pom添加：
<!-- websocket--><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-websocket</artifactId></dependency>socket服务实现
import com.alibaba.fastjson.JSON;
import com.hdtd.safequalitycollect.common.utils.DateFormatterUtils;
import lombok.extern.slf4j.Slf4j;
import org.apache.commons.lang3.ObjectUtils;
import org.springframework.stereotype.Component;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 java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.Set;
import java.util.concurrent.CopyOnWriteArraySet;
import java.util.stream.Collectors;@Slf4j
@ServerEndpoint("/earlyWarning/{sid}")
@Component
public class EarlyWarningWebsocketServer {/*** 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 final CopyOnWriteArraySet<EarlyWarningWebsocketServer> webSocketSet = new CopyOnWriteArraySet<>();/*** 忽略预警消息列表* key:用户id+时间戳,value:预警类型*/private static final HashMap<String,String> warningIgnoreList = new HashMap<>();/*** 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;/*** 设置websocket超时时间*/public static final long MAX_TIME_OUT = 50L * 60L * 1000L;/*** 接收sid*/private String sid = "";/*** 连接建立成功调用的方法*/@OnOpenpublic void onOpen(Session session, @PathParam("sid") String sid) {this.session = session;session.setMaxIdleTimeout(MAX_TIME_OUT);//如果存在就先删除一个，防止重复推送消息for (EarlyWarningWebsocketServer webSocket : webSocketSet) {if (webSocket.sid.equals(sid)) {webSocketSet.remove(webSocket);}}this.sid = sid;webSocketSet.add(this);}/*** 连接关闭调用的方法*/@OnClosepublic void onClose() {webSocketSet.remove(this);}/*** 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*/@OnMessagepublic void onMessage(String message, Session session) {log.info("收到来自" + sid + "的信息:" + message);//群发消息
// String yyMmDdHh = DateFormatterUtils.getYyMmDdHh();
// if(ObjectUtils.isEmpty(warningIgnoreList.get(sid + yyMmDdHh))){
// // 清空warningIgnoreList中，key包含 sid 的，并且预警类型与message相同的记录
// Iterator<String> iterator = warningIgnoreList.keySet().iterator();
// while (iterator.hasNext()) {
// String key = iterator.next();
// if (key.contains(sid) && Objects.equals(warningIgnoreList.get(key), message)) {
// iterator.remove();
// }
// }
// warningIgnoreList.put(sid + yyMmDdHh, message);
// }}@OnErrorpublic void onError(Session session, Throwable error) {log.error(session.getId() + "发生错误");error.printStackTrace();}/*** 实现服务器主动推送*/public void sendMessage(String message) throws IOException {synchronized (session) {this.session.getBasicRemote().sendText(message);log.info("推送消息到" + sid + "成功，消息为：" + message);}}/*** 群发自定义消息*/public static void sendInfo(String message) {for (EarlyWarningWebsocketServer productWebSocket : webSocketSet) {try {productWebSocket.sendMessage(message);log.info("推送消息给全体用户" + "成功，消息为：" + message);} catch (Exception e) {log.error("推送消息失败：{}", e.getMessage());}}}/*** 给指定连接用户自定义消息*/public static void sendInfo(SocketMsg socketMsg, @PathParam("sid") String sid) throws IOException {String message = JSON.toJSONString(socketMsg);log.info("推送消息到" + sid + "，推送内容:" + message);for (EarlyWarningWebsocketServer 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.sid.equals(sid)) {item.sendMessage(message);}} catch (IOException ignored) {log.error("消息推送失败：{}", ignored.getMessage());}}}/*** 给特定客户端发送信息*/public static void sendInfo(String message, String sid) throws IOException {log.info("推送消息到" + sid + "，推送内容:" + message);for (EarlyWarningWebsocketServer 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.sid.equals(sid)) {item.sendMessage(message);}} catch (IOException ignored) {log.error("消息推送失败：{}", ignored.getMessage());}}}@Overridepublic boolean equals(Object o) {if (this == o) {return true;}if (o == null || getClass() != o.getClass()) {return false;}EarlyWarningWebsocketServer that = (EarlyWarningWebsocketServer) o;return Objects.equals(session, that.session) &&Objects.equals(sid, that.sid);}@Overridepublic int hashCode() {return Objects.hash(session, sid);}}
项目启动后，socket服务自动启动
前端案例：
<!DOCTYPE HTML>
<html>
<head><title>WebSocket</title>
</head><body>
Welcome<br/>
<input id="text" type="text" />
<button onclick="send()">Send</button>
<button onclick="closeWebSocket()">Close</button>
<div id="message">
</div>
</body><script type="text/javascript">var websocket = null;//判断当前浏览器是否支持WebSocketif('WebSocket' in window){websocket = new WebSocket("ws://XXX:8080/earlyWarning/2");}else{alert('Not support websocket')}//连接发生错误的回调方法websocket.onerror = function(){setMessageInnerHTML("error");};//连接成功建立的回调方法websocket.onopen = function(event){setMessageInnerHTML("open");}//接收到消息的回调方法websocket.onmessage = function(event){setMessageInnerHTML(event.data);}//连接关闭的回调方法websocket.onclose = function(){setMessageInnerHTML("close");}//监听窗口关闭事件，当窗口关闭时，主动去关闭websocket连接，防止连接还没断开就关闭窗口，server端会抛异常。window.onbeforeunload = function(){websocket.close();}//将消息显示在网页上function setMessageInnerHTML(innerHTML){document.getElementById('message').innerHTML += innerHTML + '<br/>';}//关闭连接function closeWebSocket(){websocket.close();}//发送消息function send(){var message = document.getElementById('text').value;websocket.send(message);}
</script>
</html>实现效果：
后台发送消息到前端，前端页面进行处理，前端也可以发送对应信息给后台，后台处理。
注意：socket连接时，需要前端提供对应的用户id，对用户进行区分，可以实现单个用户的发送接收。