如果 DataGrid 中的行还未被加载，即 LoadingRow 事件未发生，那么针对此行的 GetCellContent() 是不可能得到东西的，只能为 null。

 下面两种语法，只是变相的形式而已。

 　　　for (int i = 0; i < dgETL.Items.Count; i++)

            {

                CheckBox selectCheckBoxInCell = dgETL.Columns[0].GetCellContent(dgETL.Items[i]) as CheckBox;

                if (selectCheckBoxInCell != null)

                {

                    selectCheckBoxInCell.IsChecked = cbxOne.IsChecked;

                }

            }

            foreach (var item in dgETL.Items)

            {

                CheckBox selectCheckBoxInCell = dgETL.Columns[0].GetCellContent(item) as CheckBox;

                if (selectCheckBoxInCell != null)

                {

                    selectCheckBoxInCell.IsChecked = cbxOne.IsChecked;

                }

            }

 GridViewRow s = ((GridViewRow)PSFileDataGrid.ItemContainerGenerator.ContainerFromIndex(1));

            if (s != null)

            {

                Button sb = null;

                GridViewCellBase j =

                      (from c in s.Cells where c.Column.Name == "uid" select c).FirstOrDefault();

                if (j != null)

                {

                    sb = j.Template.FindName("button1", j) as Button;

                    sb.IsEnabled = false;

                }

            }