DWR基础入门使用-第一节

1.功能目的：

这个系列是想通过DWR最终实现服务器到客户端的推送，形象描述类似于在页面不刷新的前提下，页面会接收到服务器推送给当前用户的消息，以气泡形式展现。

2.为何使用DWR：

这里可以参考我博客中的其他文章，很大部门摘自于网络。十分感谢这些具备分享精神的同仁们。我这里就不详细阐述了。

3.DWR学习的一些相关资料：

官网地址：

http://directwebremoting.org/dwr/

其实针对于DWR的学习，官网已经给了非常详尽的资料了。在线demo，简单的部署教程以及API等等非常详细了。

学习demo下载地址：http://download.csdn.net/download/techbirds_bao/5505799

4.helloword的dwr基础入门

目录结构：

步骤

1.jar包导入

2.web.xml配置

<web-app id="dwr">

  <display-name>DWR (Direct Web Remoting)</display-name>
  <description>A Simple Demo DWR</description>

  <servlet>
    <servlet-name>dwr-invoker</servlet-name>
    <display-name>DWR Servlet</display-name>
    <description>Direct Web Remoter Servlet</description>
    <servlet-class>org.directwebremoting.servlet.DwrServlet</servlet-class>

    <!-- This should NEVER be present in live -->
    <init-param>
      <param-name>debug</param-name>
      <param-value>true</param-value>
    </init-param>

    <!-- Remove this unless you want to use active reverse ajax -->
    <init-param>
      <param-name>activeReverseAjaxEnabled</param-name>
      <param-value>true</param-value>
    </init-param>

    <!-- By default DWR creates application scope objects when they are first
    used. This creates them when the app-server is started -->
    <init-param>
      <param-name>initApplicationScopeCreatorsAtStartup</param-name>
      <param-value>true</param-value>
    </init-param>

    <!-- This enables full streaming mode. It's probably better to leave this
    out if you are running across the internet -->
    <init-param>
      <param-name>maxWaitAfterWrite</param-name>
      <param-value>-1</param-value>
    </init-param>

    <!--
    For more information on these parameters,see:
    - http://getahead.org/dwr/server/servlet
    - http://getahead.org/dwr/reverse-ajax/configuration
    -->

    <load-on-startup>1</load-on-startup>
  </servlet>

  <servlet-mapping>
    <servlet-name>dwr-invoker</servlet-name>
    <url-pattern>/dwr/*</url-pattern>
  </servlet-mapping>

</web-app>

3.dwr.xml配置

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

<dwr>

  <allow>
	<!-- base -->
	<create creator="new" javascript="Say" scope="application">
      <param name="class" value="org.getahead.dwrdemo.base.Say"/>
    </create>


  </allow>

</dwr>

4.dwr后台 调用java类编写

package org.getahead.dwrdemo.base;

public class Say {
	
	public String hello(){
		return "hello";
	}
	
	public String world(){
		return "world";
	}
}

5.页面 调用

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<Meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>dwr基础使用</title>
<script type='text/javascript' src='../dwr/engine.js'> </script>
<script type='text/javascript' src='../dwr/interface/Say.js'> </script>
<script type='text/javascript' src='../dwr/util.js'> </script>

</head>
<body onload="dwr.engine.setActiveReverseAjax(true);">
	<input type="button" value="say hello" onclick="sayHello();"/>
	<br/>
	<input type="button" value="say world" onclick="sayWorld();"/>
</body>
<script type="text/javascript">
	function sayHello(){
		Say.hello(function(data){
			alert(data);
		});
	}
	function sayWorld(){
		Say.world(function(data){
			alert(data);
		});
	}
</script>
</html>

原文链接：https://www.f2er.com/ajax/166280.html