OpenWriteCompletedEventArgs 类

定义

命名空间:

System.Net

程序集:

System.Net.WebClient.dll

Source:

WebClient.cs

为 OpenWriteCompleted 事件提供数据。

public ref class OpenWriteCompletedEventArgs : System::ComponentModel::AsyncCompletedEventArgs

public class OpenWriteCompletedEventArgs : System.ComponentModel.AsyncCompletedEventArgs

type OpenWriteCompletedEventArgs = class
    inherit AsyncCompletedEventArgs

Public Class OpenWriteCompletedEventArgs
Inherits AsyncCompletedEventArgs

继承

Object

EventArgs

AsyncCompletedEventArgs

OpenWriteCompletedEventArgs

示例

下面的代码示例演示如何打开流以写入要上传的数据。

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

   // Specify that the OpenWriteCallback method gets called
   // when the writeable stream is available.
   client->OpenWriteCompleted += gcnew OpenWriteCompletedEventHandler( OpenWriteCallback2 );
   client->OpenWriteAsync( uri );

   // Applications can perform other tasks
   // while waiting for the upload to complete.
}

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

    // Specify that the OpenWriteCallback method gets called
    // when the writeable stream is available.
    client.OpenWriteCompleted += new OpenWriteCompletedEventHandler(OpenWriteCallback2);
    client.OpenWriteAsync(uri);
    // Applications can perform other tasks
    // while waiting for the upload to complete.
}

Public Shared Sub OpenResourceForPosting(ByVal address As String)

    Dim client As WebClient = New WebClient()
    '  Specify that the OpenWriteCallback method gets called
    '  when the writeable stream is available.
    AddHandler client.OpenWriteCompleted, AddressOf OpenWriteCallback2
                Dim uri as Uri = New Uri(address)
    client.OpenWriteAsync(uri)
    '  Applications can perform other tasks
    '  while waiting for the upload to complete.
End Sub

当流可用时，将调用以下方法。

void OpenWriteCallback2( Object^ /*sender*/, OpenWriteCompletedEventArgs^ e )
{
   Stream^ body = nullptr;
   StreamWriter^ s = nullptr;
   try
   {
      body = dynamic_cast<Stream^>(e->Result);
      s = gcnew StreamWriter( body );
      s->AutoFlush = true;
      s->Write( "This is content data to be sent to the server." );
   }
   finally
   {
      if ( s != nullptr )
      {
         s->Close();
      }
      if ( body != nullptr )
      {
         body->Close();
      }
   }

}

private static void OpenWriteCallback2(Object sender, OpenWriteCompletedEventArgs e)
{
    Stream body = null;
    StreamWriter s = null;

    try
    {
        body = (Stream)e.Result;
        s = new StreamWriter(body);
        s.AutoFlush = true;
        s.Write("This is content data to be sent to the server.");
    }
    finally
    {
        if (s != null)
        {
            s.Close();
        }

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

Private Shared Sub OpenWriteCallback2(ByVal sender As Object, ByVal e As OpenWriteCompletedEventArgs)

    Dim body As Stream = Nothing
    Dim s As StreamWriter = Nothing

    Try

        body = CType(e.Result, Stream)
        s = New StreamWriter(body)
        s.AutoFlush = True
        s.Write("This is content data to be sent to the server.")
    Finally

        If Not s Is Nothing Then

            s.Close()
        End If

        If Not body Is Nothing Then

            body.Close()
        End If
    End Try
End Sub

注解

此类的实例将 OpenWriteCompletedEventHandler 传递给 方法。

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	获取用于向服务器发送数据的可写流。
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)