSocketMap.containsKey(topic)) {//有人订阅过了
            pWebSocketMap.get(topic).put(this.sessionId, this);
          } else {//之前还没人订阅过，所以需要订阅redis频道
            ConcurrentHashMap<String, WebSocketServer> map = new ConcurrentHashMap<>();
            map.put(this.sessionId, this);
            pWebSocketMap.put(topic, map);
            new Thread(() -> {
              RedisPubSub redisPubSub = new RedisPubSub();
              //存入map
              redisPubSubMap.put(topic, redisPubSub);
              redisPubSub.psubscribe(topic);
            }).start();
          }
          log.info("sessionId：" + this.sessionId + "，完成模糊订阅：" + topic);
          log();
          log.info("============================psubscribe-end============================");
        }
      }
      //取消订阅
      if ("unsubscribe".equals(cmd)) {
        List<String> topics = (List<String>) msgMap.get("topic");
        //删除本地对应的订阅信息
        for (String topic : topics) {
          log.info("============================unsubscribe-start============================");
          log.info("sessionId：" + this.sessionId + "，开始删除订阅：" + topic);
          if (webSocketMap.containsKey(topic)) {
            ConcurrentHashMap<String, WebSocketServer> map = webSocketMap.get(topic);
            map.remove(this.sessionId);
            if (map.size() == 0) {//如果这个频道没有用户订阅了，则取消订阅该redis频道
              webSocketMap.remove(topic);
              redisPubSubMap.get(topic).unsubscribeAndClose(topic);
              redisPubSubMap.remove(topic);
            }
          }
          if (pWebSocketMap.containsKey(topic)) {
            ConcurrentHashMap<String, WebSocketServer> map = pWebSocketMap.get(topic);
            map.remove(this.sessionId);
            if (map.size() == 0) {//如果这个频道没有用户订阅了，则取消订阅该redis频道
              pWebSocketMap.remove(topic);
              redisPubSubMap.get(topic).punsubscribeAndClose(topic);
              redisPubSubMap.remove(topic);
            }
          }
          log.info("sessionId：" + this.sessionId + "，完成删除订阅：" + topic);
          log();
          log.info("============================unsubscribe-end============================");
        }
      }
    }
  }

  @OnMessage
  public void onPong(PongMessage pongMessage) {
    try {
      log.debug(new String(pongMessage.getApplicationData().array(), "utf-8") + "接收到pong");
    } catch (UnsupportedEncodingException e) {
      e.printStackTrace();
    }
  }

  /**
  * 连接关闭调用的方法
  */
  @OnClose
  public void onClose() {
    synchronized (session) {
      log.info("====http://www.devze.com========================onclose-start============================");
      //删除订阅
      Iterator iterator = webSocketMap.keySet().iterator();
      while (iterator.hasNext()) {
        String topic = (String) iterator.next();
        ConcurrentHashMap<String, WebSocketServer> map = webSocketMap.get(topic);
        map.remove(this.sessionId);
        if (map.size() == 0) {//如果这个频道没有用户订阅了，则取消订阅该redis频道
          webSocketMap.remove(topic);
          redisPubSubMap.get(topic).unsubscribeAndClose(topic);
          redisPubSubMap.remove(topic);
        }
      }
      //删除模糊订阅
      Iterator iteratorP = pWebSocketMap.keySet().iterator();
      while (iteratorP.hasNext()) {
        String topic = (String) iteratorP.next();
        ConcurrentHashMap<String, WebSocketServer> map = pWebSocketMap.get(topic);
        map.remove(this.sessionId);
        if (map.size() == 0) {//如果这个频道没有用户订阅了，则取消订阅该redis频道
          pWebSocketMap.remove(topic);
          redisPubSubMap.get(topic).punsubscribeAndClose(topic);
          redisPubSubMap.remove(topic);
        }
      }
      log.info("sessionId：" + this.sessionId + "，断开连接：");
      //debug
      log();
      log.info("============================onclose-end============================");
    }
  }


  /**
  * @param session
  * @param error
  */
  @OnError
  public void onError(Session session, Throwable error) {
    synchronized (session) {
      log.info("============================onError-start============================");
      log.error("用户错误,sessionId:" + session.getId() + ",原因:" + error.getMessage());
      error.printStackTrace();
      log.info("关闭错误用户对应的连接");
      //删除订阅
      Iterator iterator = webSocketMap.keySet().iterator();
      while (iterator.hasNext()) {
        String topic = (String) iterator.next();
        ConcurrentHashMap<String, WebSocketServer> map = webSocketMap.get(topic);
        map.remove(this.sessionId);
        if (map.size() == 0) {//如果这个频道没有用户订阅了，则取消订阅该redis频道
          webSocketMap.remove(topic);
          redisPubSubMap.get(topic).unsubscribeAndClose(topic);
          redisPubSubMap.remove(topic);
        }
      }
      //删除模糊订阅
      Iterator iteratorP = pWebSocketMap.keySet().iterator();
      while (iteratorP.hasNext()) {
        String topic = (String) iteratorP.next();
        ConcurrentHashMap<String, WebSocketServer> map = pWebSocketMap.get(topic);
        map.remove(this.sessionId);
        if (map.size() == 0) {//如果这个频道没有用户订阅了，则取消订阅该redis频道
          pWebSocketMap.remove(topic);
          redisPubSubMap.get(topic).punsubscribeAndClose(topic);
          redisPubSubMap.remove(topic);
        }
      }
      log.info("完成错误用户对应的连接关闭");
      //debug
      log();
      log.info("============================onError-end============================");
    }
  }

  /**
  * 实现服务器主动推送
  */
  public void sendMessage(String message) {
    synchronized (session) {
      try {
        this.session.getBasicRemote().sendText(message);
      } catch (IOException e) {
        e.printStackTrace();
      }
    }
  }

  public static void publish(String msg, String topic) {
    ConcurrentHashMap<String, WebSocketServer> map = webSocketMap.get(topic);
    if (map != null && map.values() != null) {
      for (WebSocketServer webSocketServer : map.values())
        webSocketServer.sendMessage(msg);
    }
    map = pWebSocketMap.get(topic);
    if (map != null && map.values() != null) {
      for (WebSocketServer webSocketServer : map.values())
        webSocketServer.sendMessage(msg);
    }
  }

  private void log() {
    log.info("<<<<<<<<<<<完成操作后，打印订阅信息开始>>>>>>>>>>");
    Iterator iterator1 = webSocketMap.keySet().iterator();
    while (iterator1.hasNext()) {
      String topic = (String) iterator1.next();
      log.info("topic：" + topic);
      Iterator iterator2 = webSocketMap.get(http://www.devze.comtopic).keySet().iterator();
      while (iterator2.hasNext()) {
        String session = (String) iterator2.next();
        log.info("订阅" + topic + "的sessionId：" + session);
      }
    }
    log.info("<<<<<<<<<<<完成操作后，打印订阅信息结束>>>>>>>>>>");
  }
}

项目地址

上面介绍了核心代码，下面是完整代码地址

https://github.com/Curtain-Wang/websocket-redis-subscribe.git

Update20220415

参考评论区老哥的建议，将redis订阅监听类里面的subscribe和psubscribe方法调整如下：

  //订阅
  @Override
  public void subscribe(String... channels) {
    boolean done = true;
    while (done){
      Jedis jedis = jedisPool.getResource();
      try {
        jedis.subscribe(this, channels);
        done = false;
      } catch (Exception e) {
        log.error(e.getMessage());
        if (jedis != null)
          jedis.close();
        //遇到异常后关闭连接重新订阅
        log.info("监听遇到异常，四秒后重新订阅频道：");
        Arrays.asList(channels).forEach(s -> {log.info(s);});
        try {
          Thread.sleep(4000);
        } catch (InterruptedException interruptedException) {
          interruptedException.printStackTrace();
        }
      }
    }
  }
  //模糊订阅
  @Override
  public void psubscribe(String... channels) {
    boolean done = true;
    while (done){
      Jedis jedis = jedisPool.getResource();
      try {
        jedis.psubscribe(this, channels);
        done = false;
      } catch (Exception e) {
        log.error(e.getMessage());
        if (jedis != null)
       编程客栈   jedis.close();
        //遇到异常后关闭连接重新订阅
        log.info("监听遇到异常，四秒后重新订阅频道：");
        Arrays.asList(channels).forEach(s -> {log.info(s);});
        try {
          Thread.sleep(4000);
        } catch (InterruptedException interruptedException) {
          interruptedException.printStackTrace();
        }
      }
    }
  }

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