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  • 手把手教你做下拉菜单篇

    此文章由本人以爱像深蓝3313576 首发于龙族社区,如需转载请注明出处!

    市面上讲述下拉菜单的文章多如牛毛,且使用下拉菜单的网站也非常之多,但在下看来,90%的网站和教程使用了如下代码:
     function MM_reloadPage(init) {  //reloads the window if Nav4 resized
      if (init==true) with (navigator) {if ((appName=="Netscape")&&(parseInt(appVersion)==4)) {
        document.MM_pgW=innerWidth; document.MM_pgH=innerHeight; onresize=MM_reloadPage; }}
      else if (innerWidth!=document.MM_pgW || innerHeight!=document.MM_pgH) location.reload();
    }
    MM_reloadPage(true);
    // -->

    function MM_findObj(n, d) { //v4.0
      var p,i,x;  if(!d) d=document; if((p=n.indexOf("?"))>0&&parent.frames.length) {
        d=parent.frames[n.substring(p+1)].document; n=n.substring(0,p);}
      if(!(x=d[n])&&d.all) x=d.all[n]; for (i=0;!x&&i<d.forms.length;i++) x=d.forms[i][n];
      for(i=0;!x&&d.layers&&i<d.layers.length;i++) x=MM_findObj(n,d.layers[i].document);
      if(!x && document.getElementById) x=document.getElementById(n); return x;
    }

    function MM_showHideLayers() { //v3.0
      var i,p,v,obj,args=MM_showHideLayers.arguments;
      for (i=0; i<(args.length-2); i+=3) if ((obj=MM_findObj(args[i]))!=null) { v=args[i+2];
        if (obj.style) { obj=obj.style; v=(v=='show')?'visible':(v='hide')?'hidden':v; }
        obj.visibility=v; }
    }

    在下因公司的一个项目需要学习完ajax这个最流行的web技术之后,独辟蹊径想出一个集完全无刷新实时更新的下拉菜单,而且这个下拉菜单可以无限的可扩展性.下面请看源码:
    1.数据库,为了方便大家下载,在下所使用的是access,即想学习的朋友可以直接下载我包含数据库mdb文件的rar包,解压至IIS的发布目录即可直接查看效果.
    2.表结构如下图:

    3.在下使用的是最传统的两层结构:
    数据库连接层DAL,Model数据模型层
    DAL  db.cs源码:
    using System;
    using System.Data;
    using System.Configuration;
    using System.Web;
    using System.Web.Security;
    using System.Web.UI;
    using System.Web.UI.WebControls;
    using System.Web.UI.WebControls.WebParts;
    using System.Web.UI.HtmlControls;
    using System.Data.OleDb;
    using System.IO;

    /// <summary>
    /// DB 的摘要说明
    /// </summary>
    public class DB
    {
        private string strConn = System.Configuration.ConfigurationSettings.AppSettings["strConn"] + AppDomain.CurrentDomain.BaseDirectory + System.Configuration.ConfigurationSettings.AppSettings["strDBPath"];
        private OleDbConnection cn = null;
        public DB()
        {
            try
            {
                cn = new OleDbConnection(strConn);
            }
            catch (OleDbException oe)
            {
                Console.Write(oe.Message);
            }
        }

        /// <summary>
        /// 通过Sql脚本执行数据库增,删,改操作
        /// </summary>
        /// <param name="strSql">Sql脚本</param>
        /// <returns>true表示执行成功,false表示执行失败</returns>
        public bool ExecCmdBySql(string strSql)
        {
            bool foo = true;

            try
            {
                cn.Open();
                OleDbCommand cmd = new OleDbCommand();
                cmd.CommandText = strSql;
                cmd.Connection = cn;
                cmd.ExecuteNonQuery();
            }
            catch (OleDbException oe)
            {
                foo = false;
                Console.Write(oe.Message);
            }
            finally
            {
                cn.Close();//关闭接连
            }

            return foo;
       
        }

       
        /// <summary>
        /// 通过查询得到数据集
        /// </summary>
        /// <param name="strSql">查询Sql脚本</param>
        /// <param name="ds">数据集引用</param>
        /// <param name="tableName">表名</param>
        /// <returns>true表示成功查询得到数据集,false表示查询失败</returns>
        public bool GetDataSetByQuery(string strSql,ref DataSet ds,string tableName)
        {
            bool foo = true;
            try
            {
                cn.Open();
                OleDbCommand cmd = new OleDbCommand();
                cmd.CommandText = strSql;
                cmd.Connection = cn;
                OleDbDataReader reader = cmd.ExecuteReader();
                ds.Load(reader, LoadOption.OverwriteChanges, new string[] { tableName });
            }
            catch (OleDbException oe)
            {
                foo = false;
                Console.Write(oe.Message);
            }
            finally
            {
                cn.Close();
            }

            return foo;
        }

        /// <summary>
        /// 通过查询得到首行数据编号
        /// </summary>
        /// <param name="strSql">Sql脚本</param>
        /// <param name="id">编号</param>
        /// <returns></returns>
        public bool GetScalarByQuery(string strSql, ref long id)
        {
            bool foo = true;
            try
            {
                cn.Open();
                OleDbCommand cmd = new OleDbCommand();
                cmd.CommandText = strSql;
                cmd.Connection = cn;
                Object obj = cmd.ExecuteScalar();
                if (!obj.ToString().Equals(""))
                {
                    id = (long)obj;
                }
                else
                {
                    id = 1;
                }
            }
            catch (OleDbException oe)
            {
                foo = false;
                Console.Write(oe.Message);
            }
            finally
            {
                cn.Close();
            }

            return foo;
        }

    }

    注:只考虑access数据库Sql连接的情况故有三个方法;

    model层: CMenu类

    using System;
    using System.Data;
    using System.Configuration;
    using System.Web;
    using System.Web.Security;
    using System.Web.UI;
    using System.Web.UI.WebControls;
    using System.Web.UI.WebControls.WebParts;
    using System.Web.UI.HtmlControls;

    /// <summary>
    /// CMenu 的摘要说明
    /// </summary>
    public class CMenu
    {
        private long menu_id; //菜单编号
        private string menu_name;//菜单名称
        private long menu_parentID;//父级菜单编号
        public long Menu_id
        {
            get { return menu_id; }
            set { menu_id = value; }
        }
        public string Menu_name
        {
            get { return menu_name; }
            set { menu_name = value; }
        }
        public long Menu_parentID
        {
            get { return menu_parentID; }
            set { menu_parentID = value; }
        }
        public CMenu()
     {
            menu_id = -1; //菜单编号
            menu_name = "";//菜单名称
            menu_parentID = -1;//父级菜单编号
     }

        /// <summary>
        /// 得到当前记录应该插入的编号
        /// </summary>
        /// <returns>true表示执行成功,false表示执行失败</returns>
        public bool GetID()
        {
            bool foo = false;
           
            DB db = new DB();

            string strSql = "select max(menu_id) from menu";


            if (db.GetScalarByQuery(strSql, ref menu_id))
            {
                foo = true;
            }

            return foo;
        }

        public bool Insert2DB()
        {
            bool foo = false;

            if (!GetID())
            {
                return foo;
            }

            string strSql = "insert into menu ";
            string strAttribute = " (menu_id";
            string strValue = " (" + menu_id;

            if (!menu_name.Equals(""))
            {
                strAttribute += " ,menu_name";
                strValue += ",'" + menu_name + "'";
            }

            if (-1 != menu_parentID)
            {
                strAttribute += " ,menu_parentID";
                strValue += "," + menu_parentID;
            }

            strAttribute += ")";
            strValue += ")";
            strSql += strAttribute + strValue;

            DB db = new DB();

            if (db.ExecCmdBySql(strSql))
            {
                foo = true;
            }

            return foo;
        }

        public bool Delete2DB()
        {
            bool foo = false;

            string strSql = "delete from menu where menu_id = " + menu_id;

            DB db = new DB();

            if (db.ExecCmdBySql(strSql))
            {
                foo = true;
            }

            return foo;
        }

        public bool Delete2DB(string strConn)
        {
            bool foo = false;

            string strSql = "delete from menu " + strConn;

            DB db = new DB();

            if (db.ExecCmdBySql(strSql))
            {
                foo = true;
            }

            return foo;

        }

        public bool Update2DB()
        {
            bool foo = false;

            string strSql = "update menu set menu_id = menu_id ";

            if (!menu_name.Equals(""))
            {
                strSql += " menu_name = '" + menu_name + "'";
            }

            if (-1 != menu_parentID)
            {
                strSql += " menu_parentID = " + menu_parentID;
            }

            strSql += " where menu_id =" + menu_id ;

            DB db = new DB();

            if (db.ExecCmdBySql(strSql))
            {
                foo = true;
            }

            return foo;
        }

        public bool Query2DB(ref DataSet ds,string strColunm ,string strConn)
        {
            bool foo = false;

            string strSql = "select * from ";

            if (!strColunm.Equals(""))
            {
                strSql ="select " + strColunm + " from menu ";
            }

            if (!strConn.Equals(""))
            {
                strSql += strConn;
            }

            DB db = new DB();

            if (db.GetDataSetByQuery(strSql, ref ds, "menu"))
            {
                foo = true;
            }

            return foo;
        }

    }
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  • 原文地址：https://www.cnblogs.com/shinefzh/p/1129804.html
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