asp.net用sql数据库生成json字符串并显示出来

use Shop
create table DictBase(Id int identity(1,1) primary key,Name nchar(10))

insert into DictBase
select  '包装'
UNION ALL
select  '价格'
UNION ALL
select  '品牌'

工厂方法模式

IDAL层（添加一个IDictBase接口，在里面定义一个方法）

using System;
using System.Collections.Generic;
using System.Data;
namespace Letao.IDAL
{
    /// <summary>
    /// 接口：类别字典键
    /// </summary>
    public interface IDictBase
    {
　　　　#region  获取
        /// <summary>
        /// 获取所有字典键名
        /// </summary>
        List<Model.DictBase> Get();
        #endregion
    } 
}

DALFactory层（DataAccess新建接口实现工厂模式CreateDictBase）

using System;
using System.Reflection;
using System.Configuration;
using Letao.IDAL;
namespace Letao.DALFactory
{
    /// <summary>
    /// 工厂反射层
    /// </summary>
    public sealed class DataAccess
    {
        private static readonly string AssemblyPath = ConfigurationManager.AppSettings["SQLServerDAL"];
 /// <summary>
        /// 类别字典键名
        /// </summary>
        public static Letao.IDAL.IDictBase CreateDictBase()
        {

            string ClassNamespace = AssemblyPath + ".DictBase";
            return (IDictBase)Assembly.Load(AssemblyPath).CreateInstance(ClassNamespace);
        }
    }
}

SQLServerDAL层（在项目中添加类DictBase，继承自接口IDictBase，实现的方法是向控制台输出所有字典键名）

using System;
using System.Data;
using System.Data.SqlClient;
using System.Collections.Generic;

namespace Letao.SQLServerDAL
{
    /// <summary>
    /// 类别字典键
    /// </summary>
    class DictBase:IDAL.IDictBase
    {
　　　　 #region 获取
        /// <summary>
        /// 获取所有字典键名
        /// </summary>
        public List<Model.DictBase>  Get()
        {
            string sql = string.Format("select * from DictBase");
            List<Model.DictBase> list = new List<Model.DictBase>();
            using(SqlDataReader dr=DBUtility.DbHelperSQL.ExecuteReader(ConnString.connReadonly,CommandType.Text,sql,null))
            {
                while(dr.Read())
                {
                    Model.DictBase model = new Model.DictBase();
                    object obj;
                    obj = dr["Id"];
                    if(obj!=null &&obj!=DBNull.Value)
                    {
                        model .Id =(int )obj;
                    }
                    model.Name = dr["Name"].ToString();
                    list.Add(model );
                }
            }
            return list;
        }
    }
}

BLL层（创建一个DictBase的工厂类，使它继承自CreateDictBase接口，创建一个方法，使它的返回值为IDictBase，最后在方法的实现里面返回实例化的DictBase）

using System;
using System.Collections.Generic;
namespace Letao.BLL
{
    /// <summary>
    /// 类别字典键
    /// </summary>
    public  class DictBase
    {
        protected static Letao.IDAL.IDictBase dal =Letao .DALFactory .DataAccess.CreateDictBase();
 /// <summary>
        /// 获取所有字典键名
        /// </summary>        
        public static List<Model.DictBase> Get()
        {
            return dal.Get();
        }
    }
}

Model层（DictBase类）

using System;
namespace Letao.Model
{
    /// <summary>
    /// 类别字典键
    /// </summary>    
    public  class DictBase
    {    
        /// <summary>
        /// 字典健名编号
        /// </summary>
        public int Id { get; set; }        
        /// <summary>
        /// 字典关键字
        /// </summary>
        public string Name{ get; set; }
    }
}

---

---

 备注：

DBUtility层（DbHelperSQL类、ConnString类）

using System;
using System.Data;
using System.Data.SqlClient;
namespace Letao.DBUtility
{
    public class DbHelperSQL
    {
 　　　　/// <summary>
        /// 返回数据内容（SqlDataReader）
        /// </summary>
        /// <param name="connectionString">数据库连接字符串</param>
        /// <param name="cmdType">执行类型（过程/语句）</param>
        /// <param name="cmdText">执行的过程名称/查询语句</param>
        /// <param name="commandParameters">command执行的SqlParameter[]数组</param>
        /// <returns>SqlDataReader 返回执行后的数据内容</returns>
        public static SqlDataReader ExecuteReader(string connectionString, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
        {
            SqlCommand cmd = new SqlCommand();
            SqlConnection conn = new SqlConnection(connectionString);
            try
            {
                PrepareCommand(cmd, conn, null, cmdType, cmdText, commandParameters);
                SqlDataReader rdr = cmd.ExecuteReader(CommandBehavior.CloseConnection);
                cmd.Parameters.Clear();
                return rdr;
            }
            catch
            {
                //Close(conn);
                //Dispose(conn);
                throw;
            }
        }
    }
}

using System;
namespace Letao.SQLServerDAL
{
    /// <summary>
    /// 数据库连接字符串
    /// </summary>
    class ConnString
    {
        /// <summary>
        /// 读写数据库连接字符串
        /// </summary>        
        public static string conn
        {
            get
            {
                if (_conn == null)
                {
                    _conn = System.Configuration.ConfigurationManager.ConnectionStrings["ConnectionStringWrite"].ToString();
                }
                return _conn;
            }
        }
        private static string _conn = null;
        /// <summary>
        /// 只读数据库连接字符串
        /// </summary>
        public static string connReadonly
        {
            get
            {
                if (_connReadonly == null)
                {
                    _connReadonly = System.Configuration.ConfigurationManager.ConnectionStrings["ConnectionStringReadonly"].ToString();
                }
                return _connReadonly;
            }
        }
        private static string _connReadonly = null;
    }
}

接下来添加App.config文件，来实现系统所选择的数据库是什么数据库

<?xml version="1.0"?>

<appSettings>
    <add key="title" value="乐淘"/>
    <add key="SQLServerDAL" value ="Letao.SQLServerDAL"/>
</appSettings>

 页面

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
    <script src="/Admin/Scripts/jquery-1.8.3.min.js" type="text/javascript"></script>
</head>
<body>  
    <div>
     <ul id="dictbase"></ul>
    </div>
    <script type="text/javascript">
        $(function () {
            $.getJSON('test.aspx?action=get', function (json) {              
                var _html = [];
                for (var key in json) {
                    _html.push('<li data="' + json[key].Id + '">' + json[key].Name + '</li>');
                }
                $("#dictbase").empty().append(_html.join(''));
            });
        })
    </script>
</body>
</html>

 protected void Page_Load(object sender, EventArgs e)
    {
        if (Request.Headers["X-Requested-With"] != null && Request.Headers["X-Requested-With"].ToLower() == "XMLHttpRequest".ToLower())
        {
            Response.Clear();
            Response.ContentType = "application/json";
            if (Request["action"] == "get")
                Response.Write(GetJson()); 
            Response.End();
        }
    }
    protected string GetJson()
    {
        System.Web.Script.Serialization.JavaScriptSerializer json = new System.Web.Script.Serialization.JavaScriptSerializer();
        List<Letao.Model.DictBase> list = new List<Letao.Model.DictBase>();
        list = Letao.BLL.DictBase.Get();     
        return json.Serialize(list);
    }

效果

知识点：

1、从数据库转换成json字符串

2、X-Requested-With是否是第一次加载

谷歌浏览器审查元素后的结果

参考网址：1、ASP.NET用SQL Server中的数据来生成JSON字符串

http://www.cnblogs.com/jacksonwj/archive/2008/08/10/1264525.html

2、asp.net 简单工厂模式和工厂方法模式之论述 

  http://www.jb51.net/article/29212.htm