玩轉spring boot——websocket

時間 2019-11-24

原文原文鏈接

前言javascript

　　QQ這類即時通信工具多數是以桌面應用的方式存在。在沒有websocket出現以前，若是開發一個網頁版的即時通信應用，則須要定時刷新頁面或定時調用ajax請求，這無疑會加大服務器的負載和增長了客戶端的流量。而websocket的出現，則完美的解決了這些問題。css

spring boot對websocket進行了封裝，這對實現一個websocket網頁即時通信應用來講，變得很是簡單。html

1、準備工做java

pom.xml引入git

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

完整的pom.xml文件代碼以下：github

<?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>

pom.xml

2、代碼編寫web

1.建立名爲「WebSocketConfig.java」的類來配置websocket，並繼承抽象類「AbstractWebSocketMessageBrokerConfigurer」ajax

此類聲明「@EnableWebSocketMessageBroker」的註解spring

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
@EnableWebSocketMessageBroker
public 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();
    }

}

這裏配置了以「/app」開頭的websocket請求url。和名爲「my-websocket」的endpoint(端點)apache

2.編寫一個DTO類來承載消息：

package com.example;

public class SocketMessage {

    public String message;

    public String date;

}

3.建立App.java類，用於啓用spring boot和用於接收、發送消息的控制器。

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
@SpringBootApplication
public 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 {
        // 發現消息
        DateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        messagingTemplate.convertAndSend("/topic/callback", df.format(new Date()));
        return "callback";
    }
}

「send」方法用於接收客戶端發送過來的websocket請求。

@EnableScheduling註解爲：啓用spring boot的定時任務，這與「callback」方法相呼應，用於每隔1秒推送服務器端的時間。

4.在「resources/templates」目錄下建立index.html文件：

<!DOCTYPE html>
<html>
<head>
<title>玩轉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 = {
            //鏈接狀態
            connected : false,
            //消息
            message : '',
            rows : []
        };

        //鏈接
        $scope.connect = function() {
            var socket = new SockJS('/my-websocket');
            stompClient = Stomp.over(socket);
            stompClient.connect({}, function(frame) {
                // 註冊發送消息
                stompClient.subscribe('/topic/send', function(msg) {
                    $scope.data.rows.push(JSON.parse(msg.body));
                    $scope.data.connected = true;
                    $scope.$apply();
                });
                // 註冊推送時間回調
                stompClient.subscribe('/topic/callback', function(r) {
                    $scope.data.time = '當前服務器時間：' + 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鏈接狀態:</label>
    <button type="button" ng-disabled="data.connected" ng-click="connect()">鏈接</button>
    <button type="button" ng-click="disconnect()"
        ng-disabled="!data.connected">斷開</button>
    <br />
    <br />
    <div ng-show="data.connected">
        <label>{{data.time}}</label> <br /> <br /> <input type="text"
            ng-model="data.message" placeholder="請輸入內容..." />
        <button ng-click="send()" type="button">發送</button>
        <br /> <br /> 消息列表： <br />
        <table>
            <thead>
                <tr>
                    <th>內容</th>
                    <th>時間</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>