DownloadDataCompletedEventArgs クラスとは何？わかりやすく解説 Weblio辞書

.NET Framework クラスライブラリリファレンス

索引トップ用語の索引ランキング

DownloadDataCompletedEventArgs クラス

メモ : このクラスは、.NET Framework version 2.0 で新しく追加されたものです。

DownloadDataCompleted イベントのデータを提供します。

名前空間: System.Net
アセンブリ: System (system.dll 内)
構文

Visual Basic (宣言)

Public Class DownloadDataCompletedEventArgs
    Inherits AsyncCompletedEventArgs

Visual Basic (使用法)

Dim instance As DownloadDataCompletedEventArgs

public class DownloadDataCompletedEventArgs
 : AsyncCompletedEventArgs

C++

public ref class DownloadDataCompletedEventArgs
 : public AsyncCompletedEventArgs

public class DownloadDataCompletedEventArgs
 extends AsyncCompletedEventArgs

JScript

public class DownloadDataCompletedEventArgs
 extends AsyncCompletedEventArgs

解説

このクラスのインスタンスは DownloadDataCompletedEventHandler に渡されます。

使用例

ユーザー指定のリソースをダウンロードするコード例を次に示します。

Visual Basic

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

    Dim waiter As System.Threading.AutoResetEvent
 = New System.Threading.AutoResetEvent(False)
    Dim client As WebClient = New
 WebClient()

    '  Specify that the DownloadDataCallback method gets called
    '  when the download completes.
    AddHandler client.DownloadDataCompleted, AddressOf
 DownloadDataCallback
                Dim uri as Uri = New
 Uri(address)
    client.DownloadDataAsync(uri, waiter)

    '  Block the main application thread. Real applications
    '  can perform other tasks while waiting for the download to complete.
    waiter.WaitOne()
End Sub

// Sample call : DownLoadDataInBackground ("http://www.contoso.com/GameScores.html");
public static void DownloadDataInBackground
 (string address)
{
    System.Threading.AutoResetEvent waiter = new System.Threading.AutoResetEvent
 (false);
    WebClient client = new WebClient ();
    Uri uri = new Uri(address);

    // Specify that the DownloadDataCallback method gets called
    // when the download completes.
    client.DownloadDataCompleted += new DownloadDataCompletedEventHandler
 (DownloadDataCallback);
    client.DownloadDataAsync (uri, waiter);

    // Block the main application thread. Real applications
    // can perform other tasks while waiting for the download to complete.
    waiter.WaitOne ();
}

ダウンロードが完了すると次のメソッドが呼び出されます。

Visual Basic

Public Shared Sub DownloadDataCallback(ByVal
 sender As Object, ByVal
 e As DownloadDataCompletedEventArgs)

    Dim waiter As System.Threading.AutoResetEvent
 = CType(e.UserState, System.Threading.AutoResetEvent)

    Try

        '  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 data() As Byte
 = CType(e.Result, Byte())
            Dim textData As String
 = System.Text.Encoding.UTF8.GetString(data)

            Console.WriteLine(textData)
        End If
    Finally

        '  Let the main application thread resume.
        waiter.Set()
    End Try
End Sub

public static void DownloadDataCallback
 (Object sender, DownloadDataCompletedEventArgs e)
{
    System.Threading.AutoResetEvent waiter = (System.Threading.AutoResetEvent)e.UserState;

    try
    {
        // If the request was not canceled and did not throw
        // an exception, display the resource.
        if (!e.Cancelled && e.Error == null)
        {
            byte[] data = (byte[])e.Result;
            string textData = System.Text.Encoding.UTF8.GetString
 (data);

            Console.WriteLine (textData);
        }
    }
    finally
    {
        // Let the main application thread resume.
        waiter.Set ();
    }
}