好的,我在使用 DownloadDataAsync 并将字节返回给我时遇到了问题。这是我正在使用的代码:
private void button1_Click(object sender, EventArgs e)
{
byte[] bytes;
using (WebClient client = new WebClient())
{
client.DownloadProgressChanged += new DownloadProgressChangedEventHandler(DownloadProgressChanged);
bytes = client.DownloadDataAsync(new Uri("http://example.net/file.exe"));
}
}
void DownloadProgressChanged(object sender, DownloadProgressChangedEventArgs e)
{
double bytesIn = double.Parse(e.BytesReceived.ToString());
double totalBytes = double.Parse(e.TotalBytesToReceive.ToString());
double percentage = bytesIn / totalBytes * 100;
label1.Text = Math.Round(bytesIn / 1000) + " / " + Math.Round(totalBytes / 1000);
progressBar1.Value = int.Parse(Math.Truncate(percentage).ToString());
if (progressBar1.Value == 100)
{
MessageBox.Show("Download Completed");
button2.Enabled = true;
}
}
我得到的错误是“无法将类型‘void’隐式转换为‘byte[]’”
有没有办法让这成为可能,并在下载完成后给我字节数?删除“bytes =”时效果很好。
最佳答案
由于 DownloadDataAsync
方法是异步的,因此它不会立即返回结果。您需要处理 DownloadDataCompleted
事件:
client.DownloadDataCompleted += new DownloadDataCompletedEventHandler(DownloadCompleted);
...
private static void DownloadCompleted(Object sender, DownloadDataCompletedEventArgs e)
{
byte[] bytes = e.Result;
// do something with the bytes
}
关于C# WebClient 使用异步并返回数据,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/3474771/