ThreadPool.QueueUserWorkItem 方法 (WaitCallback)

说明：将方法排入队列以便执行，WaitCallback，表示要执行的方法。如果将方法成功排入队列，则为 true；否则为 false。

示例：addtest方法需要比较长的时间来响应，因此在button1_Click被点击以后，程序会失去响应，使用ThreadPool.QueueUserWorkItem 后，页面会继续响应其他时间，等addtest执行结束后，响应结果。

<Window x:Class="WpfAppThread.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="Window1" Height="300" Width="300">
    <Grid>
        <Button Height="23" HorizontalAlignment="Left" Margin="9,23,0,0" Name="button1" VerticalAlignment="Top" Width="75" Click="button1_Click">ButtonOne</Button>
        <Button Height="23" Margin="102,23,101,0" Name="button2" VerticalAlignment="Top" Click="button2_Click">ButtonTwo</Button>
    </Grid>
</Window>

        private void button1_Click(object sender, RoutedEventArgs e)
        {
            ThreadPool.QueueUserWorkItem(new WaitCallback(addtest),"Testaa"); 
            //addtest();
        }

        private void addtest(object aa)
        {
            long result=0;
            for (int i = 0; i < 1000000000; i++)
            {
                result += i;
            }
            MessageBox.Show(result.ToString()+aa.ToString());
            
        }

        private void button2_Click(object sender, RoutedEventArgs e)
        {
            MessageBox.Show("two");
        }