https://msdn.microsoft.com/zh-cn/library/system.web.ui.webcontrols.fileupload.postedfile.aspx
<%@ Page Language="C#" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <script runat="server"> protected void UploadButton_Click(object sender, EventArgs e) { // Specify the path on the server to // save the uploaded file to. String savePath = @"c:\temp\uploads\"; // Before attempting to perform operations // on the the file, verify that the FileUpload // control contains a file. if (FileUpload1.HasFile) { // Append the name of the file to upload to the path. savePath += FileUpload1.FileName; // Call the SaveAs method to save the // uploaded file to the specified path. // This example does not perform all // the necessary error checking. // If a file with the same name // already exists in the specified path, // the uploaded file overwrites it. FileUpload1.SaveAs(savePath); // Notify the user that the file was uploaded successfully. UploadStatusLabel.Text = "Your file was uploaded successfully."; // Call a helper routine to display the contents // of the file to upload. DisplayFileContents(FileUpload1.PostedFile); } else { // Notify the user that a file was not uploaded. UploadStatusLabel.Text = "You did not specify a file to upload."; } } void DisplayFileContents(HttpPostedFile file) { System.IO.Stream myStream; Int32 fileLen; StringBuilder displayString = new StringBuilder(); // Get the length of the file. fileLen = FileUpload1.PostedFile.ContentLength; // Display the length of the file in a label. LengthLabel.Text = "The length of the file is " + fileLen.ToString() + " bytes."; // Create a byte array to hold the contents of the file. Byte[] Input = new Byte[fileLen]; // Initialize the stream to read the uploaded file. myStream = FileUpload1.FileContent; // Read the file into the byte array. myStream.Read(Input, 0, fileLen); // Copy the byte array to a string. for (int loop1 = 0; loop1 < fileLen; loop1++) { displayString.Append(Input[loop1].ToString()); } // Display the contents of the file in a // textbox on the page. ContentsLabel.Text = "The contents of the file as bytes:"; TextBox ContentsTextBox = new TextBox(); ContentsTextBox.TextMode = TextBoxMode.MultiLine; ContentsTextBox.Height = Unit.Pixel(300); ContentsTextBox.Width = Unit.Pixel(400); ContentsTextBox.Text = displayString.ToString(); // Add the textbox to the Controls collection // of the Placeholder control. PlaceHolder1.Controls.Add(ContentsTextBox); } </script> <html xmlns="http://www.w3.org/1999/xhtml" > <head runat="server"> <title>FileUpload.FileContent Property Example</title> </head> <body> <form id="form1" runat="server"> <div> <h4>Select a file to upload:</h4> <asp:FileUpload id="FileUpload1" runat="server"> </asp:FileUpload> <br /><br /> <asp:Button id="UploadButton" Text="Upload file" OnClick="UploadButton_Click" runat="server"> </asp:Button> <br /><br /> <asp:Label id="UploadStatusLabel" runat="server"> </asp:Label> <hr /> <asp:Label id="LengthLabel" runat="server"> </asp:Label> <br /><br /> <asp:Label id="ContentsLabel" runat="server"> </asp:Label> <br /><br /> <asp:PlaceHolder id="PlaceHolder1" runat="server"> </asp:PlaceHolder> </div> </form> </body> </html>