先上代码，写的jsp页面，后台是tomcat服务器，所以页面里有一些java的代码，如果后台用其他语言可以无视：
<%@ page language=”java” contentType=”text/html; charset=UTF-8″
pageEncoding=”UTF-8″%>
<%@page import=”java.io.*”%>
<!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=UTF-8″>
<title>上传、下载文件</title>
<style type=”text/css”>
#filedrag {
display: none;
font-weight: bold;
text-align: center;
padding: 1em 0;
margin: 1em 0;
color: #555;
border: 2px dashed #555;
border-radius: 7px;
cursor: default;
}
#filedrag.hover {
color: #f00;
border-color: #f00;
border-style: solid;
box-shadow: inset 0 3px 4px #888;
}
</style>
</head>
<body>
<form id=”upload” action=”UploadServlet” enctype=”multipart/form-data”
method=”post” onsubmit=”return upLoad();”>
<p>
<label for=”fileselect”>file name:</label><input multiple=”true”
type=”file” id=”fileselect” name=”fileselect[]” />
<div id=”filedrag”>或者将文件拖拽到这里</div>
<div id=”submitbutton”>
<input type=”submit” value=”提交”>
</div>
</form>
<div id=”messages”>
</div>
<% //java代码，显示服务器上可以供下载的文件
File f = new File(“G://defggg/”);
File[] list = f.listFiles();
for (int i = 0; i < list.length; ++i) {
System.out.println(list[i].getName());
out.print(“<a href=’DownloadServlet?filename=”
+ list[i].getName() + “‘>” + list[i].getName()
+ “</a><br/>”);
}
%>
<script type=”text/javascript”>
var upfiles = new Array();
// getElementById
function $id(id) {
return document.getElementById(id);
}
// output information
function Output(msg) {
var m = $id(“messages”);
m.innerHTML = msg + m.innerHTML;
}
// file drag hover
function FileDragHover(e) {
e.stopPropagation();
e.preventDefault();
e.target.className = (e.type == “dragover” ? “hover” : “”);
}
// file selection
function FileSelectHandler(e) {
// cancel event and hover styling
FileDragHover(e);
