图片上传的文件尺寸及文件类型问题！

[bouken]

各位高手：我最近写了一个图片上传的程序，图片的文件大小就可以控制，但图片的尺寸和文件类型就不知道应该如何进行限制了。我想在数据正式提交前有一个处理，这样应该可以减轻服务器的负担，利用javascript可以实现这个提交前的处理吗？请各位高手帮忙！我应该如何写呢？


以下是我的图片上传的程序：
<%
infoID=session("infoID")
response.buffer=true
formsize=request.totalbytes
formdata=request.binaryread(formsize)
bncrlf=chrB(13) & chrB(10)
divider=leftB(formdata,clng(instrb(formdata,bncrlf))-1)
datastart=instrb(formdata,bncrlf & bncrlf)+4
dataend=instrb(datastart+1,formdata,divider)-datastart
mydata=midb(formdata,datastart,dataend)

if formsize>1048576 then
%>
<script language="VBScript">
msgbox"对不起，您上传的文件太于1M,请重新选择另外一个文件！"
location.href="javascript:history.back()"
</script>
<%
end if
sql="update information set img ='' where infoID=" & infoID
conn.execute(sql)
set rec=server.createobject("ADODB.recordset")
sql="SELECT * FROM information where infoID=" & infoID

rec.Open sql,conn,1,3
rec("img")=""
rec("img").appendchunk mydata

rec.update

set rec=nothing
%>

[2599]

尺寸我忘记了，但是文件类型是用文件的后缀名来判断的
<%=right(path,4)%> path是你上传的文件名
然后对 right(path,4) 进行判断，如果符合你要上传的文件类型的话则给出相应的提示
if Right(path,4)=".gif" then
Response.Write "文件类型正确"
else
Response.Write "文件类型错误"
end if

[dreamfly8848]

利用FSO取得BMP，JPG，PNG，GIF文件信息(大小，宽、高等
<%
':::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
':::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
'::: BMP, GIF, JPG and PNG :::
':::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
':::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
'::: :::
'::: This function gets a specified number of bytes from any :::
'::: file, starting at the offset (base 1) :::
'::: :::
'::: Passed: :::
'::: flnm => Filespec of file to read :::
'::: offset => Offset at which to start reading :::
'::: bytes => How many bytes to read :::
'::: :::
':::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
function GetBytes(flnm, offset, bytes)
Dim objFSO
Dim objFTemp
Dim objTextStream
Dim lngSize
on error resume next
Set objFSO = CreateObject("Scripting.FileSystemObject")

' First, we get the filesize
Set objFTemp = objFSO.GetFile(flnm)
lngSize = objFTemp.Size
set objFTemp = nothing
fsoForReading = 1
Set objTextStream = objFSO.OpenTextFile(flnm, fsoForReading)
if offset > 0 then
strBuff = objTextStream.Read(offset - 1)
end if
if bytes = -1 then ' Get All!
GetBytes = objTextStream.Read(lngSize) 'ReadAll
else
GetBytes = objTextStream.Read(bytes)
end if
objTextStream.Close
set objTextStream = nothing
set objFSO = nothing
end function

':::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
'::: :::
'::: Functions to convert two bytes to a numeric value (long) :::
'::: (both little-endian and big-endian) :::
'::: :::
':::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
function lngConvert(strTemp)
lngConvert = clng(asc(left(strTemp, 1)) + ((asc(right(strTemp, 1)) * 256)))
end function
function lngConvert2(strTemp)
lngConvert2 = clng(asc(right(strTemp, 1)) + ((asc(left(strTemp, 1)) * 256)))
end function

':::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
'::: :::
'::: This function does most of the real work. It will attempt :::
'::: to read any file, regardless of the extension, and will :::
'::: identify if it is a graphical image. :::
'::: :::
'::: Passed: :::
'::: flnm => Filespec of file to read :::
'::: width => width of image :::
'::: height => height of image :::
'::: depth => color depth (in number of colors) :::
'::: strImageType=> type of image (e.g. GIF, BMP, etc.) :::
'::: :::
':::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
function gfxSpex(flnm, width, height, depth, strImageType)
dim strPNG
dim strGIF
dim strBMP
dim strType
strType = ""
strImageType = "(unknown)"
gfxSpex = False
strPNG = chr(137) & chr(80) & chr(78)
strGIF = "GIF"
strBMP = chr(66) & chr(77)
strType = GetBytes(flnm, 0, 3)
if strType = strGIF then ' is GIF
strImageType = "GIF"
Width = lngConvert(GetBytes(flnm, 7, 2))
Height = lngConvert(GetBytes(flnm, 9, 2))
Depth = 2 ^ ((asc(GetBytes(flnm, 11, 1)) and 7) + 1)
gfxSpex = True
elseif left(strType, 2) = strBMP then ' is BMP
strImageType = "BMP"
Width = lngConvert(GetBytes(flnm, 19, 2))
Height = lngConvert(GetBytes(flnm, 23, 2))
Depth = 2 ^ (asc(GetBytes(flnm, 29, 1)))
gfxSpex = True
elseif strType = strPNG then ' Is PNG
strImageType = "PNG"
Width = lngConvert2(GetBytes(flnm, 19, 2))
Height = lngConvert2(GetBytes(flnm, 23, 2))
Depth = getBytes(flnm, 25, 2)
select case asc(right(Depth,1))
case 0
Depth = 2 ^ (asc(left(Depth, 1)))
gfxSpex = True
case 2
Depth = 2 ^ (asc(left(Depth, 1)) * 3)
gfxSpex = True
case 3
Depth = 2 ^ (asc(left(Depth, 1))) '8
gfxSpex = True
case 4
Depth = 2 ^ (asc(left(Depth, 1)) * 2)
gfxSpex = True
case 6
Depth = 2 ^ (asc(left(Depth, 1)) * 4)
gfxSpex = True
case else
Depth = -1
end select

else
strBuff = GetBytes(flnm, 0, -1) ' Get all bytes from file
lngSize = len(strBuff)
flgFound = 0
strTarget = chr(255) & chr(216) & chr(255)
flgFound = instr(strBuff, strTarget)
if flgFound = 0 then
exit function
end if
strImageType = "JPG"
lngPos = flgFound + 2
ExitLoop = false
do while ExitLoop = False and lngPos < lngSize

do while asc(mid(strBuff, lngPos, 1)) = 255 and lngPos < lngSize
lngPos = lngPos + 1
loop
if asc(mid(strBuff, lngPos, 1)) < 192 or asc(mid(strBuff, lngPos, 1)) > 195 then
lngMarkerSize = lngConvert2(mid(strBuff, lngPos + 1, 2))
lngPos = lngPos + lngMarkerSize + 1
else
ExitLoop = True
end if
loop
'
if ExitLoop = False then
Width = -1
Height = -1
Depth = -1
else
Height = lngConvert2(mid(strBuff, lngPos + 4, 2))
Width = lngConvert2(mid(strBuff, lngPos + 6, 2))
Depth = 2 ^ (asc(mid(strBuff, lngPos + 8, 1)) * 8)
gfxSpex = True
end if

end if
end function

':::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
'::: Test Harness :::
':::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::

' To test, we'll just try to show all files with a .GIF extension in the root of C:
Set objFSO = CreateObject("Scripting.FileSystemObject")
Set objF = objFSO.GetFolder("c:\")
Set objFC = objF.Files
response.write "<table border=""0"" cellpadding=""5"">"
For Each f1 in objFC
if instr(ucase(f1.Name), ".GIF") then
response.write "<tr><td>" & f1.name & "</td><td>" & f1.DateCreated & "</td><td>" & f1.Size & "</td><td>"
if gfxSpex(f1.Path, w, h, c, strType) = true then
response.write w & " x " & h & " " & c & " colors"
else
response.write " "
end if
response.write "</td></tr>"
end if
Next
response.write "</table>"
set objFC = nothing
set objF = nothing
set objFSO = nothing

%>

[dreamfly8848]

这种方法简单
GIF： 在文件的第07H，08H，09H，0AH这四个字节就是它的尺寸（设第一个字节是01H）。 宽：07H（低字节），08H（高字节） 高：09H（低字节），0AH（高字节） JPG： 在文件的A4H，A5H，A6H，A7H这四个字节就是它的尺寸（设第一个字节是01H）。 宽：A4H（高字节），A5H（低字节） 宽：A6H（高字节），A7H（低字节） 注意：JPG和GIF的尺寸的高低字节相反！ 截取时注意用字节操作函数对它进行操作。 如：获得GIF图像的尺寸：（ASP） gifdata 中是图像文件的数据，则 imgW=asc(MidB(gifdata,&H7,1))+asc(MidB(gifdata,&H8,1)) * 256 '宽 imgW=asc(MidB(gifdata,&H9,1))+asc(MidB(gifdata,&HA,1)) * 256 '高 获得JPG图像的尺寸：（ASP） jpgdata 中是图像文件的数据，则 imgW=asc(MidB(jpgdata,&HA5,1))+asc(MidB(jpgdata,&HA4,1)) * 256 '宽 imgW=asc(MidB(jpgdata,&HA7,1))+asc(MidB(jpgdata,&HA6,1)) * 256 '高