WebClient.DownloadFileTaskAsync Method

Definition

Namespace:

System.Net

Assembly:

System.Net.WebClient.dll

Downloads the specified resource to a local file as an asynchronous operation using a task object. These methods do not block the calling thread.

Overloads

DownloadFileTaskAsync(String, String)	Downloads the specified resource to a local file as an asynchronous operation using a task object.
DownloadFileTaskAsync(Uri, String)	Downloads the specified resource to a local file as an asynchronous operation using a task object.

DownloadFileTaskAsync(String, String)

Source:

WebClient.cs

Downloads the specified resource to a local file as an asynchronous operation using a task object.

public:
 System::Threading::Tasks::Task ^ DownloadFileTaskAsync(System::String ^ address, System::String ^ fileName);

public System.Threading.Tasks.Task DownloadFileTaskAsync (string address, string fileName);

member this.DownloadFileTaskAsync : string * string -> System.Threading.Tasks.Task

Public Function DownloadFileTaskAsync (address As String, fileName As String) As Task

Parameters

address

String

The URI of the resource to download.

fileName

String

The name of the file to be placed on the local computer.

Returns

Task

The task object representing the asynchronous operation.

Exceptions

ArgumentNullException

The address parameter is null.

-or-

The fileName parameter is null.

WebException

The URI formed by combining BaseAddress and address is invalid.

-or-

An error occurred while downloading the resource.

InvalidOperationException

The local file specified by fileName is in use by another thread.

Remarks

Caution

WebRequest, HttpWebRequest, ServicePoint, and WebClient are obsolete, and you shouldn't use them for new development. Use HttpClient instead.

This operation will not block. The returned Task object will complete after the data resource has been downloaded.

This method downloads the resource at the URI specified by in the address parameter. When the download completes successfully, the downloaded file is named fileName on the local computer. The file is downloaded asynchronously using thread resources that are automatically allocated from the thread pool.

In .NET Framework and .NET Core 1.0, you can cancel asynchronous operations that have not completed by calling the CancelAsync method.

If the BaseAddress property is not an empty string ("") and address does not specify 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 in .NET Framework.

When using this method in an ASP.NET page, you will receive an error if the account that the page executes under does not have permission to access the local file.

DownloadFileTaskAsync(Uri, String)

Source:

WebClient.cs

Downloads the specified resource to a local file as an asynchronous operation using a task object.

public:
 System::Threading::Tasks::Task ^ DownloadFileTaskAsync(Uri ^ address, System::String ^ fileName);

public System.Threading.Tasks.Task DownloadFileTaskAsync (Uri address, string fileName);

member this.DownloadFileTaskAsync : Uri * string -> System.Threading.Tasks.Task

Public Function DownloadFileTaskAsync (address As Uri, fileName As String) As Task

Parameters

address

Uri

The URI of the resource to download.

fileName

String

The name of the file to be placed on the local computer.

Returns

Task

The task object representing the asynchronous operation.

Exceptions

ArgumentNullException

The address parameter is null.

-or-

The fileName parameter is null.

WebException

The URI formed by combining BaseAddress and address is invalid.

-or-

An error occurred while downloading the resource.

InvalidOperationException

The local file specified by fileName is in use by another thread.

Remarks

Caution

WebRequest, HttpWebRequest, ServicePoint, and WebClient are obsolete, and you shouldn't use them for new development. Use HttpClient instead.

This operation will not block. The returned Task object will complete after the data resource has been downloaded.

This method downloads the resource at the URI specified by in the address parameter. When the download completes successfully, the downloaded file is named fileName on the local computer. The file is downloaded asynchronously using thread resources that are automatically allocated from the thread pool.

In .NET Framework and .NET Core 1.0, you can cancel asynchronous operations that have not completed by calling the CancelAsync method.

If the BaseAddress property is not an empty string ("") and address does not specify 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 in .NET Framework.

When using this method in an ASP.NET page, you will receive an error if the account that the page executes under does not have permission to access the local file.