WebClient.DownloadFile Method (String, String) (System.Net)

DownloadFile Method (String, String...

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Microsoft Visual Studio 2008/.NET Framework 3.5

Other versions are also available for the following:

.NET Framework Class Library

WebClient..::.DownloadFile Method (String, String)

Downloads the resource with the specified URI to a local file.

Namespace: System.Net
Assembly: System (in System.dll)

Syntax

Visual Basic (Declaration)

Public Sub DownloadFile ( _
    address As String, _
    fileName As String _
)

Visual Basic (Usage)

Dim instance As WebClient
Dim address As String
Dim fileName As String

instance.DownloadFile(address, fileName)

public void DownloadFile(
    string address,
    string fileName
)

Visual C++

public:
void DownloadFile(
    String^ address, 
    String^ fileName
)

JScript

public function DownloadFile(
    address : String, 
    fileName : String
)

Parameters

address: Type: System..::.String
The URI from which to download data.

fileName: Type: System..::.String
The name of the local file that is to receive the data.

Exceptions

Exception	Condition
WebException	The URI formed by combining BaseAddress and address is invalid. -or- filename is nullNothingnullptra null reference (Nothing in Visual Basic) or Empty. -or- The file does not exist. -or- An error occurred while downloading data.
NotSupportedException	The method has been called simultaneously on multiple threads.

Exception

Condition

WebException

The URI formed by combining BaseAddress and address is invalid.

-or-

filename is nullNothingnullptra null reference (Nothing in Visual Basic) or Empty.

-or-

The file does not exist.

-or- An error occurred while downloading data.

NotSupportedException

The method has been called simultaneously on multiple threads.

Remarks

The DownloadFile method downloads to a local file data from the URI specified by in the address parameter. This method blocks while downloading the resource. To download a resource and continue executing while waiting for the server's response, use one of the DownloadFileAsync methods.

If the BaseAddress property is not an empty string ("") and address does not contain an absolute URI, address must be a relative URI that is combined with BaseAddress to form the absolute URI of the requested data. If the QueryString property is not an empty string, it is appended to address.

This method uses the RETR command to download an FTP resource. For an HTTP resource, the GET method is used.

Note:
This member outputs trace information when you enable network tracing in your application. For more information, see Network Tracing.

When using this method in a middle tier application, such as an ASP.NET page, you will receive an error if the account under which the application executes does not have permission to access the file.

Examples

The following code example downloads a file from http://www.contoso.com to the local hard drive.

Visual Basic

Dim remoteUri As String = "http://www.contoso.com/library/homepage/images/"
Dim fileName As String = "ms-banner.gif"
Dim myStringWebResource As String = Nothing
' Create a new WebClient instance.
Dim myWebClient As New WebClient()
' Concatenate the domain with the Web resource filename. Because DownloadFile 
'requires a fully qualified resource name, concatenate the domain with the Web resource file name.
myStringWebResource = remoteUri + fileName
Console.WriteLine("Downloading File ""{0}"" from ""{1}"" ......." + ControlChars.Cr + ControlChars.Cr, fileName, myStringWebResource)
' The DownloadFile() method downloads the Web resource and saves it into the current file-system folder.
myWebClient.DownloadFile(myStringWebResource, fileName)
Console.WriteLine("Successfully Downloaded file ""{0}"" from ""{1}""", fileName, myStringWebResource)
Console.WriteLine((ControlChars.Cr + "Downloaded file saved in the following file system folder:" + ControlChars.Cr + ControlChars.Tab + Application.StartupPath))

            string remoteUri = "http://www.contoso.com/library/homepage/images/";
            string fileName = "ms-banner.gif", myStringWebResource = null;
            // Create a new WebClient instance.
            WebClient myWebClient = new WebClient();
            // Concatenate the domain with the Web resource filename.
            myStringWebResource = remoteUri + fileName;
            Console.WriteLine("Downloading File \"{0}\" from \"{1}\" .......\n\n", fileName, myStringWebResource);
            // Download the Web resource and save it into the current filesystem folder.
            myWebClient.DownloadFile(myStringWebResource,fileName);        
            Console.WriteLine("Successfully Downloaded File \"{0}\" from \"{1}\"", fileName, myStringWebResource);
            Console.WriteLine("\nDownloaded file saved in the following file system folder:\n\t" + Application.StartupPath);

Visual C++

String^ remoteUri = "http://www.contoso.com/library/homepage/images/";
String^ fileName = "ms-banner.gif", ^myStringWebResource = nullptr;
// Create a new WebClient instance.
WebClient^ myWebClient = gcnew WebClient;
// Concatenate the domain with the Web resource filename.
myStringWebResource = String::Concat( remoteUri, fileName );
Console::WriteLine( "Downloading File \"{0}\" from \"{1}\" .......\n\n", fileName, myStringWebResource );
// Download the Web resource and save it into the current filesystem folder.
myWebClient->DownloadFile( myStringWebResource, fileName );
Console::WriteLine( "Successfully Downloaded File \"{0}\" from \"{1}\"", fileName, myStringWebResource );
Console::WriteLine( "\nDownloaded file saved in the following file system folder:\n\t {0}", Application::StartupPath );

CPP_OLD

String* remoteUri = S"http://www.contoso.com/library/homepage/images/";
String* fileName = S"ms-banner.gif", * myStringWebResource = 0;
// Create a new WebClient instance.
WebClient* myWebClient = new WebClient();
// Concatenate the domain with the Web resource filename.
myStringWebResource = String::Concat(remoteUri, fileName);
Console::WriteLine(S"Downloading File \" {0}\" from \" {1}\" .......\n\n", fileName, myStringWebResource);
   // Download the Web resource and save it into the current filesystem folder.
   myWebClient->DownloadFile(myStringWebResource, fileName);
Console::WriteLine(S"Successfully Downloaded File \" {0}\" from \" {1}\"", fileName, myStringWebResource);
   Console::WriteLine(S"\nDownloaded file saved in the following file system folder:\n\t {0}", Application::StartupPath);

.NET Framework Security

FileIOPermission
to write the file fileName. Associated enumeration: Write.

Platforms

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Version Information

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0

Reference

WebClient Class

WebClient Members

DownloadFile Overload

System.Net Namespace