WebClient.DownloadStringAsync Method

Definition

Namespace:

System.Net

Assembly:

System.Net.WebClient.dll

Downloads the resource specified as a String or a Uri. These methods do not block the calling thread.

Overloads

DownloadStringAsync(Uri)	Downloads the resource specified as a Uri. This method does not block the calling thread.
DownloadStringAsync(Uri, Object)	Downloads the specified string to the specified resource. This method does not block the calling thread.

DownloadStringAsync(Uri)

Source:

WebClient.cs

Downloads the resource specified as a Uri. This method does not block the calling thread.

public:
 void DownloadStringAsync(Uri ^ address);

public void DownloadStringAsync (Uri address);

member this.DownloadStringAsync : Uri -> unit

Public Sub DownloadStringAsync (address As Uri)

Parameters

address

Uri

A Uri containing the URI to download.

Exceptions

ArgumentNullException

The address parameter is null.

WebException

The URI formed by combining BaseAddress and address is invalid.

-or-

An error occurred while downloading the resource.

Remarks

Caution

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

The resource is downloaded asynchronously using thread resources that are automatically allocated from the thread pool.

After downloading the resource, this method uses the encoding specified in the Encoding property to convert the resource to a String. This method does not block the calling thread while downloading the resource. To download a resource and block while waiting for the server's response, use the DownloadString method. When the download completes, the DownloadStringCompleted event is raised. Your application must handle this event to receive notification. The downloaded string is available in the Result property.

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 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 in .NET Framework.

This method stores in the task it returns all non-usage exceptions that the method's synchronous counterpart can throw. If an exception is stored into the returned task, that exception will be thrown when the task is awaited. Usage exceptions, such as ArgumentException, are still thrown synchronously. For the stored exceptions, see the exceptions thrown by DownloadString(Uri).

DownloadStringAsync(Uri, Object)

Source:

WebClient.cs

Downloads the specified string to the specified resource. This method does not block the calling thread.

public:
 void DownloadStringAsync(Uri ^ address, System::Object ^ userToken);

public void DownloadStringAsync (Uri address, object? userToken);

member this.DownloadStringAsync : Uri * obj -> unit

Public Sub DownloadStringAsync (address As Uri, userToken As Object)

Parameters

address

Uri

A Uri containing the URI to download.

userToken

Object

A user-defined object that is passed to the method invoked when the asynchronous operation completes.

Exceptions

ArgumentNullException

The address parameter is null.

WebException

The URI formed by combining BaseAddress and address is invalid.

-or-

An error occurred while downloading the resource.

Remarks

Caution

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

The resource is downloaded asynchronously using thread resources that are automatically allocated from the thread pool.

After downloading the resource, this method uses the encoding specified in the Encoding property to convert the resource to a String. This method does not block the calling thread while downloading the resource. To download a resource and block while waiting for the server's response, use the DownloadString method. When the download completes, the DownloadStringCompleted event is raised. Your application must handle this event to receive notification. The downloaded string is available in the Result property.

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 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 in .NET Framework.