One of the most important tasks in any programming language is the ability to read and write files. The steps involved in ASP are no different than many other languages:
- Specify the location of the file
- Determine if the file exists
- Get a handle to the file
- Read the contents
- Close the file and release any resources used
File I/O in ASP can be done using the FileSystemObject
component. When opening a text file you simply open it as a text stream, and it is this text stream that you use to access the contents of the file.
The FileSystemObject allows you to perform all file and folder handling operations. It can either return a file which can then be opened as a text stream, or it can return a text stream object directly.
In the following I present two different methods. The first method gets a file object and uses that to open the text stream, and the second method opens the text stream directly from the FileSystemObject
.
Method 1:
<% Option Explicit
Const Filename = "/readme.txt" ' file to read
Const ForReading = 1, ForWriting = 2, ForAppending = 3
Const TristateUseDefault = -2, TristateTrue = -1, TristateFalse = 0
' Create a filesystem object
Dim FSO
set FSO = server.createObject("Scripting.FileSystemObject")
' Map the logical path to the physical system path
Dim Filepath
Filepath = Server.MapPath(Filename)
if FSO.FileExists(Filepath) Then
' Get a handle to the file
Dim file
set file = FSO.GetFile(Filepath)
' Get some info about the file
Dim FileSize
FileSize = file.Size
Response.Write "<p><b>File: " & Filename & " (size " & FileSize &_
" bytes)</b></p><hr>"
Response.Write "<pre>"
' Open the file
Dim TextStream
Set TextStream = file.OpenAsTextStream(ForReading, TristateUseDefault)
' Read the file line by line
Do While Not TextStream.AtEndOfStream
Dim Line
Line = TextStream.readline
' Do something with "Line"
Line = Line & vbCRLF
Response.write Line
Loop
Response.Write "</pre><hr>"
Set TextStream = nothing
Else
Response.Write "<h3><i><font color=red> File " & Filename &_
" does not exist</font></i></h3>"
End If
Set FSO = nothing
%>
Method 2:
<% Option Explicit
Const Filename = "/readme.txt"
Const ForReading = 1, ForWriting = 2, ForAppending = 3
Const TristateUseDefault = -2, TristateTrue = -1, TristateFalse = 0
Dim FSO
set FSO = server.createObject("Scripting.FileSystemObject")
Dim Filepath
Filepath = Server.MapPath(Filename)
if FSO.FileExists(Filepath) Then
Set TextStream = FSO.OpenTextFile(Filepath, ForReading, False, TristateUseDefault)
Dim Contents
Contents = TextStream.ReadAll
Response.write "<pre>" & Contents & "</pre><hr>"
TextStream.Close
Set TextStream = nothing
Else
Response.Write "<h3><i><font color=red> File " & Filename &_
" does not exist</font></i></h3>"
End If
Set FSO = nothing
%>