检查上传图片是否为真实图片.

  
    

   
     
   
     if
   
      CheckFileType(Server.MapPath(FileName))
   
     =
   
     false
   
      
   
     then
   
     
 
   
     set
   
      fileobject
   
     =
   
     server.createobject(
   
     "
   
     scripting.filesystemobject
   
     "
   
     )
 fileobject.deletefile server.mappath(FileName)
 
   
     end
   
      
   
     if
  
    

 

代码

   
     

    
      
    
      <
    
      %

    
      '
    
      ***************************************************************
    
      
'
    
      CheckFileType 函数用来检查文件是否为图片文件
    
      
'
    
      参数filename是本地文件的路径
    
      
'
    
      如果是文件jpeg,gif,bmp,png图片中的一种，函数返回true，否则返回false
    
      
'
    
      ***************************************************************
    
      

    
      

    
      const
    
       adTypeBinary
    
      =
    
      1
    
      


    
      dim
    
       jpg(
    
      1
    
      ):jpg(
    
      0
    
      )
    
      =
    
      CByte
    
      (
    
      &
    
      HFF):jpg(
    
      1
    
      )
    
      =
    
      CByte
    
      (
    
      &
    
      HD8)

    
      dim
    
       bmp(
    
      1
    
      ):bmp(
    
      0
    
      )
    
      =
    
      CByte
    
      (
    
      &
    
      H42):bmp(
    
      1
    
      )
    
      =
    
      CByte
    
      (
    
      &
    
      H4D)

    
      dim
    
       png(
    
      3
    
      ):png(
    
      0
    
      )
    
      =
    
      CByte
    
      (
    
      &
    
      H89):png(
    
      1
    
      )
    
      =
    
      CByte
    
      (
    
      &
    
      H50):png(
    
      2
    
      )
    
      =
    
      CByte
    
      (
    
      &
    
      H4E):png(
    
      3
    
      )
    
      =
    
      CByte
    
      (
    
      &
    
      H47)

    
      dim
    
       gif(
    
      5
    
      ):gif(
    
      0
    
      )
    
      =
    
      CByte
    
      (
    
      &
    
      H47):gif(
    
      1
    
      )
    
      =
    
      CByte
    
      (
    
      &
    
      H49):gif(
    
      2
    
      )
    
      =
    
      CByte
    
      (
    
      &
    
      H46):gif(
    
      3
    
      )
    
      =
    
      CByte
    
      (
    
      &
    
      H39):gif(
    
      4
    
      )
    
      =
    
      CByte
    
      (
    
      &
    
      H38):gif(
    
      5
    
      )
    
      =
    
      CByte
    
      (
    
      &
    
      H61)



    
      function
    
       CheckFileType(filename)

    
      on
    
       
    
      error
    
       
    
      resume
    
       
    
      next
    
      
CheckFileType
    
      =
    
      false
    
      

    
      dim
    
       fstream,fileExt,stamp,i
fileExt
    
      =
    
      mid
    
      (filename,
    
      InStrRev
    
      (filename,
    
      "
    
      .
    
      "
    
      )
    
      +
    
      1
    
      )

    
      set
    
       fstream
    
      =
    
      Server.createobject(
    
      "
    
      ADODB.Stream
    
      "
    
      )
fstream.Open
fstream.Type
    
      =
    
      adTypeBinary
fstream.LoadFromFile filename
fstream.position
    
      =
    
      0
    
      

    
      select
    
       
    
      case
    
       fileExt

    
      case
    
       
    
      "
    
      jpg
    
      "
    
      ,
    
      "
    
      jpeg
    
      "
    
      
stamp
    
      =
    
      fstream.read(
    
      2
    
      )

    
      for
    
       i
    
      =
    
      0
    
       
    
      to
    
       
    
      1
    
      

    
      if
    
       ascB(MidB(stamp,i
    
      +
    
      1
    
      ,
    
      1
    
      ))
    
      =
    
      jpg(i) 
    
      then
    
       CheckFileType
    
      =
    
      true
    
       
    
      else
    
       CheckFileType
    
      =
    
      false
    
      

    
      next
    
      

    
      case
    
       
    
      "
    
      gif
    
      "
    
      
stamp
    
      =
    
      fstream.read(
    
      6
    
      )

    
      for
    
       i
    
      =
    
      0
    
       
    
      to
    
       
    
      5
    
      

    
      if
    
       ascB(MidB(stamp,i
    
      +
    
      1
    
      ,
    
      1
    
      ))
    
      =
    
      gif(i) 
    
      then
    
       CheckFileType
    
      =
    
      true
    
       
    
      else
    
       CheckFileType
    
      =
    
      false
    
      

    
      next
    
      

    
      case
    
       
    
      "
    
      png
    
      "
    
      
stamp
    
      =
    
      fstream.read(
    
      4
    
      )

    
      for
    
       i
    
      =
    
      0
    
       
    
      to
    
       
    
      3
    
      

    
      if
    
       ascB(MidB(stamp,i
    
      +
    
      1
    
      ,
    
      1
    
      ))
    
      =
    
      png(i) 
    
      then
    
       CheckFileType
    
      =
    
      true
    
       
    
      else
    
       CheckFileType
    
      =
    
      false
    
      

    
      next
    
      

    
      case
    
       
    
      "
    
      bmp
    
      "
    
      
stamp
    
      =
    
      fstream.read(
    
      2
    
      )

    
      for
    
       i
    
      =
    
      0
    
       
    
      to
    
       
    
      1
    
      

    
      if
    
       ascB(MidB(stamp,i
    
      +
    
      1
    
      ,
    
      1
    
      ))
    
      =
    
      bmp(i) 
    
      then
    
       CheckFileType
    
      =
    
      true
    
       
    
      else
    
       CheckFileType
    
      =
    
      false
    
      

    
      next
    
      

    
      end
    
       
    
      select
    
      
fstream.Close

    
      set
    
       fseteam
    
      =
    
      nothing
    
      

    
      if
    
       err.number
    
      <>
    
      0
    
       
    
      then
    
       CheckFileType
    
      =
    
      false
    
      

    
      end function
    
      
%
    
      >