private void ClearAllData()
        {
            if (mainMapControl.Map != null && mainMapControl.Map.LayerCount > 0)
            {
                //新建mainMapControl中Map
                IMap dataMap = new MapClass();
                dataMap.Name = "Map";
                mainMapControl.DocumentFilename 
 
= string.Empty;//DocumentFilename為The filename of the last map document loaded into the control
                mainMapControl.Map = dataMap;

                //新建EagleEyeMapControl中Map
                IMap eagleEyeMap = new MapClass();
                eagleEyeMap.Name = "eagleEyeMap";
                EagleEyeMapControl.DocumentFilename 
 
= string.Empty;
                EagleEyeMapControl.Map = eagleEyeMap;
            }
        }