ASP.NET 文件上传范例
ASP.NET File Upload Example
Jose M. Esteban
March 28, 2001
Level: Beginner/Intermediate
示例代码路径：
http://sunrise.szu.edu.cn:8096/Article%20Source%20Code/art030_UploadFile.zip
ASP.NET provides an easy mechanism to upload files from a Web Browser to
a Web Server. The class HtmlInputFile allows to handle programmatically
the information submitted by the INPUT control of the type file, e.g.,
<input type"file">. Remember that the Input control of type file is
only available in Web Browsers that support HMTL 3.2 and later versions.
This HTML version is supported by IE 3.02 and Netscape 3.0 and their
later versions.
There are two objects that you will use to upload files. One is the
INPUT control in the Web Browser and the other is the HtmlInputFile
object in the server. The INPUT control will be embedded inside a form
that will post the information encoded in a format suitable for a file
transfer over the Internet. The INPUT control will also load the
selected file into the Web Browser's memory, and will allow access
to the HtmlInputFile object in the code that runs in the server
through the INPUT control's ID. I.e., you use the ID of the INPUT
control as the reference to the HtmlInputFile object in the code that
runs at the server.
To upload a file, the form must post the data with the code format
multiform/form-data instead of the default
application/x-www-form-urlencoded that sends the form elements in a
name/value pair base. This restriction arises from the types of
formats that an object of the class HtmlInputFile is capable of
processing and the characters that can traverse the Internet without
confusing the network devices and software. The following example
shows how to set the encoding format of a form:
<input type=file id=loFile enctype="multipart/form-data"
Once the data is submitted to the server, the object of the class
HtmlInputFile exposes the property PostedFile, with an object of the
type HttpPostedFile, that contains the raw file stream and the
attributes of the file, such as, file length, file type, file name.
But most important, the PostedFile object has the SaveAs method that
allows to save the uploaded file to a local directory in the web server.
You can also limit the type of the files you will allow users to upload
by setting the Access property of the HtmlInputFile object, and you can
also discard files base on the length by using the PostedFile.
ContentLength property. The following example shows how to restrict
the upload of video files. The ID loFile is the ID of the INPUT control.
loFile.Acess = "video/*"
The example that follows shows how to enable a web form for file uploads
and how to answer back to the user with a message and information about
the file that was just uploaded. The web form is contained in a panel
(FileUploadForm) that is initially visible and the answer is presented
in a panel (AnswerMsg) that is initially disable. Once the file is
uploaded, the web form panel is set to invisible and the message panel
is set to visible.
The event that handles the submitted form runs at the server as
indicated by the Submit INPUT tag:
<input type="submit" value="Upload" OnServerClick="UploadFile_Clicked"
runat="server" ID=Submit1>
The Directory and File classes allow to create a folder to contain the
uploaded files and to get the name of the uploaded file filtering the
path. In order to use this classes we need to include the System.IO name
space, we can do so by including the import directive. This entry
allows the upload the name space into the web form application, for more
information on this topic read the article How to Manipulate Files in
ASP.NET:
<%@ Import Namespace="System.IO" %>
For those of you that were familiar with uploading files in ASP, the
HtmlInputFile class free us from the need of third party components to
process the multipart data stream.
Demo this code
<%@ Import Namespace="System.IO" %>
<html>
<SCRIPT LANGUAGE="VB" RUNAT="SERVER" ID=SCRIPT1>
Sub UploadFile_Clicked(Sender as Object, e as EventArgs)
Dim lstrFileName as string
Dim lstrFileNamePath as string
Dim lstrFileFolder as string
lstrFileFolder = "C:\TempUploadedFiles\"
'Gets the file name
lstrFileName = loFile.PostedFile.FileName
lstrFileName = File.GetFileNameFromPath(lstrFileName)
'Creates the folder if it does not exists
If (not Directory.DirectoryExists(lstrFileFolder)) Then
Directory.CreateDirectories(lstrFileFolder)
End If
'Save Uploaded file to server
lstrFileNamePath = lstrFileFolder & lstrFileName
loFile.PostedFile.SaveAs(lstrFileNamePath)
'Sets the answer
FileName.Text = lstrFileName
FileType.Text = loFile.PostedFile.ContentType
FileLength.Text = cStr(loFile.PostedFile.ContentLength)
FileUploadForm.visible = false
AnswerMsg.visible = true
End sub
</SCRIPT>
<BODY>
<ASP:panel id="FileUploadForm" visible="true" runat="server">
<form action="UploadFile.aspx" method="post"
enctype="multipart/form-data"
runat="server" ID=Form1>
<h1>ASP.NET File Upload Example</h1>
Select the File to Upload to the Server:<br>
<input id="loFile" type="file" runat="server"><br>
<input type="submit" value="Upload"
OnServerClick="UploadFile_Clicked"
runat="server"
ID=Submit1>
</form>
</ASP:panel>
<ASP:panel id="AnswerMsg" visible="false" runat="server">
Thanks your file <ASP:label id="FileName" runat="server" />
has been uploaded<BR>
We received <ASP:label id="FileLength" runat="server" />
bytes of the type <ASP:label id="FileType" runat="server" />
</ASP:panel>
</BODY>
</HTML>
Jose M. Esteban
March 28, 2001
Level: Beginner/Intermediate
示例代码路径：
http://sunrise.szu.edu.cn:8096/Article%20Source%20Code/art030_UploadFile.zip
ASP.NET provides an easy mechanism to upload files from a Web Browser to
a Web Server. The class HtmlInputFile allows to handle programmatically
the information submitted by the INPUT control of the type file, e.g.,
<input type"file">. Remember that the Input control of type file is
only available in Web Browsers that support HMTL 3.2 and later versions.
This HTML version is supported by IE 3.02 and Netscape 3.0 and their
later versions.
There are two objects that you will use to upload files. One is the
INPUT control in the Web Browser and the other is the HtmlInputFile
object in the server. The INPUT control will be embedded inside a form
that will post the information encoded in a format suitable for a file
transfer over the Internet. The INPUT control will also load the
selected file into the Web Browser's memory, and will allow access
to the HtmlInputFile object in the code that runs in the server
through the INPUT control's ID. I.e., you use the ID of the INPUT
control as the reference to the HtmlInputFile object in the code that
runs at the server.
To upload a file, the form must post the data with the code format
multiform/form-data instead of the default
application/x-www-form-urlencoded that sends the form elements in a
name/value pair base. This restriction arises from the types of
formats that an object of the class HtmlInputFile is capable of
processing and the characters that can traverse the Internet without
confusing the network devices and software. The following example
shows how to set the encoding format of a form:
<input type=file id=loFile enctype="multipart/form-data"
Once the data is submitted to the server, the object of the class
HtmlInputFile exposes the property PostedFile, with an object of the
type HttpPostedFile, that contains the raw file stream and the
attributes of the file, such as, file length, file type, file name.
But most important, the PostedFile object has the SaveAs method that
allows to save the uploaded file to a local directory in the web server.
You can also limit the type of the files you will allow users to upload
by setting the Access property of the HtmlInputFile object, and you can
also discard files base on the length by using the PostedFile.
ContentLength property. The following example shows how to restrict
the upload of video files. The ID loFile is the ID of the INPUT control.
loFile.Acess = "video/*"
The example that follows shows how to enable a web form for file uploads
and how to answer back to the user with a message and information about
the file that was just uploaded. The web form is contained in a panel
(FileUploadForm) that is initially visible and the answer is presented
in a panel (AnswerMsg) that is initially disable. Once the file is
uploaded, the web form panel is set to invisible and the message panel
is set to visible.
The event that handles the submitted form runs at the server as
indicated by the Submit INPUT tag:
<input type="submit" value="Upload" OnServerClick="UploadFile_Clicked"
runat="server" ID=Submit1>
The Directory and File classes allow to create a folder to contain the
uploaded files and to get the name of the uploaded file filtering the
path. In order to use this classes we need to include the System.IO name
space, we can do so by including the import directive. This entry
allows the upload the name space into the web form application, for more
information on this topic read the article How to Manipulate Files in
ASP.NET:
<%@ Import Namespace="System.IO" %>
For those of you that were familiar with uploading files in ASP, the
HtmlInputFile class free us from the need of third party components to
process the multipart data stream.
Demo this code
<%@ Import Namespace="System.IO" %>
<html>
<SCRIPT LANGUAGE="VB" RUNAT="SERVER" ID=SCRIPT1>
Sub UploadFile_Clicked(Sender as Object, e as EventArgs)
Dim lstrFileName as string
Dim lstrFileNamePath as string
Dim lstrFileFolder as string
lstrFileFolder = "C:\TempUploadedFiles\"
'Gets the file name
lstrFileName = loFile.PostedFile.FileName
lstrFileName = File.GetFileNameFromPath(lstrFileName)
'Creates the folder if it does not exists
If (not Directory.DirectoryExists(lstrFileFolder)) Then
Directory.CreateDirectories(lstrFileFolder)
End If
'Save Uploaded file to server
lstrFileNamePath = lstrFileFolder & lstrFileName
loFile.PostedFile.SaveAs(lstrFileNamePath)
'Sets the answer
FileName.Text = lstrFileName
FileType.Text = loFile.PostedFile.ContentType
FileLength.Text = cStr(loFile.PostedFile.ContentLength)
FileUploadForm.visible = false
AnswerMsg.visible = true
End sub
</SCRIPT>
<BODY>
<ASP:panel id="FileUploadForm" visible="true" runat="server">
<form action="UploadFile.aspx" method="post"
enctype="multipart/form-data"
runat="server" ID=Form1>
<h1>ASP.NET File Upload Example</h1>
Select the File to Upload to the Server:<br>
<input id="loFile" type="file" runat="server"><br>
<input type="submit" value="Upload"
OnServerClick="UploadFile_Clicked"
runat="server"
ID=Submit1>
</form>
</ASP:panel>
<ASP:panel id="AnswerMsg" visible="false" runat="server">
Thanks your file <ASP:label id="FileName" runat="server" />
has been uploaded<BR>
We received <ASP:label id="FileLength" runat="server" />
bytes of the type <ASP:label id="FileType" runat="server" />
</ASP:panel>
</BODY>
</HTML>
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