Java Learning Note (53)-Classic three-tier architecture example

Userdao interface

/ * * Userdao interface * / Public InterfaceUserdao {//Insert User     Public void Insert(user user);//delete user     Public void Delete(intID);//Update users     Public void Update(user user);//Query All users     PublicList<user>getAllUsers();//Query users based on user name or password     PublicBooleanCheckUser(user user);//Query users by number     PublicUserGetuserbyid(intID);}

Userdaoimpl Implementation Class

ImportJava.sql.Connection;ImportJava.sql.PreparedStatement;ImportJava.sql.ResultSet;ImportJava.sql.SQLException;ImportJava.util.List;/ * * USERDAOIMPL Implementation class */ Public  class Userdaoimpl implements Userdao{Connection conn=NULL; PreparedStatement pstmt=NULL; ResultSet rs=NULL;@Override     Public void Insert(User user) {//TODO auto-generated method stub}@Override     Public void Delete(intID) {//TODO auto-generated method stub}@Override     Public void Update(User user) {//TODO auto-generated method stub}@Override     PublicList<user>getAllUsers() {//TODO auto-generated method stub        return NULL; }@Override     Public Boolean CheckUser(User user) {Booleanflag=false; String sql="SELECT * from user where username=?" and password=? ";Try{conn=dbutil.getconnection ();            Pstmt=conn.preparestatement (SQL); Pstmt.setstring (1, User.getusername ()); Pstmt.setstring (2, User.getpassword ()); Rs=pstmt.executequery ();if(Rs.next ()) {flag=true; }        }Catch(SQLException e)        {E.printstacktrace (); }finally{Dbutil.closeall (RS, PSTMT, conn); }returnFlag }@Override     PublicUserGetuserbyid(intID) {//TODO auto-generated method stub        return NULL; }}

UserService interface

/* * UserService接口 */publicinterface UserService {    //用户注册    publicvoidregister(User user);    //用户登陆    publiclogin(User user);}

Userserviceimpl implementation class, invoking DAO to complete the corresponding function

/* * Userserviceimpl implementation class, Call DAO to complete the corresponding function */ public   class  userserviceimpl  implements  userservice  { //Create Userdao instance  Userdao ud=new     Userdaoimpl ();     @Override  public  void  register  (User user)    {Ud.insert (user); }  @Override  public  boolean  login  (User user) {return<    /span> ud.checkuser (user); }}

Database Tools Classes

ImportJava.sql.Connection;ImportJava.sql.DriverManager;ImportJava.sql.ResultSet;ImportJava.sql.SQLException;ImportJava.sql.Statement;/ * Database Tools class */ Public  class dbutil {    //Get database connection     Public StaticConnectiongetconnection() {Connection conn=NULL;Try{Class.forName ("Com.mysql.jdbc.Driver"); Conn=drivermanager.getconnection ("Jdbc:mysql://localhost:3306/test","Root","123456"); }Catch(ClassNotFoundException e)        {E.printstacktrace (); }Catch(SQLException e)        {E.printstacktrace (); }returnConn }//Close all resources     Public Static void CloseAll(ResultSet rs,statement stmt,connection conn) {Try{if(rs!=NULL) Rs.close ();if(stmt!=NULL) Stmt.close ();if(conn!=NULL) Conn.close (); }Catch(SQLException e)        {E.printstacktrace (); }    }}

Login Form

/ * * Login Form */ Public  class Login implements ActionListener {    //Define a UserService instanceUserService us=NewUserserviceimpl ();//Login Form Components    PrivateJFrame Frmlogin =NewJFrame ("Login");Privatejpanel[] Pnls =Newjpanel[4];//4 row panel    PrivateJLabel Lblwelcome =NewJLabel ("Welcome to the small supermarket management system!" ");PrivateJLabel Lblusername =NewJLabel ("User name:");PrivateJTextField txtUserName =NewJTextField ( -);PrivateJLabel Lblpassword =NewJLabel ("Password:");PrivateJPasswordField Txtpassword =NewJPasswordField ( -);PrivateJButton Btnlogin =NewJButton ("Login");PrivateJButton Btnexit =NewJButton ("Exit");//Initialize Components     Public Login() {//Initialize 4 rows panel and add to form         for(inti =0; i < pnls.length; i++) {Pnls[i] =NewJPanel (); Pnls[i].setopaque (false);//Set panel transparentFrmlogin.add (Pnls[i]);//Add a panel to the Assembly}//Initialize the JLabel and text boxes, and add the load panelLblwelcome.setfont (NewFont ("Blackbody", Font.Bold, -));        Lblwelcome.setforeground (color.red); pnls[0].add (Lblwelcome); pnls[1].setlayout (NewFlowLayout (Flowlayout.center, -,0)); pnls[1].add (Lblusername); pnls[1].add (txtUserName); pnls[2].setlayout (NewFlowLayout (Flowlayout.center, -,0)); pnls[2].add (Lblpassword); pnls[2].add (Txtpassword); pnls[3].setlayout (NewFlowLayout (Flowlayout.center, -,0)); pnls[3].add (Btnlogin); pnls[3].add (Btnexit);//Add monitoringBtnlogin.addactionlistener ( This); Btnexit.addactionlistener ( This);//Set the form background pictureImageIcon iconbg=NewImageIcon ("Images/bg.jpg"); JLabel lblbg=NewJLabel (ICONBG);        Lblbg.setsize (Iconbg.geticonwidth (), Iconbg.geticonheight ());        JLayeredPane Layeredpane=frmlogin.getlayeredpane (); Layeredpane.add (LBLBG,NewInteger (Integer.min_value));        JPanel contentpane= (JPanel) Frmlogin.getcontentpane (); Contentpane.setopaque (false);//Initialize formFrmlogin.setlayout (NewGridLayout (4,1)); Frmlogin.setsize ( -, -); Frmlogin.setresizable (false); Frmlogin.setlocationrelativeto (NULL);        Frmlogin.setdefaultcloseoperation (Jframe.exit_on_close); Frmlogin.setvisible (true); }@Override     Public void actionperformed(ActionEvent e) {String cmd = E.getactioncommand ();//Get text on the button        if(Cmd.equals ("Login") {String username=txtusername.gettext (); String password=NewString (Txtpassword.getpassword ()); User user=NewUser (Username,password);if(Us.login (user)) {Frmlogin.dispose ();//Hide Login Form                NewJFrame (). setvisible (true); }Else{Joptionpane.showmessagedialog (Frmlogin,"The user name or password is incorrect!" "); }        }Else{intChoice=joptionpane.showconfirmdialog (Frmlogin,"Are you sure you want to quit?" ","Hint", Joptionpane.yes_no_option, Joptionpane.question_message);if(choice==0){//If you select Yes, exit the programSystem.exit (0); }        }    } Public Static void Main(string[] args) {NewLogin (); }}

Database design

 Create table user(id int primary key auto_increment, user Name varchar() not  null, password varchar   null); Insert  into user values (null,' admin ',' 123 '); insert into  user values (null,' Tom ',' 456 ' );

Java Learning Note (53)-Classic three-tier architecture example