在esri-ajax环境中涮新asp.net显示控件的通用方法
（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
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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);
}
}