基于dwr框架的java推送

初学DWR框架

原理：dwr框架把java的类转成js，当前端的数据发送时，用js传到后端类.js,通过反射到该类的方法，然后调用返回函数，进行页面展示项目：我对慕课上的小项目（bs上进行推送消息的系统）进行改进，使他可以进行文字，英文单词的推送（项目连接，里面包括engines.js以及util.js,还有dwr.jar等等）配置：web.xml

<servlet>
<servlet-name>dwr</servlet-name>
<servlet-class>org.directwebremoting.servlet.DwrServlet</servlet-class>
<init-param>
<param-name>debug</param-name>
<param-value>true</param-value>
</init-param>

//下面这些初始化是必要的，不然会报错！！！
<init-param>
<param-name>crossDomainSessionSecurity</param-name>
<param-value> false</param-value>
</init-param>
<init-param>
<param-name>allowScriptTagRemoting</param-name>
<param-value> true</param-value>
</init-param>
<init-param>
<param-name>activeReverseAjaxEnabled</param-name>
<param-value>true</param-value>
</init-param>
</servlet>

dwr.xml我的理解：它的配置是使得java类转换成js

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE dwr PUBLIC "-//GetAhead Limited//DTD Direct Web Remoting 2.0//EN" "http://www.getahead.ltd.uk/dwr/dwr20.dtd">

<dwr>

<allow>

<create creator="new" javascript="自己定义的类">

<param name="class" >自己定义的类完整路径</param>

</create>

</allow>

</dwr>

还要导入响应的engine.js，util.js，dwr.jar等等js页面

<script type='text/javascript' src='../js/dwr/util.js'></script>

<script type='text/javascript' src='../js/dwr/engine.js'></script>

<script type='text/javascript' src='../js/dwr/interface/DwrPush.js'></script>
//这个是因为页面里面使用了$
<script type='text/javascript' src='../js/libs/jquery.js'></script>

$(document).ready(
function(){

//方法来启动该页面的ReverseAjax功能。这时候默认采用的将是comet的方式来完成页面内容的推送
dwr.engine.setActiveReverseAjax(true);
$("#sign").click(function(){

//注意java的类已经被转成js了，所有直接调用该类的send方法
DwrPush.send($("#msg").val());
})
}

function callback(xx){

}

DwrPush 类

public class DwrPush {public void send(String msg){WebContext webContext=WebContextFactory.get();Collection sessions=webContext.getAllScriptSessions();//获取所有的session，已用来全部推送ScriptBuffer sb=new ScriptBuffer();sb.appendScript("callback(");//调用回调函数sb.appendScript("\""+msg+"\"");sb.appendScript(")");Util util=new Util(sessions);util.addScript(sb);}}