Multipart file uploading using winhttp.winhttprequest.5.1

[SeunghunBaek]

i'm trying to upload some image files to server using post method.

i got NullPointerException error from server that is implemented on spring framework.

the server didn't receive the capturedImageFile field.

please let me know what problem and solution are.
 
here is my piece of code

Local $boundary = "------" & _TimeToTicks(@HOUR, @MIN, @SEC)
Local $contentDisposition = "form-data; name=""capturedImageFile""; filename=""" & $sFileName & '"'
Local $contentType = "multipart/form-data"
Local $origin = "null"

$http = ObjCreate("winhttp.winhttprequest.5.1")
$http.Open("POST", $sUrl, False)
$http.SetRequestHeader("Content-Type", $contentType & "; boundary=" & $boundary)

Local $hFile = FileOpen($sFileName, 16)
Local $postData = $boundary & @LF
$postData &= 'Content-Disposition: form-data; name="capturedImageFile"; filename="' & $sFileName & '"' & @LF
$postData &= "Content-Type: " & "image/bmp;" & @LF
$postData &= @LF & FileRead($hFile) & @LF
$postData &=  $boundary & "--"
$http.Send($postData)
    
FileClose($hFile)