Three-tier implementation of user login C #

in the previous article, we talked about layer three. The next step is to use a detailed example of how to implement user login interface with three layers.

Model Entity (Loginmodel):

namespace loginmodel{     //Join class: UserInfo  model entity action: Encapsulates the data so that the data is transferred in layer three. More inclined to business logic Layer public    class UserInfo    {        //define user Properties public        int ID {get; set;}        public string UserName {get; set;}        public string Password {get; set;}}            }

second, the design of the UI layer:

The first simple interface believes that everyone will:

Next is the code:

namespace loginui{public    partial class Frmlogin:form    {public        frmlogin ()        {            InitializeComponent ();        }        private void Btnlogin_click (object sender, EventArgs e)        {            //ui layer passes user input data to the BLL layer            string userName = TxtUserName.Text.Trim ();            string password = txtPassword.Text;            Loginbll.loginmanager mgr = new Loginbll.loginmanager ();            Loginmodel.userinfo user = Mgr. Userlogin (userName, password);            Returns the UI layer to the user            MessageBox.Show ("Logged in User:" + user) for the data passed by the business layer. UserName);}}}           

Three, the BLL layer code

namespace loginbll{public    class Loginmanager    {public        loginmodel.userinfo userlogin (String userName, String password)        {            Logindal.userdao Udao = new Logindal.userdao ();//Instantiate DAL layer            loginmodel.userinfo user = Udao.selectuser (userName, password);            No need to access the data source to run the business logic directly            if (user! = null)            {                return user;            }            else            {                throw new Exception ("Login Failed");                            }        }    }

Four, the DAL layer code

 public class Userdao {public Loginmodel.userinfo selectuser (string userName, String Password) { Establish database connection string connstring = @ "server=192.168.24.154;database= computer room charge system personnel records; User Id=sa;            Password=123 "; using (SqlConnection conn = new SqlConnection (connstring)) {//Run SQL statement for query sqlcom Mand cmd = conn.                CreateCommand (); Cmd.                CommandText = @ "Select Id,username,password from UserInfo WHERE [email protected] and [email protected]"; Output query result cmd.                CommandType = CommandType.Text; Add two number of parameters to CMD.                Parameters.Add (New SqlParameter (@ "UserName", UserName)); Cmd.                Parameters.Add (New SqlParameter (@ "Password", Password)); Conn.                Open (); SqlDataReader reader = cmd.                ExecuteReader ();                Loginmodel.userinfo user = null; Read the detailed data while (reader. Read ())               {if (user = = null) {user = new loginmodel.us                    Erinfo (); }//Read the query to the data User.ID = reader.                    GetInt32 (0); User. UserName = reader.                    GetString (1); User. Password = reader.                                   GetString (2);            } return user; }        }    }}

Login:

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Three-tier implementation of user login C #