（1）遍历Grid中的所有Item（一行），一次仅展开一行【Single expand in hierarchical grid】

private void RadGrid1_ItemCommand(object source, Telerik.Web.UI.GridCommandEventArgs e)
{
if(e.CommandName == RadGrid.ExpandCollapseCommandName)
  {
foreach(GridItem item in e.Item.OwnerTableView.Items)
   {
if(item.Expanded && item != e.Item)
    {
     item.Expanded = false;
    }
   }
  }
}

http://www.telerik.com/help/aspnet-ajax/grdsingleexpandinhierarchicalgrid.html

（2）展开或者折叠所有行

protected void RadGrid1_ItemCommand(object source, Telerik.WebControls.GridCommandEventArgs e) 

    { 

if (e.CommandName == RadGrid.ExpandCollapseCommandName) 

        { 

            (e.Item.FindControl("btnExpand") as ImageButton).Visible = !(e.Item.FindControl("btnExpand") as ImageButton).Visible; 

            (e.Item.FindControl("btnCollapse") as ImageButton).Visible = !(e.Item.FindControl("btnCollapse") as ImageButton).Visible; 

        } 

if (e.CommandName == "ExpandAll") 

        { 

//Looping through each DataItem and making the "btnExpand" image button in the item visibility  to false and  "btnCollapse" visibility to true 

foreach (GridDataItem GridDataItem in RadGrid1.MasterTableView.GetItems(new GridItemType[] { GridItemType.Item, GridItemType.AlternatingItem })) 

            { 

                ImageButton btnExpand = (ImageButton)GridDataItem.FindControl("btnExpand"); 

                btnExpand.Visible = false; 

                ImageButton btnCollapse = (ImageButton)GridDataItem.FindControl("btnCollapse"); 

                btnCollapse.Visible = true; 

            } 

//Exapanding the DataItem

foreach (GridDataItem item in RadGrid1.Items) 

            { 

                item.Expanded = true; 

            } 

//Hiding the CollapseAll image in the header to true and ExpandAll image in the header to false

            GridHeaderItem GridHeaderItem = e.Item as GridHeaderItem; 

            ImageButton imgCollapseAll = (ImageButton)GridHeaderItem.FindControl("CollapseAll"); 

            imgCollapseAll.Visible = true; 

            ImageButton imgExpandAll = (ImageButton)GridHeaderItem.FindControl("ExpandAll"); 

            imgExpandAll.Visible = false; 

        } 

if (e.CommandName == "CollapseAll") 

        { 

//Looping through each DataItem and making the "btnExpand" image button in the item visibility  to true and  "btnCollapse" visibility to false 

foreach (GridDataItem GridDataItem in RadGrid1.MasterTableView.GetItems(new GridItemType[] { GridItemType.Item, GridItemType.AlternatingItem })) 

            { 

                ImageButton btnExpand = (ImageButton)GridDataItem.FindControl("btnExpand"); 

                btnExpand.Visible = true; 

                ImageButton btnCollapse = (ImageButton)GridDataItem.FindControl("btnCollapse"); 

                btnCollapse.Visible = false; 

            } 

//Collapsing the DataItem

foreach (GridDataItem item in RadGrid1.Items) 

            { 

                item.Expanded = false; 

            } 

//Hiding the CollapseAll image in the header to false and ExpandAll image in the header to true

            GridHeaderItem GridHeaderItem = e.Item as GridHeaderItem; 

            ImageButton imgCollapseAll = (ImageButton)GridHeaderItem.FindControl("CollapseAll"); 

            imgCollapseAll.Visible = false; 

            ImageButton imgExpandAll = (ImageButton)GridHeaderItem.FindControl("ExpandAll"); 

            imgExpandAll.Visible = true; 

        } 

    } 

http://www.telerik.com/community/code-library/aspnet-ajax/grid/custom-expand-collapse-column-with-expandall-collapseall-image-button-in-the-header.aspx

（3）导致Grid重新绑定数据【Commands that invoke Rebind() implicitly】

Here is the complete list of commands that trigger Rebind():

Command Name

Field

ExpandCollapse
RadGrid.ExpandCollapseCommandName

Update
RadGrid.UpdateCommandName

Cancel
RadGrid.CancelCommandName

Delete
RadGrid.DeleteCommandName

Edit
RadGrid.EditCommandName

InitInsert
RadGrid.InitInsertCommandName

PerformInsert
RadGrid.PerformInsertCommandName

RebindGrid
RadGrid.RebindGridCommandName

Page
RadGrid.PageCommandName

Sort
RadGrid.SortCommandName

Filter
RadGrid.FilterCommandName

Note that the following commands do not perform internal rebind:

Select
RadGrid.SelectCommandName

Deselect
RadGrid.DeselectCommandName

http://www.telerik.com/help/aspnet-ajax/grdcommandsthatinvokerebindimplicitly.html