Technical topic: server controls-File Upload

Note: I have read the tutorial of Dai Ge and raised a few questions, which can be discussed below:

Step 1:Create a website in the following language: Visual C #. A file named default. aspx and default. aspx. CS is generated;

Step 2:Create an up folder and an upfile folder in the same directory of the default. aspx file to store the uploaded files;

Step 3:In the design view of the default. aspx. aspx file, drag the server control 4 from the toolbox,
They are: fileupload, button, image, and label;

Step 4:Arrange various controls according to your preferences, and expand the display areas of the image and label controls;

Step 5:Change the text attribute of the label control to a null value, and change the text attribute of the button control to "Upload ";

Step 6:Change the ID attribute of the four controls to: upfileupload1, upbutton1, upimage1, and uplabel1;
That is, with "up", we need to develop the habit of ID change;

Step 7:In the design view of the default. aspx. aspx file, double-click the button control to go to programming,CodeAs follows:

Protected   Void Upbutton1_click ( Object Sender, eventargs E)
{
String Name = Upfileupload1.filename; // Get the name of the uploaded folder
String Size = Upfileupload1.postedfile. contentlength. tostring (); // Obtains the size of the uploaded folder.
String Type = Name. substring (name. lastindexof ( " . " ) +   1 ); // Get the file suffix

String Ipath = Server. mappath ( " Up " ) +   " \\ "   + Name; // Get the actual path of folder upload
String Fpath = Server. mappath ( " Upfile " ) +   " \\ "   + Name; // Get the actual path of folder upload
String Wpath =   " Up \\ "   + Name; // Virtual Path written to the database

// Next we need to determine the file format
If (Type =   " JPG "   | Type =   " GIF "   | Type =   " BMP "   | Type =   " PNG " )
{
Upimage1.visible =   True ;
Upfileupload1.saveas (ipath ); // Save the file to the path
Upimage1.imageurl = Wpath; // Display the image
Uplabel1.text =   " The file name you passed is: "   + Name +   " <Br> the file size is: "   + Size +   " Byte <br> the file type is: "   + Type +   " <Br> the suffix is: "   + Type +   " <Br> the actual path is: "   + Ipath +   " <Br> the virtual path is: "   + Wpath;
}
Else
{
Upimage1.visible =   False ; // Hide the image control, otherwise it will show a small xx
Upfileupload1.saveas (fpath ); // Save the folder in another folder
Uplabel1.text =   " The file name you passed is: "   + Name +   " <Br> the file size is: "   + Size +   " Byte <br> the file type is: "   + Type +   " <Br> the suffix is: "   + Type +   " <Br> the actual path is: "   + Ipath +   " <Br> the virtual path is: "   + Wpath;
}
}

Step 8:Add the following code to page_load:

Protected   Void Page_load ( Object Sender, eventargs E)
{
If ( ! This . Ispostback)
{
Upimage1.visible =   False ; // Hide the image control, otherwise it will show a small xx
}
}

Step 9:OK. Start debugging.

For more information, see:

· Upload multiple files at the same time
· The file suffix is lower-case and can be uploaded, for example, JPG, GIF, BMP, and PNG files. However, if the file suffix is upper-case, it will not work.
· How can I solve the problem of file name duplication when there are too many files uploaded?
· How to prevent malicious attacks