A small instance of Java pseudo-interface operation database

First there are two tables fruit and login in MySQL:

 PackageCom.zuoye;ImportJava.sql.*;ImportJava.util.*; Public classTest { Public StaticString uid;  Public Static voidMain (string[] args)throwsexception{Scanner SC=NewScanner (system.in); System.out.println ("User name:"); UID=Sc.nextline (); System.out.println ("Password:"); String pwd=Sc.nextline (); Class.forName ("Com.mysql.jdbc.Driver"); Connection Conn= Drivermanager.getconnection ("Jdbc:mysql://127.0.0.1:3306/mydb?charactereconding=gbk", "Root", "" "); String SQL= "SELECT * from login where username=?" and password=? "; PreparedStatement P=conn.preparestatement (SQL); P.setstring (1, UID); P.setstring (2, PWD); ResultSet RS=P.executequery (); BooleanOK =Rs.next (); if(OK) {System.out.println ("Welcome:" +rs.getstring (2));                    Xuanxiang (); }        Else{System.out.println ("User name or password is incorrect");                } main (args);            Conn.close (); }     Public Static voidXuanxiang ()throwsexception{Scanner SC=NewScanner (system.in); System.out.println ("******* option *******"); System.out.println ("1. Show All Items"); System.out.println ("2. Add Item"); System.out.println ("3. Purchase Goods"); System.out.println ("4. Exit"); String a=Sc.nextline (); if(A.equals ("1") ) {Liebiao ();                                Xuanxiang (); }        Else if(A.equals ("2") ) {Tianjia ();        Xuanxiang (); }        Else if(A.equals ("3") ) {Goumai ();                    Xuanxiang (); }        Else{            return; }                            }         Public Static voidLiebiao ()throwsexception{Class.forName ("Com.mysql.jdbc.Driver"); Connection conn1= Drivermanager.getconnection ("Jdbc:mysql://127.0.0.1:3306/mydb?characterencoding=gbk", "Root", "" "); String SQL1= "SELECT * FROM Fruit"; Statement state1=conn1.createstatement (); ResultSet rs1=state1.executequery (SQL1);  while(Rs1.next ()) {System.out.print (rs1.getstring (1) + "\ T"); System.out.print (Rs1.getstring (2) + "\ T"); System.out.print (Rs1.getstring (3) + "\ T"); System.out.print (Rs1.getstring (4) + "\ T"); System.out.print (Rs1.getstring (5) + "\ T"); System.out.print (Rs1.getstring (6) + "\ n");    } conn1.close (); }     Public Static voidTianjia ()throwsexception{Scanner SC=NewScanner (system.in); System.out.println ("Please enter the number:"); String BH=Sc.nextline (); System.out.println ("Please enter the symbol:"); String PZ=Sc.nextline (); System.out.println ("Please enter the price:"); DoubleJG =double.parsedouble (Sc.nextline ()); System.out.println ("Please enter the origin:"); String CD=Sc.nextline (); System.out.println ("Please Enter quantity:"); intSl=Integer.parseint (Sc.nextline ()); System.out.println ("Please enter the image address:"); String DZ=Sc.nextline (); Class.forName ("Com.mysql.jdbc.Driver"); Connection Conn= Drivermanager.getconnection ("Jdbc:mysql://127.0.0.1:3306/mydb?charactereconding=gbk", "Root", "" "); String SQL= "INSERT into fruit values (?,?,?,?,?,?)"; PreparedStatement P=conn.preparestatement (SQL); P.setstring (1, BH); P.setstring (2, PZ); P.setdouble (3, JG); P.setstring (4, CD); P.setint (5, SL); P.setstring (6, DZ);                P.executeupdate ();    Conn.close (); }     Public Static voidGoumai ()throwsexception{Class.forName ("Com.mysql.jdbc.Driver"); Connection Conn= Drivermanager.getconnection ("Jdbc:mysql://127.0.0.1:3306/mydb?characterencoding=gbk", "Root", "" "); Scanner SC=NewScanner (system.in); System.out.println ("What Fruit to buy"); String PZ=Sc.nextline (); System.out.println ("How much to buy"); intGS =Integer.parseint (Sc.nextline ()); String SQL1= "SELECT * from fruit where name=?"; PreparedStatement P1=conn.preparestatement (SQL1); P1.setstring (1, PZ); ResultSet rs2=P1.executequery (); Doubles = 0;  while(Rs2.next ()) {s= (rs2.getdouble (3) *GS);        System.out.println (s); } String sql2= "Update fruit set Numbers = numbers-?" where Name =? "; PreparedStatement P2=conn.preparestatement (SQL2); P2.setint (1, GS); P2.setstring (2, PZ);                        P2.executeupdate (); String Sql3= "Update login Set account = account-?" where UserName =? "; PreparedStatement P3=conn.preparestatement (SQL3); P3.setdouble (1, s); P3.setstring (2, UID);                P3.executeupdate ();    Conn.close (); }}

User name: Lisi Password:666666welcome: John DoeOption *******1. Show All Products2. Add Item3. Purchase goods4. Exit1k001 Apples2.40 Yantai image/0. gifk002 Pineapple1.40 Guangdong IMAGE/1. gifk003 oranges2.40 Fuzhou IMAGE/2. gifk004 Grapes2.40 New Reins IMAGE/3. gifk005 Cherry2.40 Qingdao IMAGE/4. gifk006 Peach2.40 Huaguoshan IMAGE/5. gifk007 Banana2.40 Jinan IMAGE/6. gifOption *******1. Show All Products2. Add Item3. Purchase goods4. Exit

A small instance of Java pseudo-interface operation database