由于书本内容较少，自己知识储备量不足，在c#客户端请求http登陆的时候，因为占用ui线程，直接造成卡死（假死），百度谷歌了一堆，还是一脸懵逼，通过在loc论坛询问后，得知用Task.Run可以解决此问题，于是又出来折腾，发现不行，还是因为自己菜啊！

界面：修改按钮点击类为async

private async void button2_Click(object sender, EventArgs e)
{
    string user = textBox3.Text;
    string pass = textBox4.Text;
    string postdata = "user=" + user + "&pass=" + pass;
    var result = await AsyncLogin(postdata);
    MessageBox.Show(result);
}

请求函数，sendpost函数是处理访问并返回值，代码

private Task<string> AsyncRegister(string postdata)
{
    var result = Task.Run(() =>
    {
        return sendPost(postdata, "http://localhost/admin/login");
    });
    return result;
}
//请求函数
public string sendPost(string postData, string requestUrlString)
{
    UTF8Encoding encoding = new UTF8Encoding();
    byte[] data = encoding.GetBytes(postData);
    HttpWebRequest myRequest = (HttpWebRequest)WebRequest.Create(requestUrlString);
    myRequest.Method = "POST";
    myRequest.ContentType = "application/x-www-form-urlencoded";
    myRequest.Timeout = 30000;
    Stream newStream = myRequest.GetRequestStream();
    newStream.Write(data, 0, data.Length);
    newStream.Close();
    HttpWebResponse myResponse = (HttpWebResponse)myRequest.GetResponse();
    StreamReader reader = new StreamReader(myResponse.GetResponseStream(), Encoding.UTF8);
    return reader.ReadToEnd();
}