多线程：子线程执行过程中调用主线程

直接在子线程中调用方法，线程的ID为3，通过Post则为1

执行结果：

2018-09-13 11:21:11:1735 : 主线程：1

2018-09-13 11:21:16:0583 : 子线程：3

2018-09-13 11:21:16:0739 : ShowForm：1发送失败！

2018-09-13 11:21:16:1051 : ShowForm：3发送失败！

 public class TestClass
    {

        private SynchronizationContext mainThreadSynContext;
        public void SendTestResult(string Url, string TestResult)
        {
            mainThreadSynContext = SynchronizationContext.Current; 
            Thread t = new Thread(p => Start(Url, TestResult));
            t.Start();
            LogWriteUtility.Instance.LogWrite("主线程："+Thread.CurrentThread.ManagedThreadId.ToString());
        }

       
        private void Start(string url, string testResult)
        {
            try
            {
                Thread.Sleep(TimeSpan.FromSeconds(5));
                LogWriteUtility.Instance.LogWrite("子线程：" + Thread.CurrentThread.ManagedThreadId.ToString());
                throw new Exception("发送失败！");
            }
            catch (Exception ex)
            {
                //SendOrPostCallback myDelegate;
                //myDelegate = new SendOrPostCallback(ShowForm);
                mainThreadSynContext.Post(ShowForm, ex);
                this.ShowForm(ex);
            }
        }

        private void ShowForm(object state)
        {
            Exception ex = state as Exception;
            LogWriteUtility.Instance.LogWrite("ShowForm：" + Thread.CurrentThread.ManagedThreadId.ToString()+ex.Message);
            //ErrorForm form = new ErrorForm();
            //form.ShowDialog();
        }
    }