对《treeview的非常规绑定》中的第一种显示的改进，以及第二种的显示方法

在这次改进中，减少了对数据库的操作。每个treeview 的绑定只对数据库进行了三次操作。即对三个表的读取。以加快浏览速度。
写了一个类，
SqlOperate.cs

  1using System;
  2using System.Data;
  3using System.Data.SqlClient;
  4using System.Configuration;
  5
  6
  7namespace ForProjectTest
  8{
  9    /**//// <summary>
 10    /// SqlOperate 的摘要说明。
 11    /// </summary>
 12    public class SqlOperate
 13    {
 14        public SqlOperate()
 15        {
 16            //
 17            // TODO: 在此处添加构造函数逻辑
 18            //
 19        }
 20
 21
 22
 23        protected static string SqlConnection=ConfigurationSettings.AppSettings["con"];
 24
 25        /**//// <summary>
 26        /// 
 27        /// </summary>
 28        /// <param name="SqlString"></param>
 29        /// <returns></returns>
 30        public static DataSet ds(string SqlString)
 31        {
 32            SqlConnection con = new SqlConnection(SqlConnection);
 33            SqlDataAdapter sda = new SqlDataAdapter();
 34            sda.SelectCommand = new SqlCommand(SqlString,con);
 35            DataSet ds = new DataSet();
 36            sda.Fill(ds);
 37            con.Close();
 38            con.Dispose();
 39            sda.Dispose();
 40            return ds;
 41        }    
 42
 43
 44        /**//// <summary>
 45        /// 旧表里符合条件的行组合成新表（旧表只限于三列）
 46        /// </summary>
 47        /// <param name="OldDT">旧表</param>
 48        /// <param name="liehao">列的索引</param>
 49        /// <param name="tiaojian">字段值</param>
 50        /// <returns></returns>
 51        public static DataTable RNewDT(DataTable OldDT,int liehao,string tiaojian)
 52        {
 53            DataTable NewDT=new DataTable();
 54            NewDT.Columns.Add("class_dep_code");
 55            NewDT.Columns.Add("class_name");
 56            NewDT.Columns.Add("class_code");
 57            int RowCount = OldDT.Rows.Count;
 58            for(int i=0;i<RowCount;i++)
 59            {
 60                string cellText = OldDT.Rows[i][liehao].ToString();
 61                if(cellText==tiaojian)
 62                {
 63                    DataRow NewRow =NewDT.NewRow();
 64                    NewRow["class_dep_code"]=OldDT.Rows[i][0].ToString();
 65                    string aa = OldDT.Rows[i][0].ToString();
 66                        
 67                    NewRow["class_name"]=OldDT.Rows[i][1].ToString();
 68                    string bb = OldDT.Rows[i][1].ToString();
 69                            
 70                    NewRow["class_code"]=OldDT.Rows[i][2].ToString();
 71                    string cc = OldDT.Rows[i][2].ToString();
 72                            
 73                    NewDT.Rows.Add(NewRow);
 74
 75                }
 76            }
 77            return NewDT;
 78        }
 79
 80        /**//// <summary>
 81        /// 判断是否包含二级节点
 82        /// </summary>
 83        /// <param name="dt">表</param>
 84        /// <param name="tiaojian">字段值</param>
 85        /// <returns></returns>
 86        public static bool IsNotConclude(DataTable dt,string tiaojian)
 87        {
 88            int RowCount = dt.Rows.Count;
 89            string all=null;
 90
 91            for(int i=0;i<RowCount;i++)
 92            {
 93                string cellText = dt.Rows[i][0].ToString();
 94                if(tiaojian==cellText)
 95                {
 96                    all=all+cellText;
 97                }
 98            }
 99            if(all==null)
100            {
101                return false;
102            }
103            else
104            {
105                return true;
106            }
107        }
108
109        /**//// <summary>
110        /// 查询单个数值
111        /// </summary>
112        /// <param name="SqlString">sql语句</param>
113        /// <returns></returns>
114        public static string FirstString(string SqlString)
115        {
116            SqlConnection con = new SqlConnection(SqlConnection);
117            con.Open();
118            SqlCommand cmd = new SqlCommand(SqlString,con);
119            string frist = Convert.ToString(cmd.ExecuteScalar());
120            con.Close();
121            con.Dispose();
122            return frist;
123        }
124
125        /**//// <summary>
126        /// 查询单个数值
127        /// </summary>
128        /// <param name="SqlString">sql语句</param>
129        /// <returns></returns>
130        public static int FirstInt(string SqlString)
131        {
132            SqlConnection con = new SqlConnection(SqlConnection);
133            con.Open();
134            SqlCommand cmd = new SqlCommand(SqlString,con);
135            Object fristObj = cmd.ExecuteScalar();
136            con.Close();
137            con.Dispose();
138            if(fristObj==DBNull.Value)
139            {
140                return 0;
141            }
142            else
143            {
144                return Convert.ToInt32(fristObj);
145            }
146        }
147
148
149
150    }
151}
152

以下是页面代码：
TreeView3是第一种显示方法，TreeView1是第二种显示方法

  1using System;
  2using System.Collections;
  3using System.ComponentModel;
  4using System.Data;
  5using System.Drawing;
  6using System.Web;
  7using System.Web.SessionState;
  8using System.Web.UI;
  9using System.Web.UI.WebControls;
 10using System.Web.UI.HtmlControls;
 11using Microsoft.Web.UI.WebControls;
 12
 13using System.Data.SqlClient;
 14
 15namespace ForProjectTest
 16{
 17    /**//// <summary>
 18    /// TreeviewBind 的摘要说明。
 19    /// </summary>
 20    public class TreeviewBind : System.Web.UI.Page
 21    {
 22        protected Microsoft.Web.UI.WebControls.TreeView TreeView1;
 23
 24        protected Microsoft.Web.UI.WebControls.TreeView TreeView3;
 25
 26    
 27        private void Page_Load(object sender, System.EventArgs e)
 28        {
 29            
 30            // 在此处放置用户代码以初始化页面
 31        }
 32
 33        
 34
 35        Web 窗体设计器生成的代码#region Web 窗体设计器生成的代码
 36        override protected void OnInit(EventArgs e)
 37        {
 38            //
 39            // CODEGEN: 该调用是 ASP.NET Web 窗体设计器所必需的。
 40            //
 41            InitializeComponent();
 42            base.OnInit(e);
 43        }
 44        
 45        /**//// <summary>
 46        /// 设计器支持所需的方法 - 不要使用代码编辑器修改
 47        /// 此方法的内容。
 48        /// </summary>
 49        private void InitializeComponent()
 50        {    
 51            this.TreeView3.PreRender += new System.EventHandler(this.TreeView3_PreRender);
 52            this.TreeView1.PreRender += new System.EventHandler(this.TreeView1_PreRender);
 53            this.Load += new System.EventHandler(this.Page_Load);
 54
 55        }
 56        #endregion
 57
 58
 59        private void TreeView3_PreRender(object sender, System.EventArgs e)
 60        {
 61            TreeNode tmpNd;//一级节点声明
 62            TreeNode tmpNd2;//二级节点声明
 63            TreeNode tmpNd3;//三级节点（包含于二级节点中）
 64            TreeNode tmpNd4;//三级节点（不包含于二级节点）
 65    
 66            
 67            string sqlSelect = "select dep_name,dep_code from db_dep";
 68            DataView dv =SqlOperate.ds(sqlSelect).Tables[0].DefaultView;
 69            string sqlSelect2 = "select unit_name,unit_code from db_unit";
 70            DataView dv3 = SqlOperate.ds(sqlSelect2).Tables[0].DefaultView;
 71            //把db_class表存入内存中
 72            string sqlSelect3 = "select class_dep_code,class_name,class_code from db_class";
 73            DataTable dt = SqlOperate.ds(sqlSelect3).Tables[0];
 74            // 用于添加一级节点的foreach语句
 75            foreach(DataRowView drv in dv)
 76            {
 77                //给每个一级节点赋值
 78                
 79                tmpNd = new TreeNode();
 80                tmpNd.ID=drv["dep_code"].ToString();
 81                tmpNd.Text=drv["dep_name"].ToString();
 82                //判断当前节点是否存在二级节点,如果存在则增加二级节点，并添加三级节点
 83                if(SqlOperate.IsNotConclude(dt,tmpNd.ID.ToString()))
 84                {
 85                    //添加二级节点的foreach语句
 86                    
 87                    DataView dv2 = SqlOperate.RNewDT(dt,0,tmpNd.ID.ToString()).DefaultView;
 88                    foreach(DataRowView drv2 in dv2)
 89                    {
 90                        tmpNd2 = new TreeNode();
 91                        tmpNd2.ID=drv2["class_code"].ToString();
 92                        tmpNd2.Text=drv2["class_name"].ToString();
 93                        //添加三级节点的foreach语句
 94                        
 95                        foreach(DataRowView drv3 in dv3)
 96                        {
 97                            tmpNd3 = new TreeNode();
 98                            tmpNd3.ID = drv3["unit_code"].ToString();
 99                            tmpNd3.Text = drv3["unit_name"].ToString();
100                            tmpNd2.Nodes.Add(tmpNd3);
101                        }
102                        
103                        //添加二级节点
104                        tmpNd.Nodes.Add(tmpNd2);
105                    }
106                    
107                }
108                //如果不存在，直接添加三级节点（实际上在此层是二级节点）
109                else
110                {
111                    foreach(DataRowView drv3 in dv3)
112                    {
113                        tmpNd4 = new TreeNode();
114                        tmpNd4.ID = drv3["unit_code"].ToString();
115                        tmpNd4.Text = drv3["unit_name"].ToString();
116                        tmpNd.Nodes.Add(tmpNd4);
117                    }
118                }
119                //添加一级节点
120                this.TreeView3.Nodes.Add(tmpNd);
121                
122            }
123            
124        }
125
126        private void TreeView1_PreRender(object sender, System.EventArgs e)
127        {
128            TreeNode tmpNd;//一级节点的声明；
129            TreeNode tmpNd2;//二级节点的声明；
130            TreeNode tmpNd4;//三级节点的声明；
131
132            //添加一级节点
133            string SqlString = "select unit_code,unit_name from db_unit";
134            DataView dv = SqlOperate.ds(SqlString).Tables[0].DefaultView;
135
136            string SqlString2 = "select dep_code,dep_name from db_dep";
137            DataView dv2 = SqlOperate.ds(SqlString2).Tables[0].DefaultView;
138
139            string SqlString3 = "select class_dep_code,class_name,class_code from db_class";
140            DataTable dt = SqlOperate.ds(SqlString3).Tables[0];
141
142
143            foreach(DataRowView drv in dv)
144            {
145                tmpNd = new TreeNode();
146                tmpNd.ID = drv["unit_code"].ToString();
147                tmpNd.Text = drv["unit_name"].ToString();
148                //添加二级节点
149                
150                foreach(DataRowView drv2 in dv2)
151                {
152                    tmpNd2 = new TreeNode();
153                    tmpNd2.ID = drv2["dep_code"].ToString();
154                    tmpNd2.Text = drv2["dep_name"].ToString();
155
156                    
157                    if(SqlOperate.IsNotConclude(dt,tmpNd2.ID.ToString()))
158                    {
159                        //添加三级节点
160                        DataView dv4 = SqlOperate.RNewDT(dt,0,tmpNd2.ID.ToString()).DefaultView;
161                        foreach(DataRowView drv4 in dv4)
162                        {
163                            tmpNd4 = new TreeNode();
164                            tmpNd4.ID = drv4["class_code"].ToString();
165                            tmpNd4.Text = drv4["class_name"].ToString();
166                            tmpNd2.Nodes.Add(tmpNd4);
167                        }
168                    }
169                    tmpNd.Nodes.Add(tmpNd2);
170                }
171                this.TreeView1.Nodes.Add(tmpNd);
172            }
173            
174        }
175    }
176}
177