MOSS & WSS 中编写异步回调的WebPart

     越来越多的应用迁移到MOSS上，作为其基本应用元件的WebPart自然得到最大最多的关注了，因此如何编写高性能高的WebPart 也越来越急迫了，利用asp.net2.0基本的回调功能支持，可以在WebPart中实现多线程的效果哦。

     我们在SPS2003的时候使用：Microsoft.SharePoint.WebPartPages.WebPart.RegisterWorkItem    

　　MOSS 2007 自然升级到：Page.RegisterAsyncTask

关于　Page.RegisterAsyncTask可以参考ＭＳＤＮ：http://msdn.microsoft.com/en-us/library/system.web.ui.page.registerasynctask.aspx　介绍，下面来看看基本的实现代码：

定义了３个类：

• WebPartMultiThread class
• WebPartMultiThread definition class
• WebPartMultiThread package class

 WebPartMultiThread　class:

using System;
using System.Web;
using System.Web.UI;
using System.Threading;
using System.Xml.Serialization;
using Microsoft.SharePoint;
using Microsoft.SharePoint.WebPartPages;

public class WorkItemSample : 
       Microsoft.SharePoint.WebPartPages.WebPart
{
    string log = "";
    ManualResetEvent mre = new ManualResetEvent(false);

    bool threadTimeOut = false;
    WebPartMultiThread MultiThread;

    public WorkItemSample()
    {
    }
    protected override void OnPreRender(EventArgs e)
    {
        log += "before register: " + 
               DateTime.Now.ToLongTimeString() + "<BR>";
        MultiThread = new WebPartMultiThread(threadTimeOut, this.Page);
        MultiThread.RegisterWorkItemCallback(new WaitCallback(DoWork), null);
        //DoWork(null);
        log += "after register: " + 
               DateTime.Now.ToLongTimeString() + "<BR>";
    }
    protected override void RenderWebPart(HtmlTextWriter output)
    {
        if (MultiThread != null && MultiThread.ThreadTimeOut)
        {
            string TimeoutMessage = "Timed out";
            MultiThread.RenderWorkItemTimeout(output, TimeoutMessage);                
        }
        else
        {
            log += "RenderWebPart: " + 
                   DateTime.Now.ToLongTimeString() + "<BR>";
            output.Write(log);
        }           
    }

    // Sleep for 5 seconds to simulate doing work
    private void DoWork(object o)
    {
        log += "before DoWork: " + DateTime.Now.ToLongTimeString() + 
               this.Title + "<BR>";
        Thread.Sleep(7000);
        log += "After DoWork: " + DateTime.Now.ToLongTimeString() + 
               this.Title + "<BR>";
        mre.Set();
    }
}

 

　The WebPartMultiThread definition class：

using System;
using System.Web;
using System.Web.UI;
using System.Threading;
using System.Xml.Serialization;
public class WebPartMultiThread
{
    private bool _threadtimeout;
    private Page _page;

    public bool ThreadTimeOut
    {
        set
        {
            _threadtimeout = value;
        }
        get
        {
            return _threadtimeout;
        }
    }

    public System.Web.UI.Page myPage
    {
        set
        {
            _page = value;
        }
        get
        {
            return _page;
        }
    }
    public WebPartMultiThread(bool pThreadTimeOut, Page pPage)
    {
        ThreadTimeOut = pThreadTimeOut;
        myPage = pPage;
    }

    public bool RegisterWorkItemCallback(WaitCallback beginCallBack, object state)
    {
        if (!this.ThreadTimeOut)
        {
            WebPartMultiThreadPacket pa = new WebPartMultiThreadPacket();
            pa.state = state;
            pa.beginCallBack = beginCallBack;
            PageAsyncTask task = new PageAsyncTask(new BeginEventHandler(
                                 this.OnTaskBeginWithWaitCallback), 
                                 new EndEventHandler(this.OnTaskEnd), 
                                 new EndEventHandler(this.OnTaskTimeout), pa, true);

            if (this.myPage != null)
            {
                this.myPage.RegisterAsyncTask(task);
            }
        }
        else
            return false;
        return true;
    }
    private IAsyncResult OnTaskBeginWithWaitCallback(object sender, 
                         EventArgs e, AsyncCallback cb, object o)
    {
        return ((WebPartMultiThreadPacket)o).beginCallBack.BeginInvoke(
                ((WebPartMultiThreadPacket)o).state, cb, null);
    }
    private void OnTaskEnd(IAsyncResult ar)
    {
    }
    private void OnTaskTimeout(IAsyncResult ar)
    {
        this.ThreadTimeOut = true;
    }
    public void RenderWorkItemTimeout(HtmlTextWriter output, string outputMessage)
    {
        output.Write(outputMessage);
    }
}

The WebPartMultiThread package class：

using System;
using System.Collections.Generic;
using System.Text;
using System.Threading;
using System.Xml.Serialization;
public class WebPartMultiThreadPacket
{
    public WaitCallback beginCallBack;
    public object state;

    public WebPartMultiThreadPacket()
    {
    }
}

我们通过模拟耗时操作：Thread.Sleep(7000);来达到异步多处理请求效果，自然得到相当好的用户体验。

  此处下载示例代码