效果图:

代码:
复制代码 代码如下:
using System.Data;
using System.Web.UI.WebControls;
/// <summary>
/// 根据DataTable生成下拉列表树
/// </summary>
public class DropDownListHelp
{
private string gridline;
private DataTable dt;
public DropDownListHelp()
{
//
//TODO: 在此处添加构造函数逻辑
//
}
/// <summary>
/// 根据Datatable生成树形下拉菜单
/// </summary>
/// <param name="datatable"></param>
/// <param name="parentKeyField">上级节点关键字段</param>
/// <param name="parentKey">上级节点值</param>
/// <param name="keyField">本节点关键字段</param>
/// <param name="sortString">排序字符串</param>
/// <param name="ddl">DownList</param>
public void createDropDownTree(DataTable datatable, string parentKeyField, string parentKey, string keyField, string textField, string sortString, DropDownList ddl)
{
dt = datatable;
ddl.Items.Add(new ListItem("", ""));
addChildItems(parentKeyField, parentKey, keyField, textField, sortString, ddl);
}
/// <summary>
/// 递归生成树节点
/// </summary>
/// <param name="parentKeyField">上级节点关键字段</param>
/// <param name="parentKey">上级节点值</param>
/// <param name="keyField">本节点关键字段</param>
/// <param name="sortString">排序字符串</param>
/// <param name="ddl">DownList控件</param>
/// <returns></returns>
private void addChildItems(string parentKeyField, string parentKey, string keyField, string textField, string sortString, DropDownList ddl)
{
DataView dv = new DataView(dt, parentKeyField + "='" + parentKey + "'", sortString, DataViewRowState.CurrentRows);
int a = dv.Count;
if (dv.Count == 0)
{
return;
}
for (int i = 0; i < a; i++)
{
gridline = "";
dv.RowFilter = parentKeyField + "='" + parentKey + "'";
dv.Sort = sortString;
getTreeLine(parentKeyField, dv[i][parentKeyField].ToString(), keyField, dv[i][keyField].ToString(), sortString);
dv.RowFilter = parentKeyField + "='" + parentKey + "'";
dv.Sort = sortString;
ddl.Items.Add(new ListItem(gridline + (i == a - 1 ? "┗" : "┣") + dv[i][textField].ToString(), dv[i][keyField].ToString()));
addChildItems(parentKeyField, dv[i][keyField].ToString(), keyField, textField, sortString, ddl);
}
dv.Dispose();
}
/// <summary>
/// 回溯生成树的连接线
/// </summary>
/// <param name="parentKeyField">上级节点关键字段</param>
/// <param name="parentKey">上级节点值</param>
/// <param name="keyField">本节点关键字段</param>
/// <param name="nodeKey">本节点值</param>
/// <param name="sortString">排序字符串</param>
/// <returns></returns>
private void getTreeLine(string parentKeyField, string parentKey, string keyField, string nodeKey, string sortString)
{
//选择父层节点
DataView dv = new DataView(dt, keyField + "='" + parentKey + "'", sortString, DataViewRowState.CurrentRows);
if (dv.Count > 0)
{
//选择父节点同级节点
dv.RowFilter = parentKeyField + "='" + dv[0][parentKeyField].ToString() + "'";
dv.Sort = sortString;
for (int j = 0; j < dv.Count; j++)
{
if (dv[j][keyField].ToString() == parentKey)
{
if (j == dv.Count - 1)
{
gridline = "　" + gridline;
}
else
{
gridline = "┃" + gridline;
}
}
}
getTreeLine(parentKeyField, dv[0][parentKeyField].ToString(), keyField, dv[0][keyField].ToString(), sortString);
}
dv.Dispose();
}
}

调用:
复制代码 代码如下:
DropDownListHelp ddlHelper = new DropDownListHelp();
ddlHelper.createDropDownTree(dt, "parentID", "1", "ID","Text", "Text asc", DropDownList1);