FileUpload.FileBytes Eigenschaft

  • Referenz

Definition

Namespace:
System.Web.UI.WebControls
Assembly:
System.Web.dll

Ruft ein Array von Bytes in einer durch das FileUpload-Steuerelement angegebenen Datei ab.

public:
 property cli::array <System::Byte> ^ FileBytes { cli::array <System::Byte> ^ get(); };
[System.ComponentModel.Bindable(true)]
[System.ComponentModel.Browsable(false)]
public byte[] FileBytes { get; }
[<System.ComponentModel.Bindable(true)>]
[<System.ComponentModel.Browsable(false)>]
member this.FileBytes : byte[]
Public ReadOnly Property FileBytes As Byte()

Eigenschaftswert

Byte[]

Ein Byte-Array mit dem Inhalt der angegebenen Datei.

Attribute
BindableAttribute BrowsableAttribute

Ausnahmen

HttpException

Es wurde nicht die gesamte Datei gelesen.

Beispiele

Im folgenden Beispiel wird das Erstellen eines FileUpload Steuerelements veranschaulicht. Wenn der Benutzer auf die Schaltfläche Datei hochladen klickt, wird der Inhalt der Datei in einem Textfeld auf der Seite als Bytes angezeigt. In diesem Beispiel wird die FileBytes -Eigenschaft verwendet, um die gesamte Datei hochzuladen.

<%@ Page Language="C#" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head>
    <title>FileUpload.FileContent Property Example</title>
<script runat="server">
        
        private void DisplayFileContents(HttpPostedFile file) 
        {            
            int fileLen;
            string displayString = "";
            
            // 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 - 1];
            input = FileUpload1.FileBytes;
            
            // Copy the byte array to a string.
            for (int loop1 = 0; loop1 < fileLen; loop1++) {
                displayString = displayString + 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;
            
            // Add the textbox to the Controls collection
            // of the Placeholder control.
            PlaceHolder1.Controls.Add(ContentsTextBox);

        }

    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 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.";
            }
    }
</script>

</head>
<body>

    <h3>FileUpload.FileContent Property Example</h3>

    <form id="Form1" runat="server">
   
        <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>         
         
    </form>

</body>
</html>

<%@ Page Language="VB" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head>
    <title>FileUpload.FileContent Property Example</title>
<script runat="server">
        
        Sub UploadButton_Click(ByVal sender As Object, ByVal e As System.EventArgs)
            ' Specify the path on the server to
            ' save the uploaded file to.
            Dim savePath As String = "c:\temp\uploads\"
            
            ' Before attempting to perform operations
            ' on the file, verify that the FileUpload 
            ' control contains a file.
            If (FileUpload1.HasFile) Then
            
                ' 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."
            End If

        End Sub

        Sub DisplayFileContents(ByVal file As HttpPostedFile)
            
            Dim fileLen As Integer
            Dim displayString As String = ""
            
            ' 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.
            Dim Input(fileLen - 1) As Byte
            Input = FileUpload1.FileBytes
            
            ' Copy the byte array to a string.
            For loop1 As Integer = 0 To fileLen - 1
                displayString = displayString & Input(loop1).ToString()
            Next loop1
            
            ' Display the contents of the file in a 
            ' textbox on the page.
            ContentsLabel.Text = "The contents of the file as bytes:"
            
            Dim ContentsTextBox As New TextBox
            ContentsTextBox.TextMode = TextBoxMode.MultiLine
            ContentsTextBox.Height = Unit.Pixel(300)
            ContentsTextBox.Width = Unit.Pixel(400)
            ContentsTextBox.Text = displayString
            
            ' Add the textbox to the Controls collection
            ' of the Placeholder control.
            PlaceHolder1.Controls.Add(ContentsTextBox)

        End Sub

    </script>

</head>
<body>

    <h3>FileUpload.FileContent Property Example</h3>

    <form id="Form1" runat="server">
   
        <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>         
         
    </form>

</body>
</html>

Hinweise

Das FileUpload -Steuerelement liest die Datei nicht automatisch vom Client. Sie müssen explizit ein Steuerelement oder einen Mechanismus bereitstellen, damit der Benutzer die angegebene Datei übermitteln kann. Sie können beispielsweise eine Schaltfläche bereitstellen, auf die der Benutzer klicken kann, um die Datei hochzuladen. Der Code, den Sie zum Speichern der angegebenen Datei schreiben, könnte die FileBytes -Eigenschaft aufrufen, die den Inhalt der Datei zurückgibt.

Bevor Sie die FileBytes -Eigenschaft aufrufen, sollten Sie die HasFile -Eigenschaft verwenden, um zu überprüfen, ob das FileUpload Steuerelement eine Datei zum Hochladen enthält. Wenn zurückgibt HasFiletrue, rufen Sie die -Eigenschaft auf FileBytes . Wenn zurückgegeben wird false, wird dem Benutzer eine Meldung angezeigt, die angibt, dass das Steuerelement keine Datei enthält. Wenn Sie keinen Fehlerbehandlungscode bereitstellen, um zu überprüfen, ob eine Datei vorhanden ist, wird beim Versuch, eine nicht vorhandene Datei zu speichern, eine HttpException Ausnahme ausgelöst.

Gilt für:

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