简单三层复习

好久没复习了，以前学的，不复习的话，会遗忘，所以还是多复习多学习！废话不多说，开始～～～～

首先数据库脚本：

USE [DB_MyStudentLife]
GO

/****** Object:  Table [dbo].[MyClass]    Script Date: 11/26/2015 22:19:31 ******/
SET ANSI_NULLS ON
GO

SET QUOTED_IDENTIFIER ON
GO

CREATE TABLE [dbo].[MyClass](
[C_ID] [INT] NOT NULL,
[C_Name] [NVARCHAR](200) NOT NULL,
[C_Descr] [NVARCHAR](MAX) NOT NULL,
PRIMARY KEY CLUSTERED
(
[C_ID] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
) ON [PRIMARY]

GO

然后是实体层代码：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Entity
{
public class ClassEntity
{
/// <summary>
/// 班级编号
/// </summary>
public int CID { get; set; }

/// <summary>
/// 班级名称
/// </summary>
public string CName { get; set; }

/// <summary>
/// 班级描述
/// </summary>
public string CDescription { get; set; }
}
}

然后是DAL层：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Configuration;
using System.Data;
using System.Data.SqlClient;

namespace DAL
{
public class SQLHelper
{
/// <summary>
/// 获取连接字符串
/// </summary>
public static string ConnectionString
{
get { return ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString; }
}

/// <summary>
/// 获取Datatable数据
/// </summary>
/// <param name="sql">SQL语句</param>
/// <param name="type">命令类型</param>
/// <param name="param">参数列表</param>
/// <returns>返回DataTable类型</returns>
public static DataTable GetDataTable(string sql,CommandType type,params SqlParameter[] param)
{
//创建连接对象
using (SqlConnection conn = new SqlConnection(ConnectionString))
{
//创建数据适配器对象
using (SqlDataAdapter sda = new SqlDataAdapter(sql, conn))
{
if(param!=null)
{
sda.SelectCommand.Parameters.AddRange(param);
}

sda.SelectCommand.CommandType = type;

DataTable table = new DataTable();

sda.Fill(table);

return table;

}
}
}
}
}

using Entity;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Data;
using System.Data.SqlClient;

namespace DAL
{
public class ClassDAL
{
/// <summary>
/// 获取班级列表数据
/// </summary>
/// <returns></returns>
public List<ClassEntity> GetList()
{
string sql = "SELECT * FROM dbo.MyClass;";

DataTable table = SQLHelper.GetDataTable(sql, CommandType.Text);

//此处不能直接new一个对象
List<ClassEntity> classListModel = null;

//table不为空
if (table.Rows.Count > 0)
{
//要在这里new ,创建对象
classListModel = new List<ClassEntity>();

ClassEntity model = null;
foreach (DataRow row in table.Rows)
{
model = new ClassEntity();
//加载数据
LoadEntity(row, model);
classListModel.Add(model);
}

}
return classListModel;

}

/// <summary>
/// 加载数据
/// </summary>
/// <param name="row"></param>
/// <param name="model"></param>
public void LoadEntity(DataRow row, ClassEntity model)
{
if (row["C_ID"] != null)
{
model.CID = Convert.ToInt32(row["C_ID"]);
}
if (row["C_Name"] != null)
{
model.CName = row["C_Name"].ToString();
}
if (row["C_Descr"] != null)
{
model.CDescription = row["C_Descr"].ToString();
}
}
}
}

然后是BLL层：

using DAL;
using Entity;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace BLL
{
public class ClassBLL
{
ClassDAL dal = new ClassDAL();

/// <summary>
/// 获取Class列表
/// </summary>
/// <returns></returns>
public List<ClassEntity> GetList()
{
return dal.GetList();
}
}
}

然后是Web项目：

using BLL;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

namespace Web
{
public partial class Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
ClassBLL bll = new ClassBLL();
GridView1.DataSource= bll.GetList();
GridView1.DataBind();
}
}
}

效果图：



DAL层的代码，表红色的部分，需要注意，如果实例化的位置出错了，就会得到下面的结果：