DWR例证1 -调用后台无参方法 _Web前端

DWR例子1 --调用后台无参方法

Step 1: Download

从网站下载 DWR: http://getahead.ltd.uk/dwr/download
导入jar
?dwr.jar
commons-logging-1.0.4.jar（dwr 3.0需要这个包）

Step 2: web.xml

修改 web.xml, 新增 DwrServlet
<servlet>
  <display-name>DWR Servlet</display-name>
  <servlet-name>dwr-invoker</servlet-name>
  <servlet-class>
    org.directwebremoting.servlet.DwrServlet
  </servlet-class>
  <init-param>
    <param-name>debug</param-name>
    <param-value>true</param-value>
  </init-param>
</servlet>
<servlet-mapping>
  <servlet-name>dwr-invoker</servlet-name>
  <url-pattern>/dwr/*</url-pattern>
</servlet-mapping>

?Step 3: dwr.xml

将远端 Java 物件注册到 dwr.xml
参考：dwr.jar/org.directwebremoting/dwr.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE dwr PUBLIC
    "-//GetAhead Limited//DTD Direct Web Remoting 3.0//EN"
    "http://getahead.org/dwr/dwr30.dtd">
<dwr>
	<allow>
		<create creator="new" javascript="helloWorld">
			<param name="class" value="com.wepull.dwr.HelloWorld"></param>
		</create>
	</allow>
</dwr>

?Step 3? 测试

测试 DWR
将代码放入应用服务器（比如Tomcat），启动。
然后在地址栏输入：
http://localhost:8080/工程名称/dwr

?Step?4 前台页面

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
	<head>
		<title>testDWR.html</title>

		<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
		<meta http-equiv="description" content="this is my page">
		<meta http-equiv="content-type" content="text/html; charset=UTF-8">

		<!--<link rel="stylesheet" type="text/css" href="./styles.css">-->
		<script type="text/javascript"
			src="/1102_DWR/dwr/interface/helloWorld.js"></script>
		<script type='text/javascript' src='/1102_DWR/dwr/engine.js'></script>

		<script type='text/javascript' src='/1102_DWR/dwr/util.js'></script>

		<script type="text/javascript">
		function sayHello(){
		
			//helloWorld 为helloWorld.js 中的helloWorld
			//callBack 是个回调函数
			helloWorld.sayHello(callBack);
		}
		//text为服务器传到前台的数据
		function callBack(text){
			alert(text);
		//	var obj = document.getElementById("sp1");
			//DWR 中可以$("sp1") 来获取对象 
			var obj = $("sp1"); //sp1是id名
			obj.innerHTML = text;
		}
		
	</script>
	</head>

	<body>
		<input type="button" value="调用后台sayHello()方法" onclick="sayHello()">
		<span id="sp1"></span>
	</body>
</html>

附：后台代码

package com.wepull.dwr;

public class HelloWorld {
	public String sayHello(){
		System.out.println("执行了 sayHello()方法");
		return "hello world";
	}
}