异步Web Part

代码如下：

using System;
using System.Runtime.InteropServices;
using System.Web.UI;


namespace WebPartCollection
{
    [Guid("d2b37a6c-650c-4ef4-962c-85297f15b0b5")]
    public class AsyWebServiceWebPart : System.Web.UI.WebControls.WebParts.WebPart, ICallbackEventHandler
    {
        public AsyWebServiceWebPart()
        {
        }

        protected override void CreateChildControls()
        {
            base.CreateChildControls();
        }
        protected override void OnInit(EventArgs e)
        {
                
            base.OnInit(e);
            if (Page.IsPostBack)
            {
                return;
            }
            string serverCallJs = Page.ClientScript.GetCallbackEventReference(this, "",
                "AsyWebServiceWebPart_Callback", "", "AsyWebServiceWebPart_Callback", true);

            string clientCallbackJs = "function AsyWebServiceWebPart_Callback(returnValue,context)"+
                "{document.getElementById('"+this.ClientID+"_content').innerHTML=returnValue;}\n";

            Page.ClientScript.RegisterStartupScript(this.GetType(), "loadWether", clientCallbackJs + serverCallJs + ";\n", true);
        }
        protected override void Render(HtmlTextWriter writer)
        {
            writer.Write("<div id='" + this.ClientID + "_content' style='text-align:center'>loading…</div>");
        }


        #region ICallbackEventHandler 成员

         string GetCallbackResult()
        {
            WebXML.WeatherWebService weathreWS = new CodeArt.SharePoint.WebXML.WeatherWebService();
            string[] data = weathreWS.getWeatherbyCityName("上海");
            return data[5] + "<br/>" + data[6] + "<br/>" + data[7];
        }

         void RaiseCallbackEvent(string eventArgument)
        {

        }

        #endregion
    }
}