DownloadStringCompletedEventArgs 类

定义

命名空间:

System.Net

程序集:

System.Net.WebClient.dll

Source:

WebClient.cs

为 DownloadStringCompleted 事件提供数据。

public ref class DownloadStringCompletedEventArgs : System::ComponentModel::AsyncCompletedEventArgs

public class DownloadStringCompletedEventArgs : System.ComponentModel.AsyncCompletedEventArgs

type DownloadStringCompletedEventArgs = class
    inherit AsyncCompletedEventArgs

Public Class DownloadStringCompletedEventArgs
Inherits AsyncCompletedEventArgs

继承

Object

EventArgs

AsyncCompletedEventArgs

DownloadStringCompletedEventArgs

示例

下面的代码示例演示如何异步下载字符串。

// Sample call : DownloadStringInBackground2 ("http://www.contoso.com/GameScores.html");
void DownloadStringInBackground2( String^ address )
{
   WebClient^ client = gcnew WebClient;
   Uri ^uri = gcnew Uri(address);

   // Specify that the DownloadStringCallback2 method gets called
   // when the download completes.
   client->DownloadStringCompleted += gcnew DownloadStringCompletedEventHandler( DownloadStringCallback2 );
   client->DownloadStringAsync( uri );
}

// Sample call : DownloadStringInBackground2 ("http://www.contoso.com/GameScores.html");
public static void DownloadStringInBackground2(string address)
{
    WebClient client = new WebClient();
    Uri uri = new Uri(address);

    // Specify that the DownloadStringCallback2 method gets called
    // when the download completes.
    client.DownloadStringCompleted += new DownloadStringCompletedEventHandler(DownloadStringCallback2);
    client.DownloadStringAsync(uri);
}

'  Sample call : DownloadStringInBackground2 ("http:' www.contoso.com/GameScores.html")
Public Shared Sub DownloadStringInBackground2(ByVal address As String)

    Dim client As WebClient = New WebClient()

    '  Specify that the DownloadStringCallback2 method gets called
    '  when the download completes.
    AddHandler client.DownloadStringCompleted, AddressOf DownloadStringCallback2
                Dim uri as Uri = New Uri(address)
    client.DownloadStringAsync(uri)
End Sub

下载完成后，将调用以下方法。

void DownloadStringCallback2( Object^ /*sender*/, DownloadStringCompletedEventArgs^ e )
{

   // If the request was not canceled and did not throw
   // an exception, display the resource.
   if (  !e->Cancelled && e->Error == nullptr )
   {
      String^ textString = dynamic_cast<String^>(e->Result);
      Console::WriteLine( textString );
   }
}

private static void DownloadStringCallback2(Object sender, DownloadStringCompletedEventArgs e)
{
    // If the request was not canceled and did not throw
    // an exception, display the resource.
    if (!e.Cancelled && e.Error == null)
    {
        string textString = (string)e.Result;

        Console.WriteLine(textString);
    }
}

Private Shared Sub DownloadStringCallback2(ByVal sender As Object, ByVal e As DownloadStringCompletedEventArgs)

    '  If the request was not canceled and did not throw
    '  an exception, display the resource.
    If e.Cancelled = False AndAlso e.Error Is Nothing Then

        Dim textString As String = CStr(e.Result)
        Console.WriteLine(textString)
    End If
End Sub

注解

此类的实例将传递给 DownloadStringCompletedEventHandler。

属性

Cancelled	获取一个值，该值指示异步操作是否已被取消。 (继承自 AsyncCompletedEventArgs)
Error	获取一个值，该值指示异步操作期间发生的错误。 (继承自 AsyncCompletedEventArgs)
Result	获取由 DownloadStringAsync 方法下载的数据。
UserState	获取异步任务的唯一标识符。 (继承自 AsyncCompletedEventArgs)

方法

Equals(Object)	确定指定对象是否等于当前对象。 (继承自 Object)
GetHashCode()	作为默认哈希函数。 (继承自 Object)
GetType()	获取当前实例的 Type。 (继承自 Object)
MemberwiseClone()	创建当前 Object 的浅表副本。 (继承自 Object)
RaiseExceptionIfNecessary()	如果异步操作失败，则引发用户提供的异常。 (继承自 AsyncCompletedEventArgs)
ToString()	返回表示当前对象的字符串。 (继承自 Object)