首先在服务器端先创建一个程序可以生成XML文件，以返回客户端，（getfolder.asp）
%
'written by Linzhang Chen ,2003-4-20
' 转载请注明出处和保留此版权信息
response.write "?xml version=""1.0"" encoding=""GB2312""?>"chr(13)
response.write "mediafile>"chr(13)
folders=request("folder")
if folders="/" then
folders=""
end if
dim count
count=0
folders=replace(folders,"..","")
basefolder="../media/"'基准的文件夹路径
newfolder=basefolderfolders
Set fso =server.CreateObject("Scripting.FileSystemObject")
set f=fso.getfolder(server.mappath(newfolder))
set sf=f.subfolders
for each fd in sf'返回指定路径下面的文件夹列表
response.write "file>"chr(13)
response.write "ftype>folder/ftype>"chr(13)
response.write "fname>"fd.name"/fname>"chr(13)
response.write "/file>"chr(13)
count=count+1
next
set sf=nothing
set ff=f.Files
for each fi in ff
fname=fi.name
if instr("asf,wma,wmv",lcase(mid(fname,instrrev(fname,".")+1)))>0 then'设定允许返回的文件类型，防止源码泄露
response.write "file>"chr(13)
response.write "ftype>file/ftype>"chr(13)
response.write "fname>"fname"/fname>"chr(13)
response.write "/file>"chr(13)
count=count+1
end if
next
'如果该目录下没有文件，就发一个空元素
if count=0 then
response.write "file>"chr(13)
response.write "ftype>empty/ftype>"chr(13)
response.write "fname>0/fname>"chr(13)
response.write "/file>"chr(13)
end if
response.write "/mediafile>"
set ff=nothing
set f=nothing
set fso=nothing
%>
下面就是客户端的JS的功夫了(selectfile.asp)
!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
HTML>
HEAD>
TITLE> 选择视频文件 /TITLE>
style>
td{font-size:9pt}
select{width:210}
.s2{width:250}
/style>
SCRIPT LANGUAGE="javascript">
!--
/*written by Linzhang Chen ,2003-4-20
转载请注明出处和保留此版权信息 */

//预装载图片
var imgback = new Image();
imgback.src = "images/arrow.gif";
var imgbackgray = new Image();
imgbackgray.src = "images/grayarrow.gif";
var imgfolder = new Image();
imgfolder.src = "images/folder.gif";
var imggrayfolder = new Image();
imggrayfolder.src = "images/grayfolder.gif";
//历史记录数组栈
var arrhistory=new Array();
var hisi=0;
//用来确定要返回文件名
function check()
{
if (document.all.filename.value=="")
{
alert("请先选择文件");
return false;
}
else
{
window.returnValue =document.f1.folder.value+document.all.filename.value;
window.close();
}
}
//取得XML文件的内容
function getuserlist(url)
{ var oXMLDoc = new ActiveXObject('MSXML');
oXMLDoc.url = url;
var ooRoot=oXMLDoc.root;
return ooRoot;
}
//当选中一个文件时，把这个值返回给文本框
function addfile(txt)
{
document.all.filename.value=txt;
}

var first=1;//定义一个全局变量

function userlist(folders,ti)//列出所选框
{document.f1.folder.value=folders;
filebox.document.body.innerHTML="正在加载文件，请稍侯...";
var strshow="";
var timeoutid=null;
var newfolder="";
var arrfolder=new Array();
var arrff=new Array();
var blankstr="";
var oItem;
//确定历史状态
hisi+=ti;
arrhistory[hisi]=folders;
if (hisi==0)
{
arrow.innerHTML="img src=\&;images/grayarrow.gif\&;>";
}
else
{
arrow.innerHTML="img src=\&;images/arrow.gif\&; border=0 style=\&;cursor:hand\&; onclick=\&;userlist('"+arrhistory[hisi-1]+"',-1)\&; onmouseover=\&;this.src='images/arrow_over.gif'\&; onmouseout=\&;this.src='images/arrow.gif'\&;>";
}
//确定当前的文件夹
if (document.f1.folder.value=="")
{
folderid.innerHTML="img src=\&;images/grayfolder.gif\&;>"
}
else
{newsfolder=checkfolder(document.f1.folder.value)
folderid.innerHTML="img src=\&;images/folder.gif\&; border=0 style=\&;cursor:hand\&; onclick=\&;userlist('"+newsfolder+"',1)\&; onmouseover=\&;this.src='images/folder_over.gif'\&; onmouseout=\&;this.src='images/folder.gif'\&;>"
}
//给下拉框赋值
document.all.select.options.length=0;
newfolder=folders;
folderstr=""
var _obj=document.all.select;
var _o=document.createElement("Option");
_o.text="选择文件夹";
_o.value="";
_obj.add(_o);
if (newfolder!="")
{arrfolder=newfolder.split("/")
for(var i=0;iarrfolder.length-1;i++)
{blankstr+=" ";
folderstr+=arrfolder[i]+"/";
_o=document.createElement("Option");
_o.text=blankstr+arrfolder[i];
_o.value=folderstr;
_obj.add(_o);

}
}
document.all.select.options[document.all.select.options.length-1].selected=true;
url="getfolder.asp.gl?folder="+folders;
oRoot=getuserlist(url)
strshow="table class=file cellspacing=0 cellpadding=0>";
len=oRoot.children.length;
if (len==1)
{oItem = oRoot.children.item(0);
if(oItem.children.item(0).text=="empty")
strshow="没有文件和文件夹了";
else
{
if(oItem.children.item(0).text=="folder")
{
strshow+="tr>td>A href=\&;javascript:parent.userlist('"+folders+oItem.children.item(1).text+"/"+"',1)\&;>img src=\&;images/mediafolder.gif\&; border=0 >"+oItem.children.item(1).text+"/A>/td>/tr>";
}
else
{
strshow+="tr>td>a href=\&;javascript:parent.addfile('"+oItem.children.item(1).text+"')\&; >img src=\&;images/mediafile.gif\&; border=0>"+oItem.children.item(1).text+"/A>/td>/tr>";

}
}
strshow+="/table>"
}
else{
//数据入栈
for(i=0;ilen;i++)
{ oItem = oRoot.children.item(i);
if(oItem.children.item(0).text=="folder")
{
arrff[i]="A href=\&;javascript:parent.userlist('"+folders+oItem.children.item(1).text+"/"+"',1)\&;>img src=\&;images/mediafolder.gif\&; border=0>"+oItem.children.item(1).text+"/A>";
}
else
{
arrff[i]="A href=\&;javascript:parent.addfile('"+oItem.children.item(1).text+"')\&;>img src=\&;images/mediafile.gif\&; border=0 height=12>"+oItem.children.item(1).text+"/A>";

}
}
//取得要输出的列数
if (len=6)
{x=1;
y=6;}
else
{x=len/6;
y=6;}
for(var i=0;iy;i++)
{strshow+="tr>"
for(var j=0;jx;j++)
{ponits=j*y+i;
if (ponits>=len)
{
strshow+="td>nbsp;/td>";
}
else
{
strshow+="td>"+arrff[ponits]+"/td>";
}
}
strshow+="/tr>"
}

strshow+="/table>"
}
filebox.document.body.innerHTML=strshow;
}
//-->
/SCRIPT>
script LANGUAGE="vbscript">
function checkfolder(folderstr)
if (folderstr="" or instr(folderstr,"/")=instrrev(folderstr,"/")) then
checkfolder=""
else
nfolder=left(folderstr,len(folderstr)-1)
checkfolder=left(nfolder,instrrev(nfolder,"/"))
end if
end function
/script>
/HEAD>

BODY style="margin:0" bgColor=menu onload="javascript:userlist('',0)">
table width="443" border="0" cellspacing="0">
tr>
td height="36">table width="409" border="0">
tr>
td width="73" align="right">查找范围(u>I/u>):/td>
td width="214">select name="select" id="select" size="1" onchange="javascript:userlist(this.value,1);">
/select>/td>
td width="22" valign="baseline" id="arrow" align=right>/td>
td width="20" valign="middle" id="folderid">/td>
td width="20" align="left">img src="images/md.gif" width="16" height="15">/td>
td width="28" align="left">img src="images/viewtype.gif" width="23" height="14">/td>
/tr>
/table>/td>
/tr>
tr>
td height="120">table width="100%" height="100%" border="0">
tr>
td width="9">nbsp;/td>
td >
iframe src="blank.htm" width=415 height=120 id="filebox">/iframe>/td>
td width="13">nbsp;/td>
/tr>
/table>/td>
/tr>
tr>
td height="60">table width="100%" border="0">
FORM METHOD=POST ACTION="" name="f1">
input type="hidden" name="folder" value="">
tr>
td width="85" align="right">文件名(u>N/u>):nbsp;nbsp;/td>
td width="254">input type="text" id="filename" size="34">/td>
td>button onclick="javascript:return check()"> 打开(u>O/U>)/button>/td>
/tr>
/FORM>
tr>
td align="right">文件类型(u>T/u>):/td>
td>select name="select2" class=s2>
option>流媒体文件(*.asf,*.wmv,*.wma)/option>
/select>/td>
td>input type="button" name="Submit" value=" 取消 " onclick="window.close();">/td>
/tr>
/table>/td>
/tr>
/table>
/BODY>
/HTML>

里面还有一个小文件blank.htm用来定义文件和文件夹显示的样式
!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
HTML>
HEAD>
TITLE> New Document /TITLE>
style>
td{font-size:9pt}
body{font-size:9pt}
.file A{COLOR: #000000; TEXT-DECORATION: none;font-size:9pt}
.file A:visited{COLOR: #000000; TEXT-DECORATION: none;font-size:9pt}
.file A:hover {COLOR: #000000; TEXT-DECORATION: none;font-size:9pt}
/style>
/HEAD>

BODY style="margin: 0pt">

/BODY>
/HTML>
调用的时候用以下函数，就可以实现以假乱真的服务器端选择文件的效果
function selectfile()
{
var arr = showModalDialog("selectfile.asp?temp="+Math.random(), "", "dialogWidth:453px; dialogHeight:252px; status:0;help:1");
if (arr != null)
{
return arr
}
}