OpenReadCompletedEventArgs Class

Definition

OpenReadCompleted 事件提供数据。Provides data for the OpenReadCompleted event.

public ref class OpenReadCompletedEventArgs : System::ComponentModel::AsyncCompletedEventArgs
public class OpenReadCompletedEventArgs : System.ComponentModel.AsyncCompletedEventArgs
type OpenReadCompletedEventArgs = class
    inherit AsyncCompletedEventArgs
Public Class OpenReadCompletedEventArgs
Inherits AsyncCompletedEventArgs
Inheritance
OpenReadCompletedEventArgs

Examples

下面的代码示例演示如何下载资源以进行读取。The following code example demonstrates downloading a resource for reading.

void OpenResourceForReading2( String^ address )
{
   WebClient^ client = gcnew WebClient;
   Uri ^uri = gcnew Uri(address);

   client->OpenReadCompleted += gcnew OpenReadCompletedEventHandler( OpenReadCallback2 );
   client->OpenReadAsync( uri );
}


public static void OpenResourceForReading2 (string address)
{
    WebClient client = new WebClient ();
    Uri uri = new Uri(address);

    client.OpenReadCompleted += new OpenReadCompletedEventHandler(OpenReadCallback2);
    client.OpenReadAsync (uri);
}

Public Shared Sub OpenResourceForReading2(ByVal address As String)

    Dim client As WebClient = New WebClient()
    AddHandler client.OpenReadCompleted, AddressOf OpenReadCallback2
                Dim uri as Uri = New Uri(address)
    client.OpenReadAsync(uri)                        
End Sub

下载完成时,将调用以下方法。The following method is called when the download completes.

void OpenReadCallback2( Object^ /*sender*/, OpenReadCompletedEventArgs^ e )
{
   Stream^ reply = nullptr;
   StreamReader^ s = nullptr;
   try
   {
      reply = dynamic_cast<Stream^>(e->Result);
      s = gcnew StreamReader( reply );
      Console::WriteLine( s->ReadToEnd() );
   }
   finally
   {
      if ( s != nullptr )
      {
         s->Close();
      }
      if ( reply != nullptr )
      {
         reply->Close();
      }
   }

}


private static void OpenReadCallback2 (Object sender, OpenReadCompletedEventArgs e)
{
    Stream reply = null;
    StreamReader s = null;

    try
    {
        reply = (Stream)e.Result;
        s = new StreamReader (reply);
        Console.WriteLine (s.ReadToEnd ());
    }
    finally
    {
        if (s != null)
        {
            s.Close ();
        }

        if (reply != null)
        {
            reply.Close ();
        }
    }
}

Private Shared Sub OpenReadCallback2(ByVal sender As Object, ByVal e As OpenReadCompletedEventArgs)

    Dim reply As Stream = Nothing
    Dim s As StreamReader = Nothing

    Try

        reply = CType(e.Result, Stream)
        s = New StreamReader(reply)
        Console.WriteLine(s.ReadToEnd())
    Finally

        If Not s Is Nothing Then

            s.Close()
        End If

        If Not reply Is Nothing Then

            reply.Close()
        End If
    End Try
End Sub

Remarks

此类的实例将传递给 OpenReadCompletedEventHandler 方法。Instances of this class are passed to OpenReadCompletedEventHandler methods.

Properties

Cancelled

获取一个值,该值指示异步操作是否已被取消。Gets a value indicating whether an asynchronous operation has been canceled.

(Inherited from AsyncCompletedEventArgs)
Error

获取一个值,该值指示异步操作期间发生的错误。Gets a value indicating which error occurred during an asynchronous operation.

(Inherited from AsyncCompletedEventArgs)
Result

获取可读流,该可读流包含由 DownloadDataAsync 方法下载的数据。Gets a readable stream that contains data downloaded by a DownloadDataAsync method.

UserState

获取异步任务的唯一标识符。Gets the unique identifier for the asynchronous task.

(Inherited from AsyncCompletedEventArgs)

Methods

Equals(Object)

确定指定的对象是否等于当前对象。Determines whether the specified object is equal to the current object.

(Inherited from Object)
GetHashCode()

作为默认哈希函数。Serves as the default hash function.

(Inherited from Object)
GetType()

获取当前实例的 TypeGets the Type of the current instance.

(Inherited from Object)
MemberwiseClone()

创建当前 Object 的浅表副本。Creates a shallow copy of the current Object.

(Inherited from Object)
RaiseExceptionIfNecessary()

如果异步操作失败,则引发用户提供的异常。Raises a user-supplied exception if an asynchronous operation failed.

(Inherited from AsyncCompletedEventArgs)
ToString()

返回表示当前对象的字符串。Returns a string that represents the current object.

(Inherited from Object)

Applies to