如何传递使用 webclient 异步下载的对象？

Question

我正在尝试异步下载 Json 类型的数据。（我知道如何传递 uri，但不会 how/where 下载它。）

编辑，我使用的是 .NET 3.5

遇到以下情况如何操作：

using (var client = new System.Net.WebClient())

var downloaded;

{
    client.DownloadDataAsync(myUri, downloaded);
}

Console.WriteLine(downloaded);

Answer 1

如果您使用的是 .NET Framework 3.5，此示例代码应该可以帮助您前进

static void Main(string[] args)
{
    Uri myUri = new Uri("http://google.com");

    using (System.Net.WebClient client = new System.Net.WebClient())
    {
        client.DownloadStringCompleted += Client_DownloadStringCompleted; 

        // the WebClient is NOT thread safe so you cannot make concurrent calls
        client.DownloadStringAsync(myUri);

        // if you need to wait for the operation to finish
        //while (client.IsBusy)
        //{
        //    System.Threading.Thread.Sleep(100);
        //}
    }

    Console.WriteLine("Done");
    Console.ReadLine();
}

private static void Client_DownloadStringCompleted(object sender, DownloadStringCompletedEventArgs e)
{
   System.IO.File.WriteAllText(Path.GetTempFileName(), e.Result);
}

但是，如果您可以使用较新版本的 .NET 或 .NET Core，我建议您使用 HttpClient

using (var client = new System.Net.Http.HttpClient())
{
    var response = await client.GetAsync(myUri);
    var json = await response.Content.ReadAsStringAsync();

    // to download as a byte array and save locally:
    //      var bytes = await response.Content.ReadAsByteArrayAsync();
    //      System.IO.File.WriteAllBytes("YourPath", bytes);
}

如何传递使用 webclient 异步下载的对象？

How do I pass the object downloaded asynchronously using webclient?

c#

asynchronous

webclient

http

download