SpringBoot WebSocket server creation

import maven

<!--websocket-->
      <dependency>
          <groupId>org.springframework.boot</groupId>
          <artifactId>spring-boot-starter-websocket</artifactId>
      </dependency>

Create a new WebSocket configuration file

import org.springframework.context.annotation.Bean;
import org.springframework.stereotype.Component;
import org.springframework.web.socket.server.standard.ServerEndpointExporter;

@Component
public class WebSocketConfig {
    
    

    @Bean
    public ServerEndpointExporter serverEndpointExporter(){
    
    

        return new ServerEndpointExporter();
    }
}

Create a new WebSocket service

import java.io.IOException;
import java.util.concurrent.CopyOnWriteArraySet;

import javax.websocket.OnClose;
import javax.websocket.OnError;
import javax.websocket.OnMessage;
import javax.websocket.OnOpen;
import javax.websocket.Session;
import javax.websocket.server.PathParam;
import javax.websocket.server.ServerEndpoint;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.EnvironmentAware;
import org.springframework.core.env.Environment;
import org.springframework.stereotype.Component;

@Component
@ServerEndpoint("/webSocket/{sid}")
public class WebSocketServer implements EnvironmentAware {
    
    
    //静态变量，用来记录当前在线连接数。应该把它设计成线程安全的。
    private static int onlineCount = 0;

    //concurrent包的线程安全Set，用来存放每个客户端对应的MyWebSocket对象。若要实现服务端与单一客户端通信的话，可以使用Map来存放，其中Key可以为用户标识
    private static CopyOnWriteArraySet<WebSocketServer> webSocketSet = new CopyOnWriteArraySet<WebSocketServer>();

    private static Environment globalEnvironment;

    //接收sid
    private String sid="";

    //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;

    @Autowired
    private Environment environment;

    /**
     * 连接建立成功调用的方法
     *
     * @param session 可选的参数。session为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
     */
    @OnOpen
    public void onOpen(Session session,@PathParam("sid") String sid) {
    
    
        //防止重复连接
        for (WebSocketServer item : webSocketSet) {
    
    
            if (item.sid.equals(sid)) {
    
    
                webSocketSet.remove(item);
                subOnlineCount();           //在线数减1
                break;
            }
        }

        this.session = session;
        this.environment = globalEnvironment;
        webSocketSet.add(this);     //加入set中
        addOnlineCount();           //在线数加1
        System.out.println("有新用户连接，连接名:"+sid+",当前在线人数为" + getOnlineCount());
        this.sid=sid;

    }

    /**
     * 连接关闭调用的方法
     */
    @OnClose
    public void onClose() {
    
    
        webSocketSet.remove(this);  //从set中删除
        subOnlineCount();           //在线数减1
        System.out.println("连接关闭："+sid+"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
     * @param session 可选的参数
     */
    @OnMessage
    public void onMessage(String message, Session session) {
    
    
        System.out.println("收到来自:"+sid+"的信息:"+message);
//        //群发消息
        for (WebSocketServer item : webSocketSet) {
    
    
            try {
    
    
                System.out.println("推送消息到:"+sid+"，推送内容:"+message);
                item.sendMessage("服务器返回："+message);
            } catch (IOException e) {
    
    
                e.printStackTrace();
                continue;
            }
        }

    }

    /**
     * 发生错误时调用
     */
    @OnError
    public void onError(Session session, Throwable error) {
    
    
        System.out.println("发生错误");
        error.printStackTrace();
    }

    /**
     * 这个方法与上面几个方法不一样。没有用注解，是根据自己需要添加的方法。
     */
    public void sendMessage(String message) throws IOException {
    
    
        this.session.getBasicRemote().sendText(message);
        //this.session.getAsyncRemote().sendText(message);
    }

    /**
     * 群发自定义消息
     * */
    public static void sendInfo(String message,@PathParam("sid") String sid) throws IOException {
    
    
        //log.info("推送消息到窗口"+sid+"，推送内容:"+message);
        System.out.println("推送消息到:"+sid+"，推送内容:"+message);
        for (WebSocketServer item : webSocketSet) {
    
    
            try {
    
    
                //这里可以设定只推送给这个sid的，为null则全部推送
                if(sid==null||sid.length()==0) {
    
    
                    item.sendMessage(message);
                }else if(item.sid.equals(sid)){
    
    
                    item.sendMessage(message);
                }
            } catch (IOException e) {
    
    
                continue;
            }
        }
    }

    //推送给指定sid
    public static boolean sendInfoBySid(@PathParam("sid") String sid,String message) throws IOException {
    
    
        //log.info("推送消息到窗口"+sid+"，推送内容:"+message);
        boolean result=false;
        if(webSocketSet.size()==0){
    
    
            result=false;
        }
        for (WebSocketServer item : webSocketSet) {
    
    
            try {
    
    
              if(item.sid.equals(sid)){
    
    
                  item.sendMessage(message);
                  System.out.println("推送消息到:"+sid+"，推送内容:"+message);
                  result=true;
              }
            } catch (IOException e) {
    
    
                continue;
            }
        }
        return result;
    }


    public static synchronized int getOnlineCount() {
    
    
        return onlineCount;
    }

    public static synchronized void addOnlineCount() {
    
    
        WebSocketServer.onlineCount++;
    }

    public static synchronized void subOnlineCount() {
    
    
        WebSocketServer.onlineCount--;
    }

    @Override
    public void setEnvironment(final Environment environment) {
    
    
        this.environment = environment;
        if (globalEnvironment == null && environment != null) {
    
    
            globalEnvironment = environment;
        }
    }
}

Front-end connection sample code

<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="utf-8" />
        <meta http-equiv="X-UA-Compatible" content="IE=edge">
        <meta name="viewport" content="width=device-width, initial-scale=1">
        <title>本地websocket测试</title>
        <meta name="robots" content="all" />
        <meta name="keywords" content="本地,websocket,测试工具" />
        <meta name="description" content="本地,websocket,测试工具" />
        <style>
            .btn-group{
      
      
                display: inline-block;
            }
        </style>
    </head>
    <body>
        <input type='text' value='ws://127.0.0.1:6767/webSocket/10' class="form-control" style='width:390px;display:inline'
         id='wsaddr' />
        <div class="btn-group" >
            <button type="button" class="btn btn-default" onclick='addsocket();'>连接</button>
            <button type="button" class="btn btn-default" onclick='closesocket();'>断开</button>
            <button type="button" class="btn btn-default" onclick='$("#wsaddr").val("")'>清空</button>
        </div>
        <div class="row">
            <div id="output" style="border:1px solid #ccc;height:365px;overflow: auto;margin: 20px 0;"></div>
            <input type="text" id='message' class="form-control" style='width:810px' placeholder="待发信息" onkeydown="en(event);">
            <span class="input-group-btn">
                <button class="btn btn-default" type="button" onclick="doSend();">发送</button>
            </span>
            </div>
        </div>
        
        
    </body>     
        
        <script crossorigin="anonymous" integrity="sha384-LVoNJ6yst/aLxKvxwp6s2GAabqPczfWh6xzm38S/YtjUyZ+3aTKOnD/OJVGYLZDl" src="https://lib.baomitu.com/jquery/3.5.0/jquery.min.js"></script>
        
        
        
        
        <script language="javascript" type="text/javascript">
            function formatDate(now) {
      
      
                var year = now.getFullYear();
                var month = now.getMonth() + 1;
                var date = now.getDate();
                var hour = now.getHours();
                var minute = now.getMinutes();
                var second = now.getSeconds();
                return year + "-" + (month = month < 10 ? ("0" + month) : month) + "-" + (date = date < 10 ? ("0" + date) : date) +
                    " " + (hour = hour < 10 ? ("0" + hour) : hour) + ":" + (minute = minute < 10 ? ("0" + minute) : minute) + ":" + (
                        second = second < 10 ? ("0" + second) : second);
            }
            var output;
            var websocket;
 
            function init() {
      
      
                output = document.getElementById("output");
                testWebSocket();
            }
 
            function addsocket() {
      
      
                var wsaddr = $("#wsaddr").val();
                if (wsaddr == '') {
      
      
                    alert("请填写websocket的地址");
                    return false;
                }
                StartWebSocket(wsaddr);
            }
 
            function closesocket() {
      
      
                websocket.close();
            }
 
            function StartWebSocket(wsUri) {
      
      
                websocket = new WebSocket(wsUri);
                websocket.onopen = function(evt) {
      
      
                    onOpen(evt)
                };
                websocket.onclose = function(evt) {
      
      
                    onClose(evt)
                };
                websocket.onmessage = function(evt) {
      
      
                    onMessage(evt)
                };
                websocket.onerror = function(evt) {
      
      
                    onError(evt)
                };
            }
 
            function onOpen(evt) {
      
      
                writeToScreen("<span style='color:red'>连接成功，现在你可以发送信息啦！！！</span>");
            }
 
            function onClose(evt) {
      
      
            	 console.log('websocket 断开: ' + evt.code + ' ' + evt.reason + ' ' + evt.wasClean)
  					console.log(evt)
                writeToScreen("<span style='color:red'>websocket连接已断开!!!</span>");
                websocket.close();
            }
 
            function onMessage(evt) {
      
      
                writeToScreen('<span style="color:blue">服务端回应&nbsp;' + formatDate(new Date()) + '</span><br/><span class="bubble">' +
                    evt.data + '</span>');
            }
 
            function onError(evt) {
      
      
                writeToScreen('<span style="color: red;">发生错误:</span> ' + evt.data);
            }
 
            function doSend() {
      
      
                var message = $("#message").val();
                if (message == '') {
      
      
                    alert("请先填写发送信息");
                    $("#message").focus();
                    return false;
                }
                if (typeof websocket === "undefined") {
      
      
                    alert("websocket还没有连接，或者连接失败，请检测");
                    return false;
                }
                if (websocket.readyState == 3) {
      
      
                    alert("websocket已经关闭，请重新连接");
                    return false;
                }
                console.log(websocket);
                $("#message").val('');
                writeToScreen('<span style="color:green">你发送的信息&nbsp;' + formatDate(new Date()) + '</span><br/>' + message);
                websocket.send(message);
            }
 
            function writeToScreen(message) {
      
      
                var div = "<div class='newmessage'>" + message + "</div>";
                var d = $("#output");
                var d = d[0];
                var doScroll = d.scrollTop == d.scrollHeight - d.clientHeight;
                $("#output").append(div);
                if (doScroll) {
      
      
                    d.scrollTop = d.scrollHeight - d.clientHeight;
                }
            }
 
 
            function en(event) {
      
      
                var evt = evt ? evt : (window.event ? window.event : null);
                if (evt.keyCode == 13) {
      
      
                    doSend()
                }
            }
        </script>
 
</html>