ASP.NET C#生成下拉列表树

效果图:

代码:

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:

            DropDownListHelp ddlHelper = new DropDownListHelp();
            ddlHelper.createDropDownTree(dt, "parentID", "1", "ID","Text", "Text asc", DropDownList1);