SpringBoot：第五篇 websocket(消息推送)

1.引入jar

<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-websocket</artifactId>
    <version>4.2.9.RELEASE</version>
</dependency>

2.配置

package com.example.demo.config;

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

/**
 * @author duanxiaoqiu
 * @Date 2019-06-20 14:54
 **/
@Configuration
public class WebSocketConfig {
    @Bean
    public ServerEndpointExporter serverEndpointExporter() {
        return new ServerEndpointExporter();
    }

}

3.使用

package com.example.demo.webSocket;

import java.io.IOException;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

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

import org.springframework.stereotype.Component;
import lombok.extern.slf4j.Slf4j;

@ServerEndpoint(value = "/websocket")

@Component // 此注解千万千万不要忘记，它的主要作用就是将这个监听器纳入到Spring容器中进行管理

public class WebSocketServer {

    //统计在线人数
    private static int onlineCount = 0;


    //用本地线程保存session
    private static ThreadLocal<Session> sessions = new ThreadLocal<Session>();


    //保存所有连接上的session
    private static Map<String, Session> sessionMap = new ConcurrentHashMap<String, Session>();


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


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


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


    //连接
    @OnOpen
    public void onOpen(Session session) {
        sessions.set(session);
        addOnlineCount();
        sessionMap.put(session.getId(), session);
        System.out.println("【" + session.getId() + "】连接上服务器======当前在线人数【" + getOnlineCount() + "】");
        //连接上后给客户端一个消息
        sendMsg(session, "连接服务器成功！");
    }


    //关闭
    @OnClose
    public void onClose(Session session) {
        subOnlineCount();
        sessionMap.remove(session.getId());
        System.out.println("【" + session.getId() + "】退出了连接======当前在线人数【" + getOnlineCount() + "】");

    }


    //接收消息 客户端发送过来的消息
    @OnMessage
    public void onMessage(String message, Session session) throws InterruptedException {
        int i = 0;
        int num=1;
        while (true) {
            for (; i < 3*num; i++) {
                for (Session s : sessionMap.values()) {
                    System.out.println(i);
                    sendMsg(s, i + "");
                    Thread.sleep(3000);
                }
            }
            num++;
            if (i > 10) {
                break;
            }
        }

        //message的格式可以包含sessionid, 格式[SID,内容XXX]：1,内容
        /*System.out.println("【" + session.getId() + "】客户端的发送消息======内容【" + message + "】");
        String[] split = message.split(",");
        String sessionId = split[0];
        Session ss = sessionMap.get(sessionId);
        if (ss != null) {
            String msgTo = "【" + session.getId() + "】发送给【您】的消息:
【" + split[1] + "】";
            String msgMe = "【我】发送消息给【" + ss.getId() + "】:
" + split[1];
            sendMsg(ss, msgTo);
            sendMsg(session, msgMe);

        } else {
            for (Session s : sessionMap.values()) {
                if (!s.getId().equals(session.getId())) {
                    sendMsg(s, "【" + session.getId() + "】发送给【您】的广播消息:
【" + message + "】");
                } else {
                    sendMsg(session, "【我】发送广播消息给大家
" + message);
                }
            }
        }*/

    /*String sid = session.getId();
    Session ss = sessionMap.get(sid);*/
    }


    //异常
    @OnError
    public void onError(Session session, Throwable throwable) {
        System.out.println("发生异常!");
        throwable.printStackTrace();
    }


    //统一的发送消息方法
    public synchronized void sendMsg(Session session, String msg) {
        try {
            session.getBasicRemote().sendText(msg);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

}

4.页面

package com.example.demo.controller;

/**
 * @author duanxiaoqiu
 * @Date 2019-06-14 15:05
 **/

import com.example.demo.dao.StudentDao;
import com.example.demo.model.StudentEbo;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cache.CacheManager;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

@Slf4j
@Controller
@RequestMapping("/")
public class TestController {

    @Autowired
    private StudentDao studentDao;


    @Autowired
    private CacheManager cacheManager;


    @RequestMapping("/")
    @ResponseBody
    public String index() {
        return studentDao.getStuById(1L).getName();
    }

    @RequestMapping("/websocket")
    public String init() {
        return "index.html";
    }

}

<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>My WebSocket Test</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WebSocket
    if('WebSocket' in window){
        websocket = new WebSocket("ws://localhost:8080/websocket");
    }
    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>