三层架构实例

这里以查询数据库中student表的所有信息为例：

1、模型层，Student.cs文件：

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

namespace SchoolModels

{

public class Student

{

public Student()

{ }

public Student(int id, string name, string pwd, int age, string sex) {

this.StudentId = id;

this.StudentName = name;

this.StudentPwd = pwd;

}

private int studentId;

public int StudentId

{

get { return studentId; }

set { studentId = value; }

}

private string studentName;

public string StudentName

{

get { return studentName; }

set { studentName = value; }

}

private string studentPwd;

public string StudentPwd

{

get { return studentPwd; }

set { studentPwd = value; }

}

}

}

2、数据访问层，StudentService.cs文件：using System.Text;

using System.Data;

using System.Data.SqlClient;

using SchoolModels;

namespace SchoolDal

{

public class StudentService

{

public static IList GetAllStudents()

{

List stus = new List();

string sql = "select * from student";

SqlCommand cmd = new SqlCommand(sql, DBHelper.con);

DBHelper.con.Open();

SqlDataReader reader = cmd.ExecuteReader();

while (reader.Read())

{

Student student = new Student();

student.StudentId = (int)reader["StudentId"];

student.StudentName = reader["StudentName"].ToString();

student.StudentPwd = reader["StudentPwd"].ToString();

stus.Add(student);

}

reader.Close();

DBHelper.con.Close();

return stus;

}

}

其中，里面有一个DBHelper.cs文件：

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Configuration;

using SchoolModels;

using System.Data;

using System.Data.SqlClient;

namespace SchoolDal

{

public class DBHelper

{

public static string conStr = ConfigurationManager.ConnectionStrings["conDb"].ToString();

public static SqlConnection con = new SqlConnection(conStr); }

}

3、业务逻辑层，StudentManager.cs文件：

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using SchoolDal;

using SchoolModels;

namespace SchoolBll

{

public class StudentManager

{

public static IList GetAllStudents()

{

return StudentService.GetAllStudents();

}

}

}