Implementation of distributed group chat based on springboot websocket

Warehouse Address

https://github.com/yemingfeng/jchat-server

function list

distributed
Multi-device login with the same account
group chat
Multiple devices
Simple authentication
Heartbeat check

rely

maven
jdk11
repeat

redis configuration

Redis uses localhost:6379 by default. If you need to modify host:port, you can modify application.yml

redis only to store user name / password

Source code analysis

Auth process

String username = ((ServletServerHttpRequest) request)
  .getServletRequest().getParameter(USERNAME);
String password = ((ServletServerHttpRequest) request)
  .getServletRequest().getParameter(PASSWORD);
User user = userService.register(username, password);
// 将 user 设置到 attributes 中
attributes.put(USER, user);
return true;

Connection creation

// 1. 添加 session
sessionService.add(session);
// 2. 按 username + sessionId 生成 redis key，并进行订阅，这样做可以支持多设备同一个帐号登录
MessageListener messageListener = (message, pattern) -> {
    
    
  log.info("Redis sub receive: [{}]", new String(message.getBody()));
  try {
    
    
    session.sendMessage(new TextMessage(message.getBody()));
  } catch (IOException e) {
    
    
    log.error("", e);
  }
};
redisMessageListenerContainer.addMessageListener(messageListener,
  new ChannelTopic(genSubKey(session)));
// 由于 session 会断开，需要保存下来，以待 removeListener
messageListenerMap.put(session, messageListener);

Listen for messages

// 获取所有在线的 session，然后通过 redis pub 功能转发消息
sessionService.getSessions()
  .forEach(session -> pubSubService.pub(session, textMessage));

Heartbeat check

// 核心逻辑是使用分桶策略，一共有 10 个桶，每个桶有对应的定时任务和延迟队列
// 延迟队列使用了 HeartbeatSessionTask， 其中 HeartbeatSessionTask 封装了 session 和对应的过期时间

static final int BUCKET_SIZE = 10;

// 每个 session 进入桶时，会根据 sessionId.hashCode() & BUCKET_SIZE 选择桶
bucket[Math.abs(session.getId().hashCode() % BUCKET_SIZE)].add(new HeartbeatSessionTask(session));

// 启动每个桶的定时任务
for (int i = 0; i < BUCKET_SIZE; i++) {
    
    
  bucket[i] = new DelayQueue<>();
  executors[i] = Executors.newSingleThreadExecutor();
  int index = i;

  executors[index].submit(() -> {
    
    
    while (true) {
    
    
      try {
    
    
        HeartbeatSessionTask task;
        while ((task = bucket[index].poll()) != null) {
    
    
          task.getSession().close();
          log.warn("[{}] is dead, so close", SessionUtil.getUsernameFromSession(task.session));
        }
      } catch (Exception e) {
    
    
        log.error("", e);
      }
      Thread.sleep(TimeUnit.SECONDS.toMillis(1));
    }
  });
}

use

Server start

After startup, it will monitor the localhost:8080 port,

where the websocket url is ws:localhost:8080/ws and the

interface for obtaining the number of online users is http://localhost:8080/session/page

shell test

Use wscat to test

wscat -c 'ws://localhost:8080/ws?username=aiden&password=123'

Front-end testing

Due to the simple account system, the username/password needs to be established when linking. If the username does not exist, the registration is successful; otherwise, it will be judged whether the username/password matches

such as ws://localhost:8080/ws?username=aiden&password=123. Make a connection
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