如何使用WebClients SYNCHRONOUS DownloadString函数而不阻塞UI？

Question

我试着在一个单独的非ui线程上下载一个字符串，当它下载完成后更新ui，但我想在不冻结ui的情况下做这件事，所以我试着做一个线程，但这不起作用，然后我试图在那个线程中做一个线程，但也不起作用，我如何调用downloadstring函数而不冻结ui呢？

public partial class Form1 : Form
{
    private delegate void displayDownloadDelegate(string content);
    public Thread downloader, web;
    public Form1()
    {
        InitializeComponent();
    }
    // Go (Download string from URL) button
    private void button1_Click(object sender, EventArgs e)
    {
        textBox1.Enabled = false;

        string url = textBox1.Text;
        Thread web = new Thread(() => webDownload(url));
        web.Start();

    }
    // Go (sorting) button
    private void button2_Click(object sender, EventArgs e)
    {

    }
    public void webDownload(string address)
    {
        Thread next = new Thread(() => downloading(address));
        next.Start();
        //  next.Join();

    }
    public void downloading(string address){

        using (WebClient client = new WebClient())
        {
           string content = client.DownloadString(address);
           textBox2.BeginInvoke(new displayDownloadDelegate(displayDownload), content);

        }

   }
    private void displayDownload(string content)
    {
        textBox2.Text = content;
    }

Answer 1

尽管您可以简单地将async-await与异步WebClient.DownloadStringTaskAsync方法一起使用，但是如果您确实必须通过在单独的非UI线程上执行同步WebClient.DownloadString方法(由于某些原因)来使用它，那么您仍然可以非常简单地使用Task.Run()和async-await

private async void button1_Click(object sender, EventArgs e)
{
    textBox1.Enabled = false;
    string url = textBox1.Text;

    using (WebClient client = new WebClient())
    {
        textBox2.Text = await Task.Run(() => client.DownloadString(url));
    }
}