C# ASP 异步存储数据

1.异步委托

在导航栏接收到提交的请求后，调用个各子画面的保存答案方法，之后实例化委托 saveToDB 。

当执行BeginInvoke后，服务器会另起线程执行saveToDB里的的方法，因为这里要保存的数据较多，所以要呈现下一个页面，

也就是：Response.Redirect("~/Default.aspx");调用后，画面虽然迁移了，后台还在执行saveToDB里的方法

 using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Web;
 using System.Web.UI;
 using System.Web.UI.WebControls;
 using System.Threading;
 using System.Threading.Tasks;
 using System.Web.UI.HtmlControls;
 using System.Drawing;

 public partial class SiteMaster : System.Web.UI.MasterPage
 {
     public delegate void ThreadHandler();//异步委托
     BasePage currentPage = null;
     protected void Page_Load(object sender, EventArgs e)
     {
         string strUrl = Request.Url.ToString();

         if (strUrl.Contains("Questionnaire"))//只有在答题页面
         {
             currentPage = Page as BasePage;
         }
     }

     // 导航栏事件
     protected void MenuMaster_MenuItemClick(object sender, MenuEventArgs e)
     {
         string strUrl = Request.Url.ToString();

         Menu menu = (Menu)sender;
         //提交问卷，所有答案入库
         if (menu.SelectedValue == "SubmitAns")
         {
             if (strUrl.Contains("Questionnaire"))//只有在答题页面
             {
                 int position_1 = strUrl.LastIndexOf("Questionnaire") + ;
                 int position_2 = strUrl.LastIndexOf(".");
                 string strCurrentNum = strUrl.Substring(position_1, position_2 - position_1);
                 int num = int.Parse(strCurrentNum);

                 if (checkInput())//输入Check
                 {
                     return;
                 }
                 saveAnswer(num, true, false);

                 AsyncCallback callback = new AsyncCallback(Callback); //回调函数声明
                 ThreadHandler ad = new ThreadHandler(saveToDB);//实例化委托类型
                 IAsyncResult ar = ad.BeginInvoke(callback, ad);//开始调用

             }
             Response.Redirect("~/Default.aspx");
         }
     }

     private bool checkInput()
     {
         return currentPage.checkInput();
     }

     private bool saveAnswer(int num, bool isSubmit, bool isNext)
     {
         if (num ==  && !isSubmit && !isNext)
         {
             currentPage.saveAnswer();
             Page.ClientScript.RegisterStartupScript(this.GetType(), "alert", "<script>alert('已经是第一道题');</script>");
             return false;
         }
         else if (num ==  && !isSubmit && isNext)
         {
             currentPage.saveAnswer();
             Page.ClientScript.RegisterStartupScript(this.GetType(), "alert", "<script>alert('已经是最后一道题');</script>");
             return false;
         }
         else if (num == )
         {
             String className = (String)Request.Form.Get("className");
             String authorName = (String)Request.Form.Get("authorName");
             currentPage.saveAnswer(className, authorName);
         }
         else if (num == )
         {
             String projectName = (String)Request.Form.Get("projectName");
             String DropDownList1 = (String)Request.Form.Get("ctl00$MainContent$DropDownList1");
             String DropDownList2 = (String)Request.Form.Get("ctl00$MainContent$DropDownList2");
             currentPage.saveAnswer(projectName, DropDownList1, DropDownList2);
         }
         else if (num == )
         {
             String Ctime = (String)Request.Form.Get("Ctime");
             String Cname = (String)Request.Form.Get("Cname");
             currentPage.saveAnswer(Ctime, Cname);
         }
         else
         {
             currentPage.saveAnswer();
         }
         return true;
     }

     private void saveToDB()
     {
         UserInfo user = (UserInfo)Session["UserInfo"];
         Answer answer = (Answer)Session["Answer"];
         Dao dao = new Dao();//所有答案入库
         lock (answer)
         {
             //Thread.Sleep(10000);
             if (answer != null)
             {
                 answer.Userid = user.Pkid;
                 if (user.Status == "")
                 {
                     dao.saveAnswer(answer);
                 }
                 else
                 {
                     dao.updateAnswer(answer);
                 }
                 dao.updateUser(user.Pkid.ToString(), "");
                 dao.ConvertToView(answer);
             }
         }
     }

     /// <summary>
     /// 回掉函数
     /// </summary>
     /// <param name="ar"></param>
     void Callback(IAsyncResult ar)
     {
         ThreadHandler andl = (ThreadHandler)ar.AsyncState;
         andl.EndInvoke(ar);
     }
 }