public void Init()
        {
            AsyncComputeCaller caller   = new AsyncComputeCaller(this.Cal_num);
            AsyncCallback      callback = new AsyncCallback(ComputerCallback);

            //BeginInvoke不会阻塞,实现异步调用 执行传入的ComputerCallback的回调方法
            caller.BeginInvoke(num1, num2, callback, caller);
        }
        /// <summary>
        /// 执行后续处理,可以在UI线程中直接更新界面不会有阻塞,假死
        /// </summary>
        /// <param name="result"></param>
        private void ComputerCallback(IAsyncResult result)
        {
            AsyncComputeCaller caller = (AsyncComputeCaller)result.AsyncState;

            caller.EndInvoke(result);
        }