封装WebService的APM为Async、Await模式利于Asp.Net页面调用

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using System.Web;
using System.Web.Services.Protocols;
using System.Web.UI;
using System.Web.UI.WebControls;

namespace WebApplication1
{
    public partial class _Default : Page
    {
        protected async void Page_Load(object sender, EventArgs e)
        {
            //这里不直接用AsyncWebService而用父类SoapHttpClientProtocol的原因是:以后可以针对不同的webservice复用
            SoapHttpClientProtocol soapHttpClient = new global::AsyncWebService("http://localhost:3115/AsyncWebService.asmx");

            //反射创建APM方法异步委托
            var beginFunc = soapHttpClient.GetType()
                .GetMethod("BeginHelloWorld")
                .CreateDelegate(typeof(Func<string, System.AsyncCallback, object, IAsyncResult>), soapHttpClient) as Func<string, System.AsyncCallback, object, IAsyncResult>;
            var endFunc = soapHttpClient.GetType()
                .GetMethod("EndHelloWorld")
                .CreateDelegate(typeof(Func<IAsyncResult, string>), soapHttpClient) as Func<IAsyncResult, string>;

            //打印一下调用异步前线程ID
            StringBuilder sb = new StringBuilder();
            sb.Append("<br />");
            sb.Append("Befort Thread Id:" + Thread.CurrentThread.ManagedThreadId);
            sb.Append("<br />");


            //用TaskFactory封装APM模式为.Net4.5的async await模式
            string result = await Task<string>.Factory.FromAsync<string>(beginFunc,
                endFunc, "zhang san", null);


            //打印一下调用异步后线程ID
            sb.Append("After Thread Id:" + Thread.CurrentThread.ManagedThreadId);
            sb.Append("<br />");

            sb.Append(result);

            ltlResult.Text = sb.ToString();
        }
    }
}