struts2上传(图片带js预览)
    jsp页面:
<%@ page language="java" contentType="text/html; charset=GBK"
    pageEncoding="GBK"%>
<%@ taglib prefix="s" uri="/struts-tags" %>
<!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=GBK">
<title>Insert title here</title>
</head>
<script type="text/javascript">
	  // 显示图片的js
	function viewimg(){
		var imgup=document.getElementById("uploadimg");
		var imgpath=getPath(imgup);
		//判断是否是图片格式
		var imgname=imgup.value.substring(imgup.value.lastIndexOf("."),imgup.value.length)
		imgname=imgname.toLowerCase()
		if ((imgname!='.jpg')&&(imgname!='.gif')&&(imgname!='.jpeg')&&(imgname!='.png')&&(imgname!='.bmp')){
			alert("请选择图片文件,谢谢!");
			imgup.focus();
			//清空file里面的值
			imgup.select();   
			document.selection.clear();	
		}
		else{
		//显示图片
			document.getElementById("sig_preview").innerHTML="<img src='"+imgpath+"' border=0 width=100 height=60>"
		}
	}
	//该函数解决iE下路径问题。兼容ie6,7,firefox add by exceljava 2010-1-6
	function getPath(obj){
	   if(obj){
		   if (window.navigator.userAgent.indexOf("MSIE")>=1){
		     obj.select();
		     return document.selection.createRange().text;
		   }else if(window.navigator.userAgent.indexOf("Firefox")>=1){ 
		     if(obj.files){ 
		         	return obj.files.item(0).getAsDataURL();   
		     } 
		     return obj.value; 
		   }    
		   return obj.value;    
	   } 
	} 
</script>
<body>
<s:form action ="fileUpload" namespace="/fileUploadDemo" method ="POST" enctype ="multipart/form-data">
	<s:file id="uploadimg"  size="40" name="upload" onchange="viewimg()"></s:file>      
    <s:submit />	
</s:form>
<!-- 显示的div -->
<div id="sig_preview"></div>
</body>
</html>
action代码:
package UploadImages;
import java.io.File;
import javax.servlet.ServletContext;
import org.apache.commons.io.FileUtils;
import org.apache.struts2.util.ServletContextAware;
import com.opensymphony.xwork2.ActionSupport;
public class FileUploadAction extends ActionSupport implements
        ServletContextAware {
    private File upload;// 实际上传文件
    private String uploadContentType; // 文件的内容类型
    private String uploadFileName; // 上传文件名
    private String fileCaption;// 上传文件时的备注    
    private ServletContext context;
    public String execute() throws Exception {
        try {            
            String targetDirectory = context.getRealPath("/UploadImages");
            String targetFileName = uploadFileName;
            File target = new File(targetDirectory, targetFileName);