C#递归实现Treeview

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无意发现在网上很刚学C#的朋友们都在找关于C#如何递归实现TreeView的绑定，见网上很多例子都比较深奥，我特意写了个比较简单易懂的例子帮助大家了解C#TreeView的操作与递归的实现...

本文只是用递归的方式简单实现TreeView的操作，可能存在性能上的问题，仅供初学者参考。

效果图：

一：创建数据库和数据表（Area）

二：创建AreaManage项目：

项目结构：

以下是各个类文件的代码：

1.SQLOperate.cs

/// <summary>///SQLOperate 的摘要说明/// </summary>public class SQLOperate{ /// <summary> /// 根据parentId查地区信息 /// </summary> /// <param name="parentId"></param> /// <returns></returns> public static DataTable GetAreaInfoByParentId(int parentId) { string sql = "select * from Area where ParentId = @ParentId"; SqlParameter[] para = new SqlParameter[] { new SqlParameter("@ParentId",parentId) }; return DBHelper.GetDataSet(sql, para); } /// <summary> /// 根据ID查找地区 /// </summary> /// <param name="areaId"></param> /// <returns></returns> public static DataTable GetAreaInfoById(int areaId) { string sql = "select * from Area where AreaId = @AreaId"; SqlParameter[] para = new SqlParameter[] { new SqlParameter("@Areaid",areaId)}; return DBHelper.GetDataSet(sql, para); } /// <summary> /// 增加同一级地区 /// </summary> /// <param name="parentId"></param> /// <param name="areaName"></param> /// <returns></returns> public static int AddParityClass( int parentId,string areaName) { string sql = "insert into Area(AreaName,ParentId)values(@AreaName,@ParentId)"; SqlParameter[] para = new SqlParameter[] { new SqlParameter("@AreaName",areaName), new SqlParameter("@ParentId",parentId) }; return DBHelper.ExecuteCommand(sql, para); } /// <summary> /// 增加下一级地区 /// </summary> /// <param name="parentId"></param> /// <param name="areaName"></param> /// <returns></returns> public static int AddNextClass(int parentId, string areaName) { string sql = "insert into Area(AreaName,ParentId)values(@AreaName,@ParentId)"; SqlParameter[] para = new SqlParameter[] { new SqlParameter("@AreaName",areaName), new SqlParameter("@ParentId",parentId) }; return DBHelper.ExecuteCommand(sql, para); } /// <summary> /// 查询是否有子集 /// </summary> /// <param name="parentId"></param> /// <returns></returns> public static bool CheckNextClass(int parentId) { string sql = "select AreaId from Area where ParentId = @ParentId"; SqlParameter[] para = new SqlParameter[] { new SqlParameter("@ParentId",parentId)}; using(SqlDataReader reader = DBHelper.ExecuteReader(sql,para)) { if (reader.Read()) return true; else return false; } } /// <summary> /// 删除地区 /// </summary> /// <param name="areaId"></param> /// <returns></returns> public static int DeleteClass(int areaId) { string sql = "Delete from Area where AreaId = @AreaId"; SqlParameter[] para = new SqlParameter[] { new SqlParameter("AreaId",areaId)}; return DBHelper.ExecuteCommand(sql, para); } /// <summary> /// 修改地区名 /// </summary> /// <param name="areaId"></param> /// <param name="areaName"></param> /// <returns></returns> public static int ModifyClass(int areaId ,string areaName) { string sql = "Update Area set AreaName = @AreaName where AreaId = @AreaId"; SqlParameter[] para = new SqlParameter[] { new SqlParameter("@AreaName", areaName), new SqlParameter("@AreaId",areaId) }; return DBHelper.ExecuteCommand(sql, para); }}

2.DBHelper

/// <summary>///DBHelper 的摘要说明/// </summary>public static class DBHelper{ private static SqlConnection connection; public static SqlConnection Connection { get { //读配置文件 // string connectionString = ConfigurationManager.ConnectionStrings["数据库名"].ConnectionString.ToString(); string connectionString = "server=服务器;database=数据库名;uid=sa;pwd=sa"; if (connection == null) { connection = new SqlConnection(connectionString); connection.Open(); } else if (connection.State == System.Data.ConnectionState.Closed) { connection.Open(); } else if (connection.State == System.Data.ConnectionState.Broken) { connection.Close(); connection.Open(); } return connection; } } public static int ExecuteCommand(string safeSql) { SqlCommand cmd = new SqlCommand(safeSql, Connection); int result = cmd.ExecuteNonQuery(); return result; } public static int ExecuteCommand(string sql, SqlParameter[] values) { SqlCommand cmd = new SqlCommand(sql, Connection); cmd.Parameters.AddRange(values); return cmd.ExecuteNonQuery(); } public static int ExecuteCommand(string sql, SqlParameter value) { SqlCommand cmd = new SqlCommand(sql, Connection); cmd.Parameters.Add(value); int result = cmd.ExecuteNonQuery(); return result; } public static int ExecuteScalar(string safeSql) { SqlCommand cmd = new SqlCommand(safeSql, Connection); int result = (int)cmd.ExecuteScalar(); return result; } public static int ExecuteScalar(string sql, SqlParameter[] values) { SqlCommand cmd = new SqlCommand(sql, Connection); cmd.Parameters.AddRange(values); int result = (int)cmd.ExecuteScalar(); return result; } public static int ExecuteScalar(string sql, SqlParameter value) { int result = 0; SqlCommand cmd = new SqlCommand(sql, Connection); cmd.Parameters.Add(value); try { result = (int)cmd.ExecuteScalar(); } catch (Exception ex) { result = 0; } return result; } public static SqlDataReader ExecuteReader(string safeSql) { SqlCommand cmd = new SqlCommand(safeSql, Connection); SqlDataReader reader = cmd.ExecuteReader(); return reader; } public static SqlDataReader ExecuteReader(string sql, SqlParameter value) { SqlCommand cmd = new SqlCommand(sql, Connection); cmd.Parameters.Add(value); SqlDataReader reader = cmd.ExecuteReader(); return reader; } public static SqlDataReader ExecuteReader(string sql, SqlParameter[] values) { SqlCommand cmd = new SqlCommand(sql, Connection); cmd.Parameters.AddRange(values); SqlDataReader reader = cmd.ExecuteReader(); return reader; } public static DataTable GetDataSet(string safeSql) { DataSet ds = new DataSet(); SqlCommand cmd = new SqlCommand(safeSql, Connection); SqlDataAdapter da = new SqlDataAdapter(cmd); da.Fill(ds); return ds.Tables[0]; } public static DataTable GetDataSet(string sql, params SqlParameter[] values) { DataSet ds = new DataSet(); SqlCommand cmd = new SqlCommand(sql, Connection); cmd.Parameters.AddRange(values); SqlDataAdapter da = new SqlDataAdapter(cmd); da.Fill(ds); return ds.Tables[0]; } public static SqlDataReader GetReader(string safeSql) { SqlCommand cmd = new SqlCommand(safeSql, Connection); SqlDataReader reader = cmd.ExecuteReader(); return reader; } public static SqlDataReader GetReader(string sql, params SqlParameter[] values) { SqlCommand cmd = new SqlCommand(sql, Connection); cmd.Parameters.AddRange(values); SqlDataReader reader = cmd.ExecuteReader(); return reader; }}

3.模板页（MasterPage.master）：

<%@ Master Language="C#" AutoEventWireup="true" CodeFile="MasterPage.master.cs" Inherits="MasterPage" %><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head runat="server"> <title>地区管理</title></head><body> <form id="form1" runat="server"> <div> <div style="float:left; width:300px" > <asp:TreeView ID="tvArea" runat="server"> </asp:TreeView> </div> <div style="float:left" mce_style="float:left"> <asp:ContentPlaceHolder ID="cphArea" runat="server"> </asp:ContentPlaceHolder> </div> </div> </form></body></html>

4.模板页后台代码：（MasterPage.master.cs）:

5. Default.aspx 页面代码（只为显示效果，不曾考虑排版）:

<%@ Page Title="" Language="C#" MasterPageFile="~/MasterPage.master" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %><asp:Content ID="Content1" ContentPlaceHolderID="cphArea" Runat="Server"> <mce:script language="javascript" type="text/javascript"></mce:script> <table border="1"> <tr> <td> ID:</td> <td> <asp:Label ID="lblAreaId" runat="server"></asp:Label> </td> </tr> <tr> <td> AreaName:</td> <td> <asp:Label ID="lblAreaName" runat="server"></asp:Label></td> </tr> <tr> <td> ParentId:</td> <td> <asp:Label ID="lblParentId" runat="server"></asp:Label></td> </tr> <tr> <td colspan="2"> 请输入地区名... </td> </tr> <tr> <td> 地区名：</td> <td> <asp:TextBox ID="txtAreaName" runat="server"></asp:TextBox></td> </tr> <tr> <td colspan="2" style="height: 22px"> <asp:Button ID="btnDel" runat="server" Text=" 删除 " onclick="btnDel_Click" /> <asp:Button ID="btnModify" runat="server" Text=" 修改 " OnClientClick="return checkAreaName()" onclick="btnModify_Click" /> <asp:Button ID="btnAddParityClass" runat="server" Text=" 添加同级 " OnClientClick="return checkAreaName()" onclick="btnAddParityClass_Click" /> <asp:Button ID="btnAddNextClass" runat="server" Text=" 添加下一级 " OnClientClick="return checkAreaName()" onclick="btnAddNextClass_Click" /> </td> </tr> </table> </asp:Content>

6.Default.aspx.cs(后台代码):

using System;using System.Collections.Generic;using System.Linq;using System.Web;using System.Web.UI;using System.Web.UI.WebControls;using System.Data;public partial class _Default : System.Web.UI.Page{ protected void Page_Load(object sender, EventArgs e) { if (!IsPostBack) { Bind(); } } /// <summary> /// 初始化数据 /// </summary> private void Bind() { int id = Convert.ToInt32(Request.QueryString["id"]); if (id == 0) { ; } else { DataTable dataTable = SQLOperate.GetAreaInfoById(id); lblAreaId.Text = dataTable.Rows[0]["AreaId"].ToString(); lblAreaName.Text = dataTable.Rows[0]["AreaName"].ToString(); lblParentId.Text = dataTable.Rows[0]["ParentId"].ToString(); } } /// <summary> /// 删除地区 /// </summary> /// <param name="sender"></param> /// <param name="e"></param> protected void btnDel_Click(object sender, EventArgs e) { int id = Convert.ToInt32(Request.QueryString["id"]); if (id == 0) { Response.Write("<mce:script type="text/javascript"></mce:script>"); } else { if (SQLOperate.CheckNextClass(id)) Response.Write("<mce:script type="text/javascript"></mce:script>"); else { int result = SQLOperate.DeleteClass(id); if (result > 0) { Response.Write("<mce:script type="text/javascript"></mce:script>"); } } } } /// <summary> /// 修改地区名 /// </summary> /// <param name="sender"></param> /// <param name="e"></param> protected void btnModify_Click(object sender, EventArgs e) { int id = Convert.ToInt32(Request.QueryString["id"]); if (id == 0) { Response.Write("<mce:script type="text/javascript"></mce:script>"); } else { DataTable dataTable = SQLOperate.GetAreaInfoById(id); int result = SQLOperate.ModifyClass(Convert.ToInt32(dataTable.Rows[0]["AreaId"].ToString()), txtAreaName.Text.ToString().Trim()); if (result > 0) Response.Write("<mce:script type="text/javascript"></mce:script>"); } } /// <summary> /// 添加同级地区 /// </summary> /// <param name="sender"></param> /// <param name="e"></param> protected void btnAddParityClass_Click(object sender, EventArgs e) { int id = Convert.ToInt32(Request.QueryString["id"]); if (id == 0) { Response.Write("<mce:script type="text/javascript"></mce:script>"); } else { DataTable dataTable = SQLOperate.GetAreaInfoById(id); int result = SQLOperate.AddParityClass(Convert.ToInt32(dataTable.Rows[0]["ParentId"].ToString()), txtAreaName.Text.ToString().Trim()); if (result > 0) Response.Write("<mce:script type="text/javascript"></mce:script>"); } } /// <summary> /// 添加子级地区 /// </summary> /// <param name="sender"></param> /// <param name="e"></param> protected void btnAddNextClass_Click(object sender, EventArgs e) { int id = Convert.ToInt32(Request.QueryString["id"]); if (id == 0) { Response.Write("<mce:script type="text/javascript"></mce:script>"); } else { DataTable dataTable = SQLOperate.GetAreaInfoById(id); int result = SQLOperate.AddNextClass(Convert.ToInt32(dataTable.Rows[0]["AreaId"].ToString()), txtAreaName.Text.ToString().Trim()); if (result > 0) Response.Write("<mce:script type="text/javascript"></mce:script>"); } }}

此程序只为入门者参考，如果更好的实现，欢迎留言补充，共同学习...