SpringBoot集成WebSocket，實(shí)現(xiàn)后臺(tái)向前端推送信息
前言
在一次項(xiàng)目開(kāi)發(fā)中，使用到了Netty網(wǎng)絡(luò)應(yīng)用框架，以及MQTT進(jìn)行消息數(shù)據(jù)的收發(fā)，這其中需要后臺(tái)來(lái)將獲取到的消息主動(dòng)推送給前端，于是就使用到了MQTT，特此記錄一下。
一、什么是websocket？
WebSocket協(xié)議是基于TCP的一種新的網(wǎng)絡(luò)協(xié)議。它實(shí)現(xiàn)了客戶端與服務(wù)器全雙工通信，學(xué)過(guò)計(jì)算機(jī)網(wǎng)絡(luò)都知道，既然是全雙工，就說(shuō)明了服務(wù)器可以主動(dòng)發(fā)送信息給客戶端。這與我們的推送技術(shù)或者是多人在線聊天的功能不謀而合。
百度網(wǎng)盤(pán)再次回收免費(fèi)空間！21日前趕緊登錄下！網(wǎng)友評(píng)：想錢(qián)想瘋了？
為什么不使用HTTP 協(xié)議呢？這是因?yàn)镠TTP是單工通信，通信只能由客戶端發(fā)起，客戶端請(qǐng)求一下，服務(wù)器處理一下，這就太麻煩了。于是websocket應(yīng)運(yùn)而生。
從 HTTP 到 HTTP/3 的發(fā)展簡(jiǎn)史
下面我們就直接開(kāi)始使用Springboot開(kāi)始整合。以下案例都在我自己的電腦上測(cè)試成功，你可以根據(jù)自己的功能進(jìn)行修改即可。我的項(xiàng)目結(jié)構(gòu)如下：
二、使用步驟
1.添加依賴
Maven依賴：
?<dependency>??
???????????<groupId>org.springframework.bootgroupId>??
???????????<artifactId>spring-boot-starter-websocketartifactId>??
????dependency>?
2.啟用Springboot對(duì)WebSocket的支持
啟用WebSocket的支持也是很簡(jiǎn)單，幾句代碼搞定：
import?org.springframework.context.annotation.Bean;
import?org.springframework.context.annotation.Configuration;
import?org.springframework.web.socket.server.standard.ServerEndpointExporter;
/**
?*?@?Auther:?馬超偉
?*?@?Date:?2020/06/16/14:35
?*?@?Description:?開(kāi)啟WebSocket支持
?*/
@Configuration
public?class?WebSocketConfig?{
????@Bean
????public?ServerEndpointExporter?serverEndpointExporter()?{
????????return?new?ServerEndpointExporter();
????}
}
3.核心配置：WebSocketServer
因?yàn)閃ebSocket是類似客戶端服務(wù)端的形式(采用ws協(xié)議)，那么這里的WebSocketServer其實(shí)就相當(dāng)于一個(gè)ws協(xié)議的Controller
@ ServerEndpoint 注解是一個(gè)類層次的注解，它的功能主要是將目前的類定義成一個(gè)websocket服務(wù)器端, 注解的值將被用于監(jiān)聽(tīng)用戶連接的終端訪問(wèn)URL地址,客戶端可以通過(guò)這個(gè)URL來(lái)連接到WebSocket服務(wù)器端 新建一個(gè)ConcurrentHashMap webSocketMap 用于接收當(dāng)前userId的WebSocket，方便傳遞之間對(duì)userId進(jìn)行推送消息。
下面是具體業(yè)務(wù)代碼：
package?cc.mrbird.febs.external.webScoket;
import?com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import?com.baomidou.mybatisplus.core.conditions.update.UpdateWrapper;
import?lombok.extern.slf4j.Slf4j;
import?org.springframework.stereotype.Component;
import?org.springframework.stereotype.Service;
import?javax.websocket.*;
import?javax.websocket.server.PathParam;
import?javax.websocket.server.ServerEndpoint;
import?java.io.IOException;
import?java.time.LocalDateTime;
import?java.util.List;
import?java.util.concurrent.CopyOnWriteArraySet;
/**
?*?Created?with?IntelliJ?IDEA.
?*?@?Auther:?馬超偉
?*?@?Date:?2020/06/16/14:35
?*?@?Description:
?*?@?ServerEndpoint?注解是一個(gè)類層次的注解，它的功能主要是將目前的類定義成一個(gè)websocket服務(wù)器端,
?*?注解的值將被用于監(jiān)聽(tīng)用戶連接的終端訪問(wèn)URL地址,客戶端可以通過(guò)這個(gè)URL來(lái)連接到WebSocket服務(wù)器端
?*/
@Component
@Slf4j
@Service
@ServerEndpoint("/api/websocket/{sid}")
public?class?WebSocketServer?{
????//靜態(tài)變量，用來(lái)記錄當(dāng)前在線連接數(shù)。應(yīng)該把它設(shè)計(jì)成線程安全的。
????private?static?int?onlineCount?=?0;
????//concurrent包的線程安全Set，用來(lái)存放每個(gè)客戶端對(duì)應(yīng)的MyWebSocket對(duì)象。
????private?static?CopyOnWriteArraySet?webSocketSet?=?new?CopyOnWriteArraySet();
????//與某個(gè)客戶端的連接會(huì)話，需要通過(guò)它來(lái)給客戶端發(fā)送數(shù)據(jù)
????private?Session?session;
????//接收sid
????private?String?sid?=?"";
????/**
?????*?連接建立成功調(diào)用的方法
?????*/
????@OnOpen
????public?void?onOpen(Session?session,?@PathParam("sid")?String?sid)?{
????????this.session?=?session;
????????webSocketSet.add(this);?????//加入set中
????????this.sid?=?sid;
????????addOnlineCount();???????????//在線數(shù)加1
????????try?{
????????????sendMessage("conn_success");
????????????log.info("有新窗口開(kāi)始監(jiān)聽(tīng):"?+?sid?+?",當(dāng)前在線人數(shù)為:"?+?getOnlineCount());
????????}?catch?(IOException?e)?{
????????????log.error("websocket?IO?Exception");
????????}
????}
????/**
?????*?連接關(guān)閉調(diào)用的方法
?????*/
????@OnClose
????public?void?onClose()?{
????????webSocketSet.remove(this);??//從set中刪除
????????subOnlineCount();???????????//在線數(shù)減1
????????//斷開(kāi)連接情況下，更新主板占用情況為釋放
????????log.info("釋放的sid為："+sid);
????????//這里寫(xiě)你?釋放的時(shí)候，要處理的業(yè)務(wù)
????????log.info("有一連接關(guān)閉！當(dāng)前在線人數(shù)為"?+?getOnlineCount());
????}
????/**
?????*?收到客戶端消息后調(diào)用的方法
?????*?@?Param?message?客戶端發(fā)送過(guò)來(lái)的消息
?????*/
????@OnMessage
????public?void?onMessage(String?message,?Session?session)?{
????????log.info("收到來(lái)自窗口"?+?sid?+?"的信息:"?+?message);
????????//群發(fā)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("發(fā)生錯(cuò)誤");
????????error.printStackTrace();
????}
????/**
?????*?實(shí)現(xiàn)服務(wù)器主動(dòng)推送
?????*/
????public?void?sendMessage(String?message)?throws?IOException?{
????????this.session.getBasicRemote().sendText(message);
????}
????/**
?????*?群發(fā)自定義消息
?????*/
????public?static?void?sendInfo(String?message,?@PathParam("sid")?String?sid)?throws?IOException?{
????????log.info("推送消息到窗口"?+?sid?+?"，推送內(nèi)容:"?+?message);
????????for?(WebSocketServer?item?:?webSocketSet)?{
????????????try?{
????????????????//這里可以設(shè)定只推送給這個(gè)sid的，為null則全部推送
????????????????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--;
????}
????public?static?CopyOnWriteArraySet?getWebSocketSet()? {
????????return?webSocketSet;
????}
}
4.測(cè)試Controller
import?org.springframework.stereotype.Controller;
import?org.springframework.web.bind.annotation.GetMapping;
import?org.springframework.web.bind.annotation.PathVariable;
import?org.springframework.web.bind.annotation.RequestMapping;
import?org.springframework.web.bind.annotation.ResponseBody;
import?org.springframework.web.servlet.ModelAndView;
import?java.io.IOException;
import?java.util.HashMap;
import?java.util.Map;
/**
?*?Created?with?IntelliJ?IDEA.
?*
?*?@?Auther:?馬超偉
?*?@?Date:?2020/06/16/14:38
?*?@?Description:
?*/
@Controller("web_Scoket_system")
@RequestMapping("/api/socket")
public?class?SystemController?{
????//頁(yè)面請(qǐng)求
????@GetMapping("/index/{userId}")
????public?ModelAndView?socket(@PathVariable?String?userId)?{
????????ModelAndView?mav?=?new?ModelAndView("/socket1");
????????mav.addObject("userId",?userId);
????????return?mav;
????}
????//推送數(shù)據(jù)接口
????@ResponseBody
????@RequestMapping("/socket/push/{cid}")
????public?Map?pushToWeb(@PathVariable?String?cid,?String?message)?{
????????Map?result?=?new?HashMap<>();
????????try?{
????????????WebSocketServer.sendInfo(message,?cid);
????????????result.put("code",?cid);
????????????result.put("msg",?message);
????????}?catch?(IOException?e)?{
????????????e.printStackTrace();
????????}
????????return?result;
????}
}
5.測(cè)試頁(yè)面index.html
html>
<html>
?<head>
??<meta?charset="utf-8">
??<title>Java后端WebSocket的Tomcat實(shí)現(xiàn)title>
??<script?type="text/javascript"?src="js/jquery.min.js">script>
?head>
?<body>
??<div?id="main"?style="width:?1200px;height:800px;">div>
??Welcome<br/><input?id="text"?type="text"?/>
??<button?onclick="send()">發(fā)送消息button>
??<hr/>
??<button?onclick="closeWebSocket()">關(guān)閉WebSocket連接button>
??<hr/>
??<div?id="message">div>
?body>
?<script?type="text/javascript">
??var?websocket?=?null;
??//判斷當(dāng)前瀏覽器是否支持WebSocket
??if('WebSocket'?in?window)?{
???//改成你的地址
???websocket?=?new?WebSocket("ws://192.168.100.196:8082/api/websocket/100");
??}?else?{
???alert('當(dāng)前瀏覽器?Not?support?websocket')
??}
??//連接發(fā)生錯(cuò)誤的回調(diào)方法
??websocket.onerror?=?function()?{
???setMessageInnerHTML("WebSocket連接發(fā)生錯(cuò)誤");
??};
??//連接成功建立的回調(diào)方法
??websocket.onopen?=?function()?{
???setMessageInnerHTML("WebSocket連接成功");
??}
??var?U01data,?Uidata,?Usdata
??//接收到消息的回調(diào)方法
??websocket.onmessage?=?function(event)?{
???console.log(event);
???setMessageInnerHTML(event);
???setechart()
??}
??//連接關(guān)閉的回調(diào)方法
??websocket.onclose?=?function()?{
???setMessageInnerHTML("WebSocket連接關(guān)閉");
??}
??//監(jiān)聽(tīng)窗口關(guān)閉事件，當(dāng)窗口關(guān)閉時(shí)，主動(dòng)去關(guān)閉websocket連接，防止連接還沒(méi)斷開(kāi)就關(guān)閉窗口，server端會(huì)拋異常。
??window.onbeforeunload?=?function()?{
???closeWebSocket();
??}
??//將消息顯示在網(wǎng)頁(yè)上
??function?setMessageInnerHTML(innerHTML)?{
???document.getElementById('message').innerHTML?+=?innerHTML?+?'
';
??}
??//關(guān)閉WebSocket連接
??function?closeWebSocket()?{
???websocket.close();
??}
??//發(fā)送消息
??function?send()?{
???var?message?=?document.getElementById('text').value;
???websocket.send('{"msg":"'?+?message?+?'"}');
???setMessageInnerHTML(message?+?"
");
??}
?script>
html>
6.結(jié)果展示
后臺(tái)：如果有連接請(qǐng)求
他總在逆風(fēng)翻盤(pán)，絕地反擊！最不愛(ài)錢(qián)卻成了最有錢(qián)的人...
前臺(tái)顯示：
開(kāi)發(fā)文件上傳功能稍不注意就會(huì)引發(fā)安全漏洞
總結(jié)
這中間我遇到一個(gè)問(wèn)題，就是說(shuō)WebSocket啟動(dòng)的時(shí)候優(yōu)先于spring容器，從而導(dǎo)致在WebSocketServer中調(diào)用業(yè)務(wù)Service會(huì)報(bào)空指針異常
所以需要在WebSocketServer中將所需要用到的service給靜態(tài)初始化一下：如圖所示：
還需要做如下配置：
來(lái)源：https://blog.csdn.net/MacWx/article/details/111319558
版權(quán)申明：內(nèi)容來(lái)源網(wǎng)絡(luò)，版權(quán)歸原創(chuàng)者所有。除非無(wú)法確認(rèn)，我們都會(huì)標(biāo)明作者及出處，如有侵權(quán)煩請(qǐng)告知，我們會(huì)立即刪除并表示歉意。謝謝!
評(píng)論
圖片
表情