dwr异步上传图片

这里需要用到commons-fileupload-1.2.2和commons-io-2.3

This is the web.xml 

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
	http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
	<servlet>
		<servlet-name>dwr-invoker</servlet-name>
		<servlet-class>org.directwebremoting.servlet.DwrServlet</servlet-class>
		<!-- 配置debug参数为true后，就可以访问DWR的控制台了，访问地址为

http://ip:port/webApp/dwr/ -->
		<!-- 开发阶段可以开启控制台，但在产品交付时，务必关掉控制台 -->
		<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>
</web-app>

This is DWR Config File----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="JSUserManager">
			<param name="class" value="com.jadyer.dwr.UserManager" />
		</create>
	</allow>
</dwr>

下面是用于提交上传操作的前台页面upload.jsp

<%@ page language="java" pageEncoding="UTF-8"%>

<script type="text/javascript" src="<%=request.getContextPath

()%>/dwr/interface/JSUserManager.js"></script>
<script type="text/javascript" src="<%=request.getContextPath()%>/dwr/engine.js"></script>
<script type="text/javascript" src="<%=request.getContextPath()%>/dwr/util.js"></script>

<script type="text/javascript">
	function upload() {
		var file = dwr.util.getValue("myfile");
		alert(file.value);//不同浏览器在此处得到的值,不一定相同....IE9得到的是含全

路径的文件名,firefox12得到的是文件名
		alert(file);
		JSUserManager.upload(file, file.value, function(data){
			alert(data);
		});
	}
</script>

<input type="file" id="myfile"/>
<input type="button" value="上传文件" onclick="upload()"/>

最后是需要由DWR发布的UserManager.java

import java.io.File;
import java.io.IOException;
import java.io.InputStream;

import javax.servlet.http.HttpServletRequest;

import org.apache.commons.io.FileUtils;
import org.apache.commons.io.FilenameUtils;
import org.directwebremoting.WebContextFactory;

public class UserManager {
	/**
	 * 上传文件
	 * @param is       DWR会自动把dwr.util.getValue("myfile")转换为这里所需的

InputStream
	 * @param filename 不同浏览器传进来的值未必相同，IE9传是含全路径的文件名,firefox12

传的是文件名
	 * @return 文件的真实名字
	 */
	public String upload(InputStream is, String filename) throws IOException{
		String realname = FilenameUtils.getName(filename);                          

  //获取文件的真实名字
		HttpServletRequest request = WebContextFactory.get().getHttpServletRequest

(); //获取Servlet API
		String realpath = request.getSession().getServletContext().getRealPath

("/WEB-INF/upload");
		FileUtils.copyInputStreamToFile(is, new File(realpath, realname));
		return realname;
	}
}

补充：记得建立//WEB-INF//upload//

目录，其用于接收所上传的文件