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/// <summary>
/// 一个通用的树状菜单类
/// </summary>
public class Tree
{
private string _treeHtml;
private DataTable _dataTable;
/// <summary>
/// 根据DataTable对象,生成一棵树
/// </summary>
/// <param name="dataTable">树中节点的数据</param>
/// <returns>树的HTML代码</returns>
public string CreateTree(DataTable dataTable)
{
this._dataTable = dataTable;
this.CreateSubTree(0);
return _treeHtml;
}
/// <summary>
/// 获取父节点编号为parentId的所有节点,并用DataTable返回
/// </summary>
/// <param name="parentId">父节点编号</param>
/// <returns>DataTable形式的所有孩子节点数据</returns>
private DataTable GetChilds(int parentId)
{
DataTable childNodes = new DataTable();
childNodes = this._dataTable.Clone();
foreach (DataRow dr in this._dataTable.Rows)
{
if (Convert.ToInt32(dr["ParentId"]) == parentId)
{
childNodes.ImportRow(dr);
}
}
return childNodes;
}
/// <summary>
/// 判断编号为nodeId的节点是否为叶子节点
/// </summary>
/// <param name="nodeId">待判断的节点编号</param>
/// <returns>是叶子节点:返回true;否则:返回false</returns>
private bool IsLeaf(int nodeId)
{
foreach (DataRow dr in this._dataTable.Rows)
if (Convert.ToInt32(dr["ParentId"]) == nodeId)
return false;
return true;
}
/// <summary>
/// 得到编号为nodeId的节点的父节点编号
/// </summary>
/// <param name="nodeId">节点编号</param>
/// <returns>父节点编号</returns>
private int GetParent(int nodeId)
{
foreach (DataRow dr in this._dataTable.Rows)
if (Convert.ToInt32(dr["NodeId"]) == nodeId)
return Convert.ToInt32(dr["ParentId"]);
return -1;
}
/// <summary>
/// 得到编号为nodeId的节点的级别,根节点为0
/// </summary>
/// <param name="nodeId">待计算的巨额电编号</param>
/// <returns>节点的级别,根节点为0</returns>
private int GetLevel(int nodeId)
{
int parentId = GetParent(nodeId);
if (parentId == 0) return 1;
else
return GetLevel(parentId) + 1; //递归
}
/// <summary>
/// 递归生成根编号为nodeId的树
/// </summary>
/// <param name="nodeId">所要生成子树的根节点</param>
private void CreateSubTree(int nodeId)
{
DataTable childNodes = this.GetChilds(nodeId); //获取根节点的所有孩子
//循环生成根节点的所有孩子对应的HTML
int childId = 0;
foreach (DataRow dr in childNodes.Rows)
{
childId = Convert.ToInt32(dr["nodeId"]);
this._treeHtml += "<div id=div_" + childId.ToString() + ">";
//根据该孩子的级别,生成一些空格,以体现层次结构
for (int i = 0; i < GetLevel(childId); i++)
this._treeHtml += " ";
//如果该孩子是叶子节点,则生成其HTML代码
if (this.IsLeaf(childId))
{
this._treeHtml += "<img src='..\\Images\\folder.gif'/><a href=" + dr["Url"] + ">" + dr["Text"] + "</a></div>";
}
//如果该孩子为中间节点,则首先构造其HTML,然后递归生成其所有孩子的HTML
else
{
this._treeHtml += "<img src='..\\Images\\folderopen.gif'/><a href=" + dr["Url"] + ">" + dr["Text"] + "</a></div>";
this.CreateSubTree(childId);//递归
}
}
}
}