JSP图片上传教程：实现与限制

jsp图片上传代码
<%@ page contentType="text/html;charset=UTF-8" language="java" import="java.io.*,java.awt.Image,java.awt.image.*,com.sun.image.codec.jpeg.*,
java.sql.*,com.jspsmart.upload.*,java.util.*,cn.oof.database.*,cn.oof.house.*"%>
<%
SmartUpload mySmartUpload =new SmartUpload();
long file_size_max=5000000;
String fileName2="",ext="",testvar="";
String url="UploadFile/";      //应保证在根目录中有此目录的存在
//初始化
mySmartUpload.initialize(pageContext);
//只允许上载此类文件
try {
 mySmartUpload.setAllowedFilesList("rar,pdf,wrod,zip");
//上载文件 
 mySmartUpload.upload();
} catch (Exception e){
%>
  <SCRIPT language=javascript>
  alert("只允许上传.jpg、.bmp和.gif类型图片文件");
  window.location='upload.htm';
  </script>
<%
}
try{

    com.jspsmart.upload.File myFile = mySmartUpload.getFiles().getFile(0);
    if (myFile.isMissing()){%>
   <SCRIPT language=javascript>
   alert("请先选择要上传的文件");
   window.location='upload.htm';