WebSocketServer的使用(@ServerEndpoint)

前端代码

	function initWebSocket() {
        if (typeof WebSocket == "undefined") {
          console.log("您的浏览器不支持WebSocket");
        } else {
          console.log("您的浏览器支持WebSocket");
          //实现化WebSocket对象，指定要连接的服务器地址与端口 建立连接
          //等同于socket = new WebSocket("ws://localhost:8083/checkcentersys/websocket/20");
          var wsPathStr = wsPath + uuid;
          console.log("uuid22:" + uuid);
          socket = new WebSocket(wsPathStr);
          //打开事件
          socket.onopen = function () {
            console.log("Socket 已打开");
            socket.send("这是来自客户端的消息" + location.href + new Date());
          };

          //获得消息事件
          socket.onmessage = function (msg) {
            // debugger;
            console.log(msg.data);
            var data = JSON.parse(msg.data);
            if (data.code == 200) {
              alert("登录成功！");
              //这里存放自己业务需要的数据。怎么放自己看
              window.sessionStorage.uuid = uuid;
              window.sessionStorage.userId = data.userId;
              window.sessionStorage.projId = data.projId;

              window.location.href = "pages/upload.html";
            } else {
              //如果过期了，关闭连接、重置连接、刷新二维码
              // socket.close();
              // initQrImg();
              debugger;
              let path2 = getQrPath2 + "/" + uuid;
              axios
                .get(path2, {
                  params: { dd: "cc" },
                })
                .then(
                  function (success) {
                    console.log("成功");
                  },
                  function (fail) {
                    console.log("失败");
                  }
                )
                .catch(function (error) {
                  console.log("异常");
                });
            }

            //发现消息进入 开始处理前端触发逻辑
          };
          //关闭事件
          socket.onclose = function () {
            console.log("Socket已关闭");
          };
          //发生了错误事件
          socket.onerror = function () {
            alert("Socket发生了错误");
            //此时可以尝试刷新页面
          };
        }

后端Java代码

package com.example.poi.utils;

import cn.hutool.json.JSONObject;
import cn.hutool.log.Log;
import cn.hutool.log.LogFactory;
import org.springframework.context.annotation.Bean;
import org.springframework.stereotype.Component;
import org.springframework.web.socket.server.standard.ServerEndpointExporter;

import javax.websocket.*;
import javax.websocket.server.PathParam;
import javax.websocket.server.ServerEndpoint;
import java.io.IOException;
import java.util.concurrent.CopyOnWriteArraySet;

/**
 * @Author xu
 * @create 2023/7/21 19
 */
@ServerEndpoint("/websocket/{sid}")
@Component
public class WebSocketServer {
    static Log log= LogFactory.get(WebSocketServer.class);

    //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。
    private static CopyOnWriteArraySet<WebSocketServer> webSocketSet = new CopyOnWriteArraySet<WebSocketServer>();

    //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;

    //接收sid
    private String sid="";

    /**
     * 连接建立成功调用的方法
     *
     * @param session
     * @param sid
     */
    @OnOpen
    public void onOpen(Session session,@PathParam("sid") String sid) {
        this.session = session;
        webSocketSet.add(this); //加入set中
        addOnlineCount(); //在线数加1
        log.info("有新窗口开始监听:"+sid+",当前在线人数为" + getOnlineCount());
        this.sid=sid;
        /*try {
            sendMessage("连接成功");
        } catch (IOException e) {
            log.error("websocket IO异常");
        }*/
    }

    /**
     * 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
        log.info("有一连接关闭！当前在线人数为" + getOnlineCount());
    }

    /**
     *  收到客户端消息后调用的方法
     * 客户端发送过来的消息
     * @param message
     * @param session
     */
    @OnMessage
    public void onMessage(String message, Session session) {
        log.info("收到来自窗口"+sid+"的信息:"+message);
        //群发消息
        for (WebSocketServer item : webSocketSet) {
            try {
                JSONObject jsonObject = new JSONObject();
                jsonObject.put("name","张三");
                jsonObject.put("code",2001);
                jsonObject.put("userId",16);
                jsonObject.put("projId",200);
                item.sendMessage(jsonObject.toString());
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    /**
     *
     * @param session
     * @param error
     */
    @OnError
    public void onError(Session session, Throwable error) {
        log.error("发生错误");
        error.printStackTrace();
    }

    /**
     * 实现服务器主动推送
     * @param message
     * @throws IOException
     */
    public void sendMessage(String message) throws IOException {
        this.session.getBasicRemote().sendText(message);
    }


    /**
     * 发送消息
     * @param message
     * @param sid
     * @throws IOException
     */
    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);
        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) {
                    item.sendMessage(message);
                }else if(item.sid.equals(sid)){
                    item.sendMessage(message);
                }
            } catch (IOException e) {
                continue;
            }
        }
    }

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

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

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


    /**必须要有这个bean才能生效使用webSocketServer*/
    @Bean
    public ServerEndpointExporter serverEndpointExporter() {
        return new ServerEndpointExporter();
    }

}

pom

		<dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.5.1</version>
        </dependency>


        <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>8.0.13</version>
        </dependency>

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

        <dependency>
            <groupId>cn.hutool</groupId>
            <artifactId>hutool-all</artifactId>
            <version>5.7.10</version>
        </dependency>

        <dependency>
            <groupId>com.google.zxing</groupId>
            <artifactId>core</artifactId>
            <version>3.4.1</version>
        </dependency>

        <dependency>
            <groupId>commons-lang</groupId>
            <artifactId>commons-lang</artifactId>
            <version>2.6</version>
        </dependency>

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


        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.12</version>
        </dependency>

生成二维码

   //获取登录二维码、放入Token
    //@CrossOrigin
    @RequestMapping(value = "/getLoginQr" ,method = RequestMethod.GET)
    public void createCodeImg(HttpServletRequest request, HttpServletResponse response){
        response.setHeader("Pragma", "No-cache");
        response.setHeader("Cache-Control", "no-cache");

        response.setDateHeader("Expires", 0);
        response.setContentType("image/jpeg");

        try {

            //这里没啥操作 就是生成一个UUID插入 数据库的表里
            //String uuid = userService.createQrImg();
            String uuid = "jdhasndi452iiwn11";
            response.addHeader("uuid", uuid);
            response.addHeader("Access-Control-Expose-Headers", "uuid");
            response.addHeader("Access-Control-Allow-Origin", "*");
            // 这里是开源工具类 hutool里的QrCodeUtil
            // 网址：http://hutool.mydoc.io/
            QrCodeUtil.generate(uuid, 300, 300, "jpg",response.getOutputStream());
            System.out.println("**");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

扫码前端

<div id="qrImgDiv"></div>

function initQrImg() {
        $("#qrImgDiv").empty();

        var xmlhttp;
        xmlhttp = new XMLHttpRequest();
        xmlhttp.open("GET", getQrPath, true);
        xmlhttp.responseType = "blob";
        xmlhttp.onload = function () {
          console.log(this);
          uuid = this.getResponseHeader("uuid");
          console.log("uuid=", uuid);

          if (this.status == 200) {
            var blob = this.response;
            var img = document.createElement("img");
            img.className = "qrCodeBox-img";
            img.onload = function (e) {
              window.URL.revokeObjectURL(img.src);
            };
            img.src = window.URL.createObjectURL(blob);
            document.getElementById("qrImgDiv").appendChild(img);
          }
        };
        xmlhttp.send();
      }