此例子是基于jspsmartupload组件的，jspsmartupload是一个不错的上传下载组件，但对中文支持不足。若下载的文件名中有汉字，则浏览器在提示另存的文件名时，显示的是一堆乱码，让人看了很不舒服，为此，有人专门修改此组件，做了编码的转换工作，将文件名转换为UTF-8形式的编码形式。我用的是网上修改过的，已经可以支持中文，相信你也可以找到，如果需要，可以联系我，我会在第一时间发给你！jar down:

http://cid-75be94924ba7fb04.skydrive.live.com/self.aspx/Public/SmartUpload%5E_zh%5E_CN.jar

在网上找了很多相关资料，自己也添加了一些js代码，基本实现了动态添加删除多文件上传的功能，如果想要做得更完美，或者把文件上传下载信息存储到数据库等，那就自己去完善了，以下是所有的源代码：

(文件下载出于安全考虑是按流的方式来进行的，而不是直接给出文件下载路径地址，所以像迅雷等下载工具是不能下载的)

首先当然是上传下载的页面了，upfile.jsp

File Upload

function addFile(){

var upFile = '
';

document .getElementById ("files").insertAdjacentHTML("beforeEnd",upFile);

}

function deleteFile(){

var file = document .getElementById ("files").lastChild;

if(file == null)

return;

document .getElementById ("files").removeChild(file);

file = document .getElementById ("files").lastChild; //移除换行符
所以要移两次

document .getElementById ("files").removeChild(file); //如果在表格里面不加
就自动换行的，可以去掉，自己把握

}

基于jsp smart upload组件的文件上传下载

选择文件：

下载文件的名称：

上传文件UploadServlet类：

package com.xml.servlet;

import java.io.IOException;

import java.io.PrintWriter;

import javax.servlet.ServletConfig;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import com.jspsmart.upload.SmartUpload;

public class UploadServlet extends HttpServlet {

private ServletConfig config;

public UploadServlet() {

super();

}

public void destroy() {

super.destroy(); // Just puts "destroy" string in log

}

public void doGet(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

int count = 0; // 记录文件上传总个数

SmartUpload mySmartUpload = new SmartUpload();

mySmartUpload.initialize(config, request, response);

try {

// mySmartUpload.setAllowedFilesList("rar,htm,html,jar");//设置允许上传的文件

mySmartUpload.setDeniedFilesList("exe,jsp,asp");// 禁止上传的文件

mySmartUpload.setDenyPhysicalPath(true); // 拒绝物理路径

mySmartUpload.setMaxFileSize(5000000);// 设置允许上传文件最大为50000bytes

mySmartUpload.setTotalMaxFileSize(50000000);// 一次上传文件大小最多不超过5000000bytes

mySmartUpload.upload();

for (int i = 0; i < mySmartUpload.getFiles().getCount(); i++) {

com.jspsmart.upload.File myFile = mySmartUpload.getFiles().getFile(i);

String fileName = myFile.getFileName();

System.out.println("文件名：" + fileName);

}

count = mySmartUpload.save("/upload");

System.out.println(count + "文件已上传");

} catch (Exception e) {

e.printStackTrace();

}

}

public void doPost(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

doGet(request, response);

}

public void init(ServletConfig config) throws ServletException {

this.config = config;

}

}

下载文件DownloadServlet类：

package com.xml.servlet;

import java.io.IOException;

import java.io.PrintWriter;

import javax.servlet.ServletConfig;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import com.jspsmart.upload.SmartUpload;

import com.jspsmart.upload.SmartUploadException;

public class DownloadServlet extends HttpServlet {

private ServletConfig config;

public DownloadServlet() {

super();

}

public void destroy() {

super.destroy(); // Just puts "destroy" string in log

}

public void doGet(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

String temp_fileName = request.getParameter("downloadFileName");

if (temp_fileName == null || temp_fileName == "")

return;

byte[] temp_t = temp_fileName.getBytes("ISO8859_1");

String fileName = new String(temp_t, "GBK");

SmartUpload mySmartUpload = new SmartUpload();

mySmartUpload.initialize(config, request, response);

mySmartUpload.setContentDisposition(null);

/*

* 原型：public void setContentDisposition(String contentDisposition)

* 其中，contentDisposition为要添加的数据。

* 如果contentDisposition为null，则组件将自动添加"attachment;"，

* 以表明将下载的文件作为附件，结果是IE浏览器将会提示另存文件，而不是自动打开这个文件

* (IE浏览器一般根据下载的文件扩展名决定执行什么操作，扩展名为doc的将用word程序打开，

* 扩展名为pdf的将用acrobat程序打开，等等)。

*/

try {

mySmartUpload.downloadFile("/upload/" + fileName);

} catch (SmartUploadException e) {

e.printStackTrace();

}

}

public void doPost(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

doGet(request, response);

}

public void init(ServletConfig config) throws ServletException {

this.config = config;

}

}

web.xml配置文件：

xmlns="http://java.sun.com/xml/ns/j2ee"

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee

http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">

UploadServlet

com.xml.servlet.UploadServlet

DownloadServlet

com.xml.servlet.DownloadServlet

UploadServlet

/servlet/UploadServlet

DownloadServlet

/servlet/DownloadServlet

index.jsp