springboot integrated websocket quick start demo

3 min readFeb 26, 2024

一、websocket introduction

WebSocket is a full-duplex communication protocol based on TCP protocol，It allows the establishment of persistent, two-way communication connections between clients and servers。Compared with traditional HTTP request-response mode, WebSocket provides real-time, low-latency data transmission capabilities。Through WebSocket, the client and server can send messages to each other at any point in time to achieve real-time updates and instant communication functions.

二、code project

This experiment will guide you how to integrate and use WebSocket in Spring Boot

maven dependency

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <artifactId>springboot-demo</artifactId>
        <groupId>com.et</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>
<artifactId>websocket</artifactId>
    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-autoconfigure</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-websocket</artifactId>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>2.0.40</version>
            <scope>compile</scope>
        </dependency>
    </dependencies>
</project>

properties

server:
  port: 8088

websocket configuration

package com.et.websocket.config;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.socket.config.annotation.EnableWebSocket;
import org.springframework.web.socket.server.standard.ServerEndpointExporter;
@Configuration
@EnableWebSocket
public class WebSocketConfiguration {
    @Bean
    public ServerEndpointExporter serverEndpointExporter() {
        return new ServerEndpointExporter();
    }
}

websocket service

WebSocket has four events in all ，Corresponding to the definitions of JSR-356@OnOpen、@OnMessage、@OnClose、@OnError annotation。

@OnOpen：open websocket
@OnClose：close WebSocket
@OnMessage：receive messgae
@OnError：define a error

package com.et.websocket.channel;
import com.alibaba.fastjson2.JSON;
import com.alibaba.fastjson2.JSONObject;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Component;
import org.springframework.util.StringUtils;
import javax.websocket.*;
import javax.websocket.server.PathParam;
import javax.websocket.server.ServerEndpoint;
import java.io.IOException;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.atomic.AtomicInteger;
@ServerEndpoint("/websocket/{userId}")
@Component
public class WebSocketServer {
    private static final Logger log = LoggerFactory.getLogger(WebSocketServer.class);
    /**
     * current online 
     */
    private static AtomicInteger onlineCount = new AtomicInteger(0);
    /**
     * save WebSocketServer object
     */
    private static ConcurrentHashMap<String, WebSocketServer> webSocketMap = new ConcurrentHashMap<>();
    /**
     * session
     */
    private Session session;
    /**
     * receive userId
     */
    private String userId = "";
    /**
     * invoke when websocket connection is built
     */
    @OnOpen
    public void onOpen(Session session, @PathParam("userId") String userId) {
        this.session = session;
        this.userId = userId;
        if (webSocketMap.containsKey(userId)) {
            webSocketMap.remove(userId);
            webSocketMap.put(userId, this);
        } else {
            webSocketMap.put(userId, this);
            addOnlineCount();
        }
        log.info("用户连接:" + userId + ",当前在线人数为:" + getOnlineCount());
        try {
            sendMessage("连接成功！");
        } catch (IOException e) {
            log.error("用户:" + userId + ",网络异常!!!!!!");
        }
    }
    /**
     * 连接关闭调用的方法
     */
    @OnClose
    public void onClose() {
        if (webSocketMap.containsKey(userId)) {
            webSocketMap.remove(userId);
            subOnlineCount();
        }
        log.info("用户退出:" + userId + ",当前在线人数为:" + getOnlineCount());
    }
    /**
     * 收到客户端消息后调用的方法
     *
     * @param message 客户端发送过来的消息
     */
    @OnMessage
    public void onMessage(String message, Session session) {
        log.info("用户消息:" + userId + ",报文:" + message);
        if (!StringUtils.isEmpty(message)) {
            try {
                JSONObject jsonObject = JSON.parseObject(message);
                jsonObject.put("fromUserId", this.userId);
                String toUserId = jsonObject.getString("toUserId");
                if (!StringUtils.isEmpty(toUserId) && webSocketMap.containsKey(toUserId)) {
                    webSocketMap.get(toUserId).sendMessage(jsonObject.toJSONString());
                } else {
                    log.error("请求的 userId:" + toUserId + "不在该服务器上");
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }
    /**
     * 发生错误时调用
     *
     * @param session
     * @param error
     */
    @OnError
    public void onError(Session session, Throwable error) {
        log.error("用户错误:" + this.userId + ",原因:" + error.getMessage());
        error.printStackTrace();
    }
    /**
     * 实现服务器主动推送
     */
    public void sendMessage(String message) throws IOException {
        this.session.getBasicRemote().sendText(message);
    }
    public static synchronized AtomicInteger getOnlineCount() {
        return onlineCount;
    }
    public static synchronized void addOnlineCount() {
        WebSocketServer.onlineCount.getAndIncrement();
    }
    public static synchronized void subOnlineCount() {
        WebSocketServer.onlineCount.getAndDecrement();
    }
}

start class

package com.et.websocket;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
public class DemoApplication {
   public static void main(String[] args) {
      SpringApplication.run(DemoApplication.class, args);
   }
}

code repository

https://github.com/Harries/springboot-demo

三、test

open postman，create two websocket test connections ws://127.0.0.1:8088/websocket/wupx，clickconnectionbutton，the message record will add a message"连接成功！"。

input ws://127.0.0.1:8088/websocket/huxy，clickconnectionbutton，then return the first page and input{"toUserId":"huxy","message":"i love you"}，clicksend，the second page will receive a message{"fromUserId":"wupx","message":"i love you","toUserId":"huxy"}。

console output

2024-02-26 15:26:48.699 INFO 27848 --- [nio-8088-exec-2] c.et.websocket.channel.WebSocketServer : 用户连接:huxy,当前在线人数为:1
2024-02-26 15:26:56.581 INFO 27848 --- [nio-8088-exec-4] c.et.websocket.channel.WebSocketServer : 用户连接:wupx,当前在线人数为:2
2024-02-26 15:27:26.401 INFO 27848 --- [nio-8088-exec-5] c.et.websocket.channel.WebSocketServer : 用户消息:wupx,报文:{"toUserId":"huxy","message":"i love you"}