QQ這類即時(shí)通訊工具多數(shù)是以桌面應(yīng)用的方式存在。在沒(méi)有websocket出現(xiàn)之前,如果開(kāi)發(fā)一個(gè)網(wǎng)頁(yè)版的即時(shí)通訊應(yīng)用,則需要定時(shí)刷新頁(yè)面或定時(shí)調(diào)用ajax請(qǐng)求,這無(wú)疑會(huì)加大服務(wù)器的負(fù)載和增加了客戶端的流量。而websocket的出現(xiàn),則完美的解決了這些問(wèn)題。
spring boot對(duì)websocket進(jìn)行了封裝,這對(duì)實(shí)現(xiàn)一個(gè)websocket網(wǎng)頁(yè)即時(shí)通訊應(yīng)用來(lái)說(shuō),變得非常簡(jiǎn)單。
一、準(zhǔn)備工作
pom.xml引入
<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-websocket</artifactId></dependency>
完整的pom.xml文件代碼如下:
pom.xml
二、代碼編寫(xiě)
1.創(chuàng)建名為“WebSocketConfig.java”的類來(lái)配置websocket,并繼承抽象類“AbstractWebSocketMessageBrokerConfigurer”
此類聲明“@EnableWebSocketMessageBroker”的注解
package com.example;import org.springframework.context.annotation.Configuration;import org.springframework.messaging.simp.config.MessageBrokerRegistry;import org.springframework.web.socket.config.annotation.AbstractWebSocketMessageBrokerConfigurer;import org.springframework.web.socket.config.annotation.EnableWebSocketMessageBroker;import org.springframework.web.socket.config.annotation.StompEndpointRegistry; @Configuration @EnableWebSocketMessageBrokerpublic class WebSocketConfig extends AbstractWebSocketMessageBrokerConfigurer { @Override public void configureMessageBroker(MessageBrokerRegistry config) { config.enableSimpleBroker("/topic"); config.setApplicationDestinationPrefixes("/app"); } @Override public void registerStompEndpoints(StompEndpointRegistry registry) { registry.addEndpoint("/my-websocket").withSockJS(); } }
這里配置了以“/app”開(kāi)頭的websocket請(qǐng)求url。和名為“my-websocket”的endpoint(端點(diǎn))
2.編寫(xiě)一個(gè)DTO類來(lái)承載消息:
package com.example;public class SocketMessage { public String message; public String date; }
3.創(chuàng)建App.java類,用于啟用spring boot和用于接收、發(fā)送消息的控制器。
package com.example;import java.text.DateFormat;import java.text.SimpleDateFormat;import java.util.Date;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;import org.springframework.messaging.handler.annotation.MessageMapping;import org.springframework.messaging.handler.annotation.SendTo;import org.springframework.messaging.simp.SimpMessagingTemplate;import org.springframework.scheduling.annotation.EnableScheduling;import org.springframework.scheduling.annotation.Scheduled;import org.springframework.stereotype.Controller;import org.springframework.web.bind.annotation.GetMapping; @Controller @EnableScheduling @SpringBootApplicationpublic class App { public static void main(String[] args) { SpringApplication.run(App.class, args); } @Autowired private SimpMessagingTemplate messagingTemplate; @GetMapping("/") public String index() { return "index"; } @MessageMapping("/send") @SendTo("/topic/send") public SocketMessage send(SocketMessage message) throws Exception { DateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); message.date = df.format(new Date()); return message; } @Scheduled(fixedRate = 1000) @SendTo("/topic/callback") public Object callback() throws Exception { // 發(fā)現(xiàn)消息 DateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); messagingTemplate.convertAndSend("/topic/callback", df.format(new Date())); return "callback"; } }
“send”方法用于接收客戶端發(fā)送過(guò)來(lái)的websocket請(qǐng)求。
@EnableScheduling注解為:啟用spring boot的定時(shí)任務(wù),這與“callback”方法相呼應(yīng),用于每隔1秒推送服務(wù)器端的時(shí)間。
4.在“resources/templates”目錄下創(chuàng)建index.html文件:
<!DOCTYPE html><html><head><title>玩轉(zhuǎn)spring boot——websocket</title><script src="//cdn.bootcss.com/angular.js/1.5.6/angular.min.js"></script><script src="https://cdn.bootcss.com/sockjs-client/1.1.4/sockjs.min.js"></script><script src="https://cdn.bootcss.com/stomp.js/2.3.3/stomp.min.js"></script><script type="text/javascript"> /*<![CDATA[*/ var stompClient = null; var app = angular.module('app', []); app.controller('MainController', function($rootScope, $scope, $http) { $scope.data = { //連接狀態(tài) connected : false, //消息 message : '', rows : [] }; //連接 $scope.connect = function() { var socket = new SockJS('/my-websocket'); stompClient = Stomp.over(socket); stompClient.connect({}, function(frame) { // 注冊(cè)發(fā)送消息 stompClient.subscribe('/topic/send', function(msg) { $scope.data.rows.push(JSON.parse(msg.body)); $scope.data.connected = true; $scope.$apply(); }); // 注冊(cè)推送時(shí)間回調(diào) stompClient.subscribe('/topic/callback', function(r) { $scope.data.time = '當(dāng)前服務(wù)器時(shí)間:' + r.body; $scope.data.connected = true; $scope.$apply(); }); $scope.data.connected = true; $scope.$apply(); }); }; $scope.disconnect = function() { if (stompClient != null) { stompClient.disconnect(); } $scope.data.connected = false; } $scope.send = function() { stompClient.send("/app/send", {}, JSON.stringify({ 'message' : $scope.data.message })); } }); /*]]>*/</script></head><body ng-app="app" ng-controller="MainController"> <h2>玩轉(zhuǎn)spring boot——websocket</h2> <h4> 出處:劉冬博客 <a href="http://www.cnblogs.com/goodhelper">http://www.cnblogs.com/goodhelper</a> </h4> <label>WebSocket連接狀態(tài):</label> <button type="button" ng-disabled="data.connected" ng-click="connect()">連接</button> <button type="button" ng-click="disconnect()" ng-disabled="!data.connected">斷開(kāi)</button> <br /> <br /> <div ng-show="data.connected"> <label>{{data.time}}</label> <br /> <br /> <input type="text" ng-model="data.message" placeholder="請(qǐng)輸入內(nèi)容..." /> <button ng-click="send()" type="button">發(fā)送</button> <br /> <br /> 消息列表: <br /> <table> <thead> <tr> <th>內(nèi)容</th> <th>時(shí)間</th> </tr> </thead> <tbody> <tr ng-repeat="row in data.rows"> <td>{{row.message}}</td> <td>{{row.date}}</td> </tr> </tbody> </table> </div></body></html>
除了引用angular.js的CDN文件外,還需要引用sockjs和stomp。
完整的項(xiàng)目結(jié)構(gòu),如下圖所示:
三、運(yùn)行效果
點(diǎn)擊“連接”按鈕,出現(xiàn)發(fā)送消息的輸入框。并接收到服務(wù)器端的時(shí)間推送。
輸入發(fā)送內(nèi)容并點(diǎn)擊“發(fā)送”按鈕后,頁(yè)面顯示出剛才發(fā)送的消息。
點(diǎn)擊“斷開(kāi)”按鈕,則服務(wù)器端不會(huì)再推送消息。
總結(jié)
在開(kāi)發(fā)一個(gè)基于web的即時(shí)通訊應(yīng)用的過(guò)程中,我們還需考慮session的機(jī)制。
還需要一個(gè)集合來(lái)承載當(dāng)前的在線用戶,并做一個(gè)定時(shí)任務(wù),其目的是用輪詢的方式定時(shí)處理在線用戶的狀態(tài),有哪些用戶在線,又有哪些用戶離線。
參考:
http://spring.io/guides/gs/scheduling-tasks/
http://spring.io/guides/gs/messaging-stomp-websocket/
代碼地址:
https://github.com/carter659/spring-boot-16
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