服务器端推送技术在web开发中比较常用，可能早期很多人的解决方案是采用ajax向服务器轮询消息，这种方式的轮询频率不好控制，所以大大增加了服务器的压力，后来有了下面的方案：当客户端向服务器发送请求时，服务器端会抓住这个请求不放，等有数据更新的时候才返回给客户端，当客户端接收到数据后再次发送请求，周而复始，这样就大大减少了请求次数，减轻了服务器的压力，当前主要有SSE(Server Send Event 服务器端事件发送)的服务器端推送和基于Servlet3.0+异步方法特性实现的服务器端推送。而本次我将利用webSokcet实现服务器端消息推送。话不多说上代码：
1、pom.xml，新建springboot项目，加入webSocket启动包spring-boot-starter-websocket；
2、WebSocketConfig
package com.example.demo.websocket;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 //注解开启STOMP协议来传输基于代理的消息，此时控制器支持使用@MessageMappingpublic class WebSocketConfig extends AbstractWebSocketMessageBrokerConfigurer { @Override public void configureMessageBroker(MessageBrokerRegistry config) { config.enableSimpleBroker("/topic","/user");//topic用来广播，user用来实现p2p } @Override public void registerStompEndpoints(StompEndpointRegistry registry) { registry.addEndpoint("/webServer").withSockJS(); registry.addEndpoint("/queueServer").withSockJS();//注册两个STOMP的endpoint，分别用于广播和点对点 } }
3、接收消息类：ReceiveMessage
package com.example.demo.websocket;public class ReceiveMessage { private String name; public String getName() { return name; } public void setName(String name) { this.name = name; }}
4、响应消息类：ResponseMessage
package com.example.demo.websocket;public class ResponseMessage { private String id; private String name; private String content; public String getId() { return id; } public void setId(String id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getContent() { return content; } public void setContent(String content) { this.content = content; } public ResponseMessage(String id, String name, String content) { super(); this.id = id; this.name = name; this.content = content; } }
5、控制器类：SubController
package com.example.demo.websocket;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.messaging.handler.annotation.MessageMapping;import org.springframework.messaging.simp.SimpMessagingTemplate;import org.springframework.stereotype.Controller;@Controllerpublic class SubController { @Autowired public SimpMessagingTemplate template; @MessageMapping("/subscribe") public void subscribe(ReceiveMessage rm) { for(int i =1;i<=20;i++) { //广播使用convertAndSend方法，第一个参数为目的地，和js中订阅的目的地要一致 template.convertAndSend("/topic/getResponse", rm.getName()); try { Thread.sleep(1000); } catch (InterruptedException e) { e.printStackTrace(); } } } @MessageMapping("/queue") public void queuw(ReceiveMessage rm) { System.out.println("进入方法"); for(int i =1;i<=20;i++) { /*广播使用convertAndSendToUser方法，第一个参数为用户id，此时js中的订阅地址为 "/user/" + 用户Id + "/message",其中"/user"是固定的*/ template.convertAndSendToUser("zhangsan","/message",rm.getName()); try { Thread.sleep(1000); } catch (InterruptedException e) { e.printStackTrace(); } } }}
6、在src/main/resource包下建一个static包，引入jquery-3.2.1.min.js、sock.js、stomp.js,创建topic.html和queue.html。
<html><head> <meta charset="UTF-8"> <title>Hello topic</title> <script src="sock.js"></script> <script src="stomp.js"></script> <script src="jquery-3.2.1.min.js"></script> <script type="text/javascript"> var stompClient = null; function setConnected(connected){ document.getElementById("connect").disabled = connected; document.getElementById("disconnect").disabled = !connected; $("#response").html(); } function connect() { var socket = new SockJS("/webServer"); stompClient = Stomp.over(socket); stompClient.connect({}, function(frame) { setConnected(true); console.log('Connected: ' + frame); stompClient.subscribe('/topic/getResponse', function(response){ var response1 = document.getElementById('response'); var p = document.createElement('p'); p.style.wordWrap = 'break-word'; p.appendChild(document.createTextNode(response.body)); response1.appendChild(p); }); }); } function disconnect() { if (stompClient != null) { stompClient.disconnect(); } setConnected(false); console.log("Disconnected"); } function sendName() { var name = document.getElementById('name').value; console.info(1111111111); stompClient.send("/subscribe", {}, JSON.stringify({ 'name': name })); } </script></head><body onload="disconnect()"><noscript><h2 style="color: #ff0000">Seems your browser doesn't support Javascript! Websocket relies on Javascript being enabled. Please enable Javascript and reload this page!</h2></noscript><div> <div> <button id="connect" onclick="connect();">Connect</button> <button id="disconnect" disabled="disabled" onclick="disconnect();">Disconnect</button> </div> <div id="conversationDiv"> <labal>名字</labal><input type="text" id="name" /> <button id="sendName" onclick="sendName();">Send</button> <p id="response"></p> </div></div></body></html>
<html><head> <meta charset="UTF-8"> <title>Hello queue</title> <script src="sock.js"></script> <script src="stomp.js"></script> <script src="jquery-3.2.1.min.js"></script> <script type="text/javascript"> var stompClient = null; function setConnected(connected){ document.getElementById("connect").disabled = connected; document.getElementById("disconnect").disabled = !connected; $("#response").html(); } function connect() { var socket = new SockJS("/queueServer"); stompClient = Stomp.over(socket); stompClient.connect({}, function(frame) { setConnected(true); console.log('Connected: ' + frame); stompClient.subscribe('/user/'+document.getElementById('user').value+'/message', function(response){ var response1 = document.getElementById('response'); var p = document.createElement('p'); p.style.wordWrap = 'break-word'; p.appendChild(document.createTextNode(response.body)); response1.appendChild(p); }); }); } function disconnect() { if (stompClient != null) { stompClient.disconnect(); } setConnected(false); console.log("Disconnected"); } function sendName() { var name = document.getElementById('name').value; console.info(1111111111); stompClient.send("/queue", {}, JSON.stringify({ 'name': name})); } </script></head><body onload="disconnect()"><noscript><h2 style="color: #ff0000">Seems your browser doesn't support Javascript! Websocket relies on Javascript being enabled. Please enable Javascript and reload this page!</h2></noscript><div> <div> <labal>用户</labal><input type="text" id="user" /> <button id="connect" onclick="connect();">Connect</button> <button id="disconnect" disabled="disabled" onclick="disconnect();">Disconnect</button> </div> <div id="conversationDiv"> <labal>名字</labal><input type="text" id="name" /> <button id="sendName" onclick="sendName();">Send</button> <p id="response"></p> </div></div></body></html>
启动项目后，先访问topic.html,如图所示
访问queue.html,首先以不同的用户名建立连接，如图所示
zhangsan窗口发送12345后：
lisi窗口发送67890后：
由此便实现了服务端两种推送消息的方式（广播 和点对点）。
联系客服
