三層架構實例

一、新建立一個三層架構體系結構解決方案

新建一個空白解決方案。然后：????

1.“添加”－“新建項目”－“Visual C#”－“類庫”－“稱:LoginBLL”－“業務邏輯”（業務層，下簡稱B層）如下圖：

?2.“添加”－“新建項目”－“Visual C#”－“類庫”－“名稱:LoginDAL”－“數據訪問”（數據層，下簡稱D層）如下圖：

3.“添加”－“新建項目”－“Visual C#”－“類庫”－“名稱：LoginUI”（界面層，下簡稱U層）如下圖：

U層的界面效果圖：如下圖

?4. “添加”－“新建項目”－“Visual C#”－“類庫”－“名稱：LoginModel”（以下實體層）如下圖：

三層建立后的效果圖，如下圖：

二、引用（關鍵步驟）

右鍵點“解決方案”－“添加引用”，設置U依引用D、B，B引用于D。對U添加引用D、B，對B添加引用D。如下圖：

引用步驟一：

引用步驟二：

到此為止，一個登錄的三層架構的建立起來了。

三、各層實現代碼如下

B層代碼

[csharp] view plaincopyprint?

using?System;??

using?System.Collections.Generic;??

using?System.Linq;??

using?System.Text;??

using?System.Threading.Tasks;??

using?Login.BLL;??

using?Login.DAL;??

using?Login.Model;??

namespace?Login.BLL??

{??

????public?class?LoginManager??

????{??

????????public?UserInfo?UserLogin(string?userName,?string?password)??

????????{??

??

????????????UserDAO?uDao?=?new?UserDAO();??//實例化D層的類??

????????????UserInfo?user?=?uDao.SelectUser(userName,?password);?//將user信息傳遞給D層??

????????????if?(user?==?null)??//判斷user信息??

????????????{??

????????????????throw?new?Exception("登陸失敗");??

????????????}??

????????????else??

????????????{??

????????????????return?user;??

????????????}??

??

??

????????}??

????}??

}??

D層代碼

[csharp] view plaincopyprint?

using?System;??

using?System.Collections.Generic;??

using?System.Linq;??

using?System.Text;??

using?System.Threading.Tasks;??

using?Login.Model;??

using?System.Data.SqlClient;??

using?System.Data;??

??

namespace?Login.DAL??

{??

????public?class?UserDAO??

????{??

?????????//連接數據庫??

????????public?static?string?ConnString?=?@"Server=XJC-PC;?Database=chargeStudent;?User?ID=sa;?Password=123456";??

?????????

????????public??UserInfo?SelectUser(string?userName,?string?password)?//各層都要用到實體類userInfo?通過實體類連接??

??

????????{??

??????????????

????????????using?(SqlConnection?conn?=?new?SqlConnection(ConnString))??

????????????{??

????????????????SqlCommand?cmd?=?conn.CreateCommand();?//數據庫連接命令??

????????????????cmd.CommandText?=?@"select?*?from?user_Info?where?user_Name=@userName?AND?user_PWD=@password";??

????????????????cmd.CommandType?=?CommandType.Text;??

????????????????cmd.Parameters.Add(new?SqlParameter("@userName",?userName));??

????????????????cmd.Parameters.Add(new?SqlParameter("@password",?password));??

????????????????conn.Open();??

????????????????SqlDataReader?reader?=?cmd.ExecuteReader();??//讀取數據??

????????????????UserInfo?user?=?new?UserInfo();??

????????????????while?(reader.Read())??

????????????????{??

??????????????????????

????????????????????user.userName?=?reader.GetString(0);??

????????????????????user.password?=?reader.GetString(1);??

?????????????????????

????????????????}??

??????????????????return?user;??

????????????}??

????????????

????????}??

??

????}??

}??

U層代碼

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using?System;??

using?System.Collections.Generic;??

using?System.ComponentModel;??

using?System.Data;??

using?System.Drawing;??

using?System.Linq;??

using?System.Text;??

using?System.Threading.Tasks;??

using?System.Windows.Forms;??

using?System.Data.SqlClient;??

using?Login.BLL;??

using?Login.Model;??

namespace?LoginUI??

{??

????public?partial?class?Form1?:?Form??

????{??

????????public?Form1()??

????????{??

????????????InitializeComponent();??

????????}??

??

????????private?void?btnLogin_Click(object?sender,?EventArgs?e)??

????????{??

????????????LoginManager?mgr?=?new?LoginManager();?//實例化B層的類??

????????????string?userName?=?txtUserName.Text.Trim();??

????????????string?Password?=?txtPassword.Text;??

????????????UserInfo?user?=?mgr.UserLogin(userName,?Password);???//將user信息傳遞給B層????

????????????MessageBox.Show("登陸用戶："?+?userName);??

????????}??

????}??

}??

實體層代碼

[csharp] view plaincopyprint?

using?System;??

using?System.Collections.Generic;??

using?System.Linq;??

using?System.Text;??

using?System.Threading.Tasks;??

??

namespace?Login.Model??

{??

????public?class?UserInfo??

????{??

????????public?string?userName;??

????????public?string?UserName??

????????{??

????????????get?{?return?userName;?}??

????????????set?{?userName?=?value;?}??

????????}??

????????public?string?password;??

????????public?string?PassWord??

????????{??

????????????get?{?return?password;?}??

????????????set?{?password?=?value;?}??

????????}??

????}??

}??

四、運行成功的結果圖：如下圖

以上是我對“三層實例”的真是實現，如有不妥之處，還請指教。

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