OpenWriteCompletedEventHandler 委托

定义

命名空间:

System.Net

程序集:

netstandard.dll, System.Net.WebClient.dll

表示将用来处理 OpenWriteCompleted 的 WebClient 事件的方法。

C#

public delegate void OpenWriteCompletedEventHandler(object sender, OpenWriteCompletedEventArgs e);

参数

sender

Object

事件源。

e

OpenWriteCompletedEventArgs

一个包含事件数据的 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。

C#

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.
}

当流可用时，将调用以下方法。

C#

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();
        }
    }
}

注解

创建 OpenWriteCompletedEventHandler 委托时，需要标识将处理该事件的方法。 若要将事件与事件处理程序关联，请将该委托的一个实例添加到事件中。 除非移除了该委托，否则每当发生该事件时就会调用事件处理程序。

扩展方法

GetMethodInfo(Delegate)

获取指示指定委托表示的方法的对象。

适用于