第一次尝试三层架构<实现简单的增、删、查、改>

三层架构：UI（界面，User Interfa）、BLL（业务逻辑层）以及DAL（数据访问层）。三层之间通过Model实现数据的传递。在使用中牢记，三层之间的访问权限;UI→BLL→DAL。

采用三层架构的优点：高可拓展性、可维护性高，不足之处：工作量大、系统比较复杂(感觉最好是精通设计思想,如设计模式)、效率比较低。

项目的结构图：

建立相应的文件夹

首先配置应用程序配置文件 App.config

配置如下：

View Code

1 <?xml version="1.0" encoding="utf-8" ?>
2 <configuration>
3   <connectionStrings>
4     <add name="cons" connectionString="server=(local);user id=sa; pwd=********;database=GUbase"/>//连接字符串
5   </connectionStrings>
6 </configuration>

封装的数据库操作SQlHelper.cs

View Code

 1 sing System;
 2 using System.Collections.Generic;
 3 using System.Linq;
 4 using System.Text;
 5 using System.Configuration;
 6 using System.Data.SqlClient;
 7 using System.Data;
 8 
 9 namespace 三层架构.DAL
10 {
11     class SQlHelper
12     {
13         private static readonly string cons = ConfigurationManager.ConnectionStrings["cons"].ConnectionString;//读取配置文件的连接字符串
14 
15         #region ExecuteNoQuery//用于执行非查询语句
16         /// <summary>
17         /// ExecuteNoQuery
18         /// </summary>
19         /// <param name="sql">sql语句</param>
20         /// <param name="Parameters">参数</param>
21         /// <returns></returns>
22         public static int ExecuteNoQuery(string sql, params SqlParameter[] Parameters)
23         {
24             using (SqlConnection con = new SqlConnection(cons))
25             {
26                 con.Open();
27                 using (SqlCommand cmd = con.CreateCommand())
28                 {
29                     cmd.CommandText = sql;
30                     cmd.Parameters.AddRange(Parameters);
31                     return cmd.ExecuteNonQuery();
32                 }
33             }
34 
35         } 
36         #endregion
37         #region  ExecuteScalar
38         /// <summary>
39         ///  ExecuteScalar//查询相关
40         /// </summary>
41         /// <param name="sql">sql语句</param>
42         /// <param name="Parameters">参数/param>
43         /// <returns></returns>
44         public static object ExecuteScalar(string sql, params SqlParameter[] Parameters)
45         {
46             using (SqlConnection con = new SqlConnection(cons))
47             {
48                 con.Open();
49                 using (SqlCommand cmd = con.CreateCommand())
50                 {
51                     cmd.CommandText = sql;
52                     cmd.Parameters.AddRange(Parameters);
53                     return cmd.ExecuteScalar();
54                 }
55             }
56         }  
57         #endregion
58         #region ExecuteDataTable
59         /// <summary>
60         /// ExecuteDataTable//查询获取相关字段的值
61         /// </summary>
62         /// <param name="sql">sql语句</param>
63         /// <param name="Parameters">参数/param>
64         /// <returns></returns>
65         public static DataTable ExecuteDataTable(string sql, params SqlParameter[] Parameters)
66         {
67             using (SqlConnection con = new SqlConnection(cons))
68             {
69                 con.Open();
70                 using (SqlCommand cmd = con.CreateCommand())
71                 {
72                     cmd.CommandText = sql;
73                     cmd.Parameters.AddRange(Parameters);
74                     DataTable table = new DataTable();
75                     SqlDataAdapter adapter = new SqlDataAdapter(cmd);
76                     adapter.Fill(table);
77                     return table;
78                 }
79             }
80         } 
81         #endregion
82     }
83 }

Model文件下的Person.cs 封装z字段相关，用于在三层之间数据的传递

View Code

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Linq;
 4 using System.Text;
 5 
 6 namespace 三层架构.Model
 7 {
 8     class Person
 9     {
10         public int Id { get; set; }
11         public string Name { get; set; }
12         public int Age { get; set; }
13     }
14 }

DAl下的PersonDAL.cs用于和数据库执行各种操作的SQL语句和方法

View Code

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Linq;
 4 using System.Text;
 5 using 三层架构.Model;
 6 using System.Data.SqlClient;
 7 using System.Data;
 8 
 9 namespace 三层架构.DAL
10 {
11     class PersonDAL
12     {
13         #region 新增
14         /// <summary>
15         /// 新增
16         /// </summary>
17         /// <param name="model">对象</param>
18         /// <returns></returns>
19         public int AddNew(Person model)//把要插入数据的模型传递给AddNew()
20         {
21             object obj = SQlHelper.ExecuteScalar("insert into  T_Person(Name,Age) values(@Name,@Age);select @@identity", new SqlParameter("Name", model.Name), new SqlParameter("Age", model.Age));//select @@identity执行插入后返回主键值
22             return Convert.ToInt32(obj);
23         } 
24         #endregion
25 
26         #region 删除
27         public int Delete(int id)
28         {
29             return SQlHelper.ExecuteNoQuery("delete from T_Person where Id=@Id", new SqlParameter("Id", id));
30         } 
31         #endregion
32         #region 更新
33         public int Update(Person model)
34         {
35             return SQlHelper.ExecuteNoQuery("update T_Person set Name=@Name, Age=@Age where Id=@Id", new SqlParameter("Id", model.Id), new SqlParameter("Name", model.Name), new SqlParameter("Age", model.Age));
36         } 
37         #endregion
38         #region 查询
39         public Person GetData(int id)
40         {
41             DataTable dt = SQlHelper.ExecuteDataTable("select * from T_Person where Id=@Id", new SqlParameter("Id", id));
42             if (dt.Rows.Count < 0)
43             {
44                 return null;
45             }
46             else if (dt.Rows.Count == 1)
47             {
48                 DataRow row = dt.Rows[0];
49                 Person model = new Person();
50                 model.Id = Convert.ToInt32(row["Id"]);
51                 model.Name = Convert.ToString(row["Name"]);
52                 model.Age = Convert.ToInt32(row["Age"]);
53                 return model;
54             }
55             else
56             {
57                 throw new Exception("数据出错，多条数据");
58             }
59         } 
60         #endregion
61         public IEnumerable<Person> GetAll()//IEnumerable<Person>使用该接口实现只读性
62         {
63             DataTable dt = SQlHelper.ExecuteDataTable("select * from T_Person");
64             List<Person> list = new List<Person>();
65             foreach (DataRow row in dt.Rows)
66             {
67                 Person model = new Person();
68                 model.Id = Convert.ToInt32(row["Id"]);
69                 model.Name= Convert.ToString(row["Name"]);
70                 model.Age = Convert.ToInt32(row["Age"]);
71                 list.Add(model);
72             }
73             return list;
74         }
75     }
76 }

BLL下的PersonBLL.cs用于执行和数据库交互前业务逻辑的判断处理

View Code

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Linq;
 4 using System.Text;
 5 using 三层架构.Model;
 6 using 三层架构.DAL;
 7 using System.Data.SqlClient;
 8 
 9 namespace 三层架构.BLL
10 {
11     class PersonBLL
12     {
13         #region 新增
14       
15         public int AddNew(Person model)//把要插入数据的模型传递给AddNew()
16         {
17             return new PersonDAL().AddNew(model);
18         }
19         #endregion
20 
21         #region 删除
22         public int Delete(int id)
23         {
24             return new PersonDAL().Delete(id);
25         }
26         #endregion
27         #region 更新
28         public int Update(Person model)
29         {
30             //BLL进行逻辑判断，DAL只进行数据库的操作！，这就是BLL和DAL的区别
31             if (model.Age <10)
32             {
33                 throw new Exception("年龄非法！！");
34             }
35             return new PersonDAL().Update(model);
36         }
37         #endregion
38         #region 查询
39         public Person GetData(int id)
40         {
41           return  new PersonDAL().GetData(id);
42         }
43         #endregion
44         public IEnumerable<Person> GetAll()//IEnumerable<Person>使用该接口实现只读性
45         {
46             return new PersonDAL().GetAll();
47         }
48     }
49 }

UI界面

采用三层架构用户界面变得相当简洁

View Code

 1 using System;
 2 using System.Collections.Generic;
 3 using System.ComponentModel;
 4 using System.Data;
 5 using System.Drawing;
 6 using System.Linq;
 7 using System.Text;
 8 using System.Windows.Forms;
 9 using 三层架构.Model;
10 using 三层架构.DAL;
11 using 三层架构.BLL;
12 
13 namespace 三层架构
14 {
15     public partial class Form1 : Form
16     {
17         public Form1()
18         {
19             InitializeComponent();
20         }
21 
22         private void button1_Click(object sender, EventArgs e)
23         {
24             Person p1 = new Person();
25             p1.Age = 20;
26             p1.Name = "小文";
27            int id= new PersonBLL().AddNew(p1);
28            MessageBox.Show(id.ToString());
29         }
30 
31         private void button2_Click(object sender, EventArgs e)
32         {
33             int Id = 3;
34             int count = new PersonBLL().Delete(Id);
35             MessageBox.Show("删除成功！！");
36         }
37 
38         private void button3_Click(object sender, EventArgs e)
39         {
40             Person p = new Person();
41             p.Id = 1;
42             p.Name = "想你";
43             p.Age = 21;
44             new PersonBLL().Update(p);
45             MessageBox.Show("更新成功！！");
46         }
47 
48         private void button4_Click(object sender, EventArgs e)
49         {
50             int id = 1;
51            Person p= new PersonBLL().GetData(id);
52            int Id = p.Id;
53            int Age = p.Age;
54            MessageBox.Show(Id.ToString());
55            MessageBox.Show(p.Name);
56            MessageBox.Show(Age.ToString());
57         }
58 
59         private void Form1_Load(object sender, EventArgs e)
60         {
61             dataGridView1.DataSource = new PersonBLL().GetAll();
62         }
63     }
64 }

<下篇博客主要是根据本篇的代码格式，完成自己的三层架构的代码生成器,居然现在市面上有很多的代码生成器，但有的时候还是更加喜欢自己的风格，今天写了一些，估计过几天就可以完成，到时候发到博客上，揭秘代码生成器的原理>

posted on 2012-04-19 19:57 aolinwxfx 阅读(712) 评论(0) 编辑收藏举报

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