摘要: HTML5 WebSocket实现了服务器与浏览器的双向通讯，双向通讯使服务器消息推送开发更加简单，最常见的就是即时通讯和对信息实时性要求比较高的应用。以前的服务器消息推送大部分采用的都是“轮询”和“长连接”技术，这两中技术都会对服务器产生相当大的开销，而且实时性不是特别高。WebSocket技术对只会产生很小的开销，并且实时性特别高
文章源地址：https://my.oschina.net/u/136848/blog/781896
说明以tomcat容器为例，tomcat7以上版本开始支持websocket,JFinal集成的jetty服务器不支持websocket
一、包依赖，tomcat7或是javaee包都行，两者二选一，容器中已提供所以只作为提供者
<dependency> <groupId>org.apache.tomcat</groupId> <artifactId>tomcat-websocket-api</artifactId> <version>7.0.47</version> <scope>provided</scope> </dependency><dependency> <groupId>javax</groupId> <artifactId>javaee-api</artifactId> <version>7.0</version> <scope>provided</scope> </dependency>
二、JFinal的配置，需要一个Handler拦截websocket请求，WebSocketHandler实现如下
package com.nmtx.manager.handler;
import java.util.regex.Pattern;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.jfinal.handler.Handler;
import com.jfinal.kit.StrKit;
public class WebSocketHandler extends Handler{
private Pattern filterUrlRegxPattern;
public WebSocketHandler(String filterUrlRegx) {
if (StrKit.isBlank(filterUrlRegx))
throw new IllegalArgumentException("The para filterUrlRegx can not be blank.");
filterUrlRegxPattern = Pattern.compile(filterUrlRegx);
}
@Override
public void handle(String target, HttpServletRequest request, HttpServletResponse response, boolean[] isHandled) {
if (filterUrlRegxPattern.matcher(target).find())
return ;
else
next.handle(target, request, response, isHandled);
}
}JFinalConfig中配置
/**
* 接收处理跳转
*/
@Override
public void configHandler(Handlers me) {
me.add(new WebSocketHandler("^/websocket"));
}配置WebSocket处理类
package com.nmtx.manager.controller.websocket;import java.io.IOException;import javax.websocket.OnClose;import javax.websocket.OnMessage;import javax.websocket.OnOpen;import javax.websocket.Session;import javax.websocket.server.ServerEndpoint;import com.jfinal.kit.JsonKit;import com.jfinal.plugin.redis.Redis;import com.nmtx.common.ErrorCode;import com.nmtx.common.MessageResp;import com.nmtx.manager.common.base.LoggerManager;import com.nmtx.manager.model.message.Message;import com.nmtx.manager.model.permission.User;import com.nmtx.manager.utils.WebSocketSessionUtils;import com.nmtx.plugins.auth.AuthUser;import com.nmtx.utils.ModelUtils;@ServerEndpoint("/websocket")public class WebSocketController {
@OnOpen
public void onOpen(Session session) {
} @OnClose
public void onClose(Session session) {
} @OnMessage
public void onMessage(String requestJson, Session session) { session.getBasicRemote().sendText(requestJson);
}
}三，html5端请求
<!DOCTYPE html><html><head><meta charset="UTF-8"> <!-- for HTML5 -->
<title>Java后端WebSocket的Tomcat实现</title></head><body>
Welcome<br/><input id="text" type="text"/>
<button onclick="send()">发送消息</button>
<hr/>
<button onclick="closeWebSocket()">关闭WebSocket连接</button>
<hr/>
<div id="message"></div></body><script type="text/javascript">
var websocket = null; //判断当前浏览器是否支持WebSocket
if ('WebSocket' in window) {
websocket = new WebSocket("ws://localhost:8080/websocket");
} else {
alert('当前浏览器 Not support websocket')
} //连接发生错误的回调方法
websocket.onerror = function () {
setMessageInnerHTML("WebSocket连接发生错误");
}; //连接成功建立的回调方法
websocket.onopen = function () {
setMessageInnerHTML("WebSocket连接成功");
} //接收到消息的回调方法
websocket.onmessage = function (event) {
setMessageInnerHTML(event.data);
} //连接关闭的回调方法
websocket.onclose = function () {
setMessageInnerHTML("WebSocket连接关闭");
} //监听窗口关闭事件，当窗口关闭时，主动去关闭websocket连接，防止连接还没断开就关闭窗口，server端会抛异常。
window.onbeforeunload = function () {
closeWebSocket();
} //将消息显示在网页上
function setMessageInnerHTML(innerHTML) { document.getElementById('message').innerHTML += innerHTML + '<br/>';
} //关闭WebSocket连接
function closeWebSocket() {
websocket.close();
} //发送消息
function send() { var message = document.getElementById('text').value;
websocket.send(message);
}</script></html>
