在esri-ajax环境中涮新asp.net显示控件的通用方法

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原来一直在esri的server论坛潜水，刚到esri-china server 论坛来学习，发现有不少人被esri-ajax困惑。我以前也被这个问题搞得晕头转向，现在基本明白原理了。
（1）arcgis server 9.2 开始为解决有map页面的局部刷新问题，在asp net 2.0 callback机制的基础上扩充引入了esri-ajax机制，基本上所有与map 有关的控件如map,toc,taskresult等均引入了esri-ajax，这样在有这些esri-ajax机制的esri控件的页面中，原asp.net显示控件涮新方法不能再使用原服务器端的refresh，应由client与server端的互动才行。
（2）mircosoft为解决asp net 2.0 callback机制的难用问题，后推出了ms ajax extention 1.0,使得asp net上的ajax实现大为简单，可惜arcgis server 9.2是在ms ajax extention 1.0（http://asp.net/ajax/downloads/default.aspx）推出前的产品，不支持它，arcgis server 9.3会支持ms ajax extention技术，目前要实现有esri控件与原aspnet 2.0控件页面的全部局部涮新，需同时使用ms ajax与esri asjx,它们的共存是没有问题的（Using ASP.NET AJAX with the Web ADF，见 http://blogs.esri.com/Dev/blogs/ ... th-the-Web-ADF.aspx），我已在一个完整的web gis环境中使用过了，效果与稳定性均令人满意。

（3）如何在esri-ajax环境中涮新asp.net显示控件呢，使用下面的通用方法：
private CallbackResult RefreshControlHtml(Control control)
{

      System.IO.StringWriter sw = new System.IO.StringWriter();

      HtmlTextWriter writer = new HtmlTextWriter(sw);

      control.RenderControl(writer);

      string htmlContent = sw.ToString();

      sw.Close();

      return new CallbackResult(control, "content", htmlContent);

}

在gridview,listbox,label等asp.net显示控件需涮新时，调用：

map1.CallbackResults.Add(RefreshControlHtml(mygridview1));
或 map1.CallbackResults.Add(RefreshControlHtml(mylistbox1));等
-------------------------------------------------------------------------------------------------------------------------------
为示范起见，我贴部分代码。

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using ESRI.ArcGIS.ADF.Web.UI.WebControls;
using ESRI.ArcGIS.ADF.Web.UI.WebControls.Tools;
using ESRI.ArcGIS.ADF.Web;
using ESRI.ArcGIS.ADF;
using System.Collections;
using ESRI.ArcGIS.ADF.Web.Display.Graphics;
using ESRI.ArcGIS.ADF.Web.DataSources.ArcGISServer;
using ESRI.ArcGIS.ADF.ArcGISServer;

/// <summary>
/// Command_wsh3 的摘要说明
/// </summary>

public class Command_wsh3 : IMapServerCommandAction
{
   public void ServerAction(ToolbarItemInfo info)
{
      Map mapctrl = (Map)info.BuddyControls[0];

      // 0. 找到查询条件定义控件
      FloatingPanel myfloatingpanel = (FloatingPanel) mapctrl.Page.FindControl("FloatingPanel1");
      DropDownList mydroplist1 = (DropDownList)myfloatingpanel.FindControl("DropDownList1");
      int myDropindexVlaue = mydroplist1.SelectedIndex;

      string jsfunction = string.Format("alert('My Result:{0}');", myDropindexVlaue.ToString());
      CallbackResult showcr = new CallbackResult(null, null, "javascript", jsfunction);
      mapctrl.CallbackResults.Add(showcr);



      // 1.用query方法得到datatable

      System.Data.DataTable qdatatable=new DataTable();

      IEnumerable func_enum = mapctrl.GetFunctionalities();
      foreach (ESRI.ArcGIS.ADF.Web.DataSources.IGISFunctionality gisfunctionality in func_enum)
      {
         ESRI.ArcGIS.ADF.Web.DataSources.IGISResource gisresource = gisfunctionality.Resource;
         bool supported = gisresource.SupportsFunctionality(typeof(ESRI.ArcGIS.ADF.Web.DataSources.IQueryFunctionality));

         if (supported)
         {
            ESRI.ArcGIS.ADF.Web.DataSources.IQueryFunctionality qfunc;
            qfunc = (ESRI.ArcGIS.ADF.Web.DataSources.IQueryFunctionality)gisresource.CreateFunctionality(typeof(ESRI.ArcGIS.ADF.Web.DataSources.IQueryFunctionality), null);

            string[] lids;
            string[] lnames;
            qfunc.GetQueryableLayers(null, out lids, out lnames);

            ESRI.ArcGIS.ADF.Web.Geometry.Envelope env = new ESRI.ArcGIS.ADF.Web.Geometry.Envelope(-100, -100, 100, 100);
            env = mapctrl.Extent;

            ESRI.ArcGIS.ADF.Web.SpatialFilter spatialfilter = new ESRI.ArcGIS.ADF.Web.SpatialFilter();
            spatialfilter.Geometry = env;
            spatialfilter.ReturnADFGeometries = true;
            spatialfilter.MaxRecords = 1000;

            for (int i = 0; i < lids.Length; i++)

               {
               // if (i == 1)  // 主要机构
                  if ( i== 1 )
                  {
                       qdatatable = qfunc.Query(null, lids, spatialfilter);
                     // qdatatable.TableName = gisresource.Name + "_" + lnames;
                     qdatatable.TableName = lnames + " (当前区域: " + qdatatable.Rows.Count.ToString() + ")";

                  }
            }
         }
      }
      // 2  在datatable中加入一个LINK字段指示详情

      // 3 把 datatable Converter To GraphicsLayer
   // 4  把GraphicsLayer中的IsSelectedColumn字段set true


      // 5 把 graphicsLayer 加载到 mapresource

      //  6 refresh map

      if (mapctrl.ImageBlendingMode == ImageBlendingMode.WebTier)
      {
         mapctrl.Refresh();
      }
      else
         if (mapctrl.ImageBlendingMode == ImageBlendingMode.Browser)
         {
            mapctrl.RefreshResource(gResource.Name);

         }


      // 7- 把dataset放入 taskresult

      // 8- 刷新taskresult

      myTaskResults.Refresh();
      foreach (CallbackResult cr in myTaskResults.CallbackResults)
      {
         mapctrl.CallbackResults.Add(cr);
      }

      // 9 - 用 gridview 显示 graphicsLayer

      GridView mygridview1 = (GridView)mapctrl.Page.FindControl("GridView1");
      mygridview1.DataSource = graphicsLayer;
      mygridview1.DataBind();

      mapctrl.CallbackResults.Add(RefreshControlHtml(mygridview1));

      TextBox mytextbox = (TextBox)mapctrl.Page.FindControl("TextBox1");

      mytextbox.Text = "当前区域:" + qdatatable.Rows.Count.ToString();
      mapctrl.CallbackResults.Add(RefreshControlHtml(mytextbox));

}
private CallbackResult RefreshControlHtml(Control control)
{

      System.IO.StringWriter sw = new System.IO.StringWriter();

      HtmlTextWriter writer = new HtmlTextWriter(sw);

      control.RenderControl(writer);

      string htmlContent = sw.ToString();

      sw.Close();

      return new CallbackResult(control, "content", htmlContent);

}

}