gridview寻找控件方法,该如何处理

gridview寻找控件方法
我在HeaderTemplate中放了一个dropdownlist控件，请问下怎么在除gridview_RowDataBound方法以外的地方获取该控件的对象

[解决办法]
GridView.Rows[i].FindControl("XXX")
[解决办法]
foreach (GridViewRow gr in gridView.Rows)
{
HiddenField hf=gr.FindControl("hf") as HiddenField;
if(hf!=null)
{
//
}
} 

[解决办法]

C# code

dropdownlist ddl = (dropdownlist)e.Row.Cells[3].FindControl("dropdownlist");
[解决办法]
  foreach (GridViewRow r in this.GridView1.Rows)
       {
           DropDownList ddl = r.FindControl("id") as DropDownList ;
       }
[解决办法]
C# code
        DropDownList ddl = this.GridView1.HeaderRow.FindControl("DropDownList1") as DropDownList;