前言
QQ这类即时通讯工具多数是以桌面应用的方式存在。在没有websocket出现之前，如果开发一个网页版的即时通讯应用，则需要定时刷新页面或定时调用ajax请求，这无疑会加大服务器的负载和增加了客户端的流量。而websocket的出现，则完美的解决了这些问题。
spring boot对websocket进行了封装，这对实现一个websocket网页即时通讯应用来说，变得非常简单。
一、准备工作
pom.xml引入
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<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-websocket</artifactId></dependency> |
完整的pom.xml文件代码如下：
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<?xml version="1.0" encoding="UTF-8"?><project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.example</groupId> <artifactId>spring-boot-16</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>jar</packaging> <name>spring-boot-16</name> <description>Demo project for Spring Boot</description> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>1.5.3.RELEASE</version> <relativePath /> <!-- lookup parent from repository --> </parent> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding> <java.version>1.8</java.version> </properties> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-thymeleaf</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-websocket</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-devtools</artifactId> <scope>runtime</scope> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build></project> |
二、代码编写
1.创建名为“WebSocketConfig.java”的类来配置websocket，并继承抽象类“AbstractWebSocketMessageBrokerConfigurer”
此类声明“@EnableWebSocketMessageBroker”的注解
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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(); }} |
这里配置了以“/app”开头的websocket请求url。和名为“my-websocket”的endpoint(端点)
2.编写一个DTO类来承载消息：
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package com.example;public class SocketMessage { public String message; public String date;} |
3.创建App.java类，用于启用spring boot和用于接收、发送消息的控制器。
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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 { // 发现消息 DateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); messagingTemplate.convertAndSend("/topic/callback", df.format(new Date())); return "callback"; }} |
“send”方法用于接收客户端发送过来的websocket请求。
@EnableScheduling注解为：启用spring boot的定时任务，这与“callback”方法相呼应，用于每隔1秒推送服务器端的时间。
4.在“resources/templates”目录下创建index.html文件：
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<!DOCTYPE html><html><head><title>玩转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 = { //连接状态 connected : false, //消息 message : '', rows : [] }; //连接 $scope.connect = function() { var socket = new SockJS('/my-websocket'); stompClient = Stomp.over(socket); stompClient.connect({}, function(frame) { // 注册发送消息 stompClient.subscribe('/topic/send', function(msg) { $scope.data.rows.push(JSON.parse(msg.body)); $scope.data.connected = true; $scope.$apply(); }); // 注册推送时间回调 stompClient.subscribe('/topic/callback', function(r) { $scope.data.time = '当前服务器时间：' + 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>玩转spring boot——websocket</h2> <h4> 出处：刘冬博客 <a href="http://www.cnblogs.com/goodhelper" rel="external nofollow" >http://www.cnblogs.com/goodhelper</a> </h4> <label>WebSocket连接状态:</label> <button type="button" ng-disabled="data.connected" ng-click="connect()">连接</button> <button type="button" ng-click="disconnect()" ng-disabled="!data.connected">断开</button> <br /> <br /> <div ng-show="data.connected"> <label>{{data.time}}</label> <br /> <br /> <input type="text" ng-model="data.message" placeholder="请输入内容..." /> <button ng-click="send()" type="button">发送</button> <br /> <br /> 消息列表： <br /> <table> <thead> <tr> <th>内容</th> <th>时间</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，还需要引用sockjs和stomp。
完整的项目结构，如下图所示：
三、运行效果
点击“连接”按钮，出现发送消息的输入框。并接收到服务器端的时间推送。
输入发送内容并点击“发送”按钮后，页面显示出刚才发送的消息。
点击“断开”按钮，则服务器端不会再推送消息。
总结
在开发一个基于web的即时通讯应用的过程中，我们还需考虑session的机制。
还需要一个集合来承载当前的在线用户，并做一个定时任务，其目的是用轮询的方式定时处理在线用户的状态，有哪些用户在线，又有哪些用户离线。
参考：
http://spring.io/guides/gs/scheduling-tasks/
http://spring.io/guides/gs/messaging-stomp-websocket/
代码地址：https://github.com/carter659/spring-boot-16
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持服务器之家。
原文链接：http://www.cnblogs.com/GoodHelper/p/7078381.html
