spring boot 集成webSocket

介绍

前后端分离项目中前端大多使用ajax调用服务器接口，但是如果要实现消息提醒功能该如何实现消息推送

webSocket的做法是发送一个持久性的请求，并进行双向数据传输。

第一步导入依赖


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

<!--Lombok能通过注解的方式，在编译时自动为属性生成构造器、getter/setter、equals、hashcode、toString方法。-->
 <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.8</version>
            <scope>provided</scope>
</dependency>

第二步 webSocket服务


    import lombok.extern.slf4j.Slf4j;
    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.ServerEndpoint;
    import java.io.IOException;
    import java.util.concurrent.CopyOnWriteArraySet;
    
    @Slf4j
    @ServerEndpoint(value = "/websocket")
    @Component
    public class WebSocketServer
    {
    
        //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;
    
        /**
         * 连接建立成功调用的方法
         */
        @OnOpen
        public void onOpen(Session session)
        {
            this.session = session;
            webSocketSet.add(this);     //加入set中
            addOnlineCount();           //在线数加1
            log.info("有新连接加入！当前在线人数为" + getOnlineCount());
            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
         *
         * @param message 客户端发送过来的消息
         */
        @OnMessage
        public void onMessage(String message, Session session)
        {
            log.info("来自客户端的消息:" + message);
    
            //群发消息
            for (WebSocketServer item : webSocketSet)
            {
                try
                {
                    item.sendMessage(message);
                }
                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();
        }
    
    
        public void sendMessage(String message) throws IOException
        {
            this.session.getBasicRemote().sendText(message);
        }
    
    
        /**
         * 群发自定义消息
         */
        public static void sendInfo(String message) throws IOException
        {
            log.info(message);
            for (WebSocketServer item : webSocketSet)
            {
                try
                {
                    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--;
        }
    
    }

第三步配置


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

@Configuration
public class WebSocketConfig
{
    @Bean
    public ServerEndpointExporter serverEndpointExporter()
    {
        return new ServerEndpointExporter();
    }

}

第四步写Controller


package com.hc.demo.controller;

import com.hc.demo.service.WebSocketServer;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;

import java.io.IOException;
import java.util.HashMap;
import java.util.Map;

@Controller
public class WebSocketController
{


    @RequestMapping(value = "/pushVideoListToWeb", method = RequestMethod.POST, consumes = "application/json")
    public @ResponseBody
    Map<String, Object> pushVideoListToWeb(@RequestBody Map<String, Object> param)
    {
        Map<String, Object> result = new HashMap<String, Object>();

        try
        {
            WebSocketServer.sendInfo("有新客户呼入");
            result.put("operationResult", true);
        }
        catch (IOException e)
        {
            result.put("operationResult", true);
        }
        return result;
    }
}

第五步前端调用


<!DOCTYPE HTML>
<html>
<head>
    <title>My 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WebSocket
    if('WebSocket' in window){
        websocket = new WebSocket("ws://localhost:9898/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>

好了就这样可以试一试效果