WebSocket和Servlet3.0服务器消息推送技术

本文主要是介绍WebSocket和Servlet3.0服务器消息推送技术，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

最近研究了两种服务器消息推送技术，一种是WebSocket技术，一种是基于Servlet3.0实现的服务器异步消息推送技术，具体实现如下：

1. WebSocket（聊天室）

WebSocket客户端连接类（javaee-api-7.0.jar）

import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;import javax.websocket.OnClose;
import javax.websocket.OnError;
import javax.websocket.OnMessage;
import javax.websocket.OnOpen;
import javax.websocket.Session;
import javax.websocket.server.ServerEndpoint;/*** @ServerEndpoint 功能主要是将CharRoomServer 定义为websocket服务器端*/
@ServerEndpoint("/ws/charRoomServer")
public class CharRoomServer {// 会话，主要用于向客户端发送数据private Session session;public Session getSession() {return session;}/*** websocket连接* @param session*/@OnOpenpublic void onOpen(Session session){this.session = session;SessionManager.add(this);     }/*** websocket断开*/@OnClosepublic void onClose(){SessionManage.remove(this);}/*** websocket消息* @param message* @param session*/@OnMessagepublic void onMessage(String message, Session session) {Date date = new Date();SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");String messageFormat = "{\"date\":\"%s\",\"name\":\"%s\",\"content\":\"%s\"}";String msg = String.format(messageFormat, sdf.format(date),"客户端" + session.getId(), message);// 广播SessionManage.broadCast(msg);}/*** websocket错误* @param session* @param error*/@OnErrorpublic void onError(Session session, Throwable error){error.printStackTrace();}/*** 广播消息方法* @param message* @throws IOException*/public void sendMessage(String message) throws IOException{this.session.getBasicRemote().sendText(message);}}

SessionManage类

import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Date;public class SessionManage {private static Collection<CharRoomServer> charRoomServers = Collections.synchronizedCollection(new ArrayList<CharRoomServer>());/*** 广播* @param msg*/public static void broadCast(String msg){for (CharRoomServer charRoomServer : charRoomServers) {try {charRoomServer.sendMessage(msg);} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}/*** 新增客户端服务器* @param charRoomServer*/public static void add(CharRoomServer charRoomServer){// 使用时间构造登录信息Date date = new Date();SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");String messageFormat = "{\"date\":\"%s\",\"name\":\"系统\",\"content\":\"%s\"}";String content = "欢迎客户端" + charRoomServer.getSession().getId();String message = String.format(messageFormat, sdf.format(date), content);// 广播broadCast(message);// 加入服务组charRoomServers.add(charRoomServer);}/*** 客户端服务器退出* @param charRoomServer*/public static void remove(CharRoomServer charRoomServer){// 客户端服务器退出charRoomServers.remove(charRoomServer);// 使用时间构造退出信息Date date = new Date();SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");String messageFormat = "{\"date\":\"%s\",\"name\":\"系统\",\"content\":\"%s\"}";String name = "客户端" + charRoomServer.getSession().getId();String message = String.format(messageFormat, sdf.format(date), name + "已退出");// 广播broadCast(message);}}

2. Servlet3.0（SpringBoot：DeferredResult）

Application 入口类

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.scheduling.annotation.EnableAsync;
import org.springframework.scheduling.annotation.EnableScheduling;@SpringBootApplication
@EnableAsync
@EnableScheduling
public class Application {public static void main(String[] args) {SpringApplication.run(Application.class, args);}}

AsyncController异步控制器

import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.context.request.async.DeferredResult;/*** 异步控制器*/
@RequestMapping("/async")
@RestController
public class AsyncController {private DeferredResult<String> deferredResult;@RequestMapping("/getDeferredResult")public DeferredResult<String> getDeferredResult() {deferredResult = new DeferredResult<String>();return deferredResult;}/*** 每2秒执行一次*/@Scheduled(fixedDelay = 2000)public void refreshDeferredResult() {if (deferredResult != null) {String result = "getDeferredResult:" + System.currentTimeMillis();deferredResult.setResult(result);}}@RequestMapping("/getResult")public String getResult() {return "getResult";}
}

前端页面关键js代码

function getDeferredResult() {$.ajax({url:"/async/getDeferredResult",type:"post",success:function(data){$("table").html(data);getDeferredResult();}});
}
getDeferredResult();

pom文件配置

<?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.async</groupId><artifactId>async</artifactId><version>0.0.1-SNAPSHOT</version><!-- 编码和版本 --><properties><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding><project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding><java.version>1.8</java.version><maven.compiler.plugin.version>3.7.0</maven.compiler.plugin.version></properties><parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>1.5.3.RELEASE</version><relativePath/> <!-- lookup parent from repository --></parent><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency></dependencies>
</project>

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