DAO interface and Implementation class

All user actions are defined in the DAO interface, such as adding records, deleting records, and querying records.

1  PackageChapter13;2 ImportJava.util.*;3  Public InterfaceUserdao {4      Public voidInsert (user user)throwsException;5      Public voidUpdate (user user)throwsException;6      Public voidDeleteintUserIDthrowsException;7      PublicUser Querybyid (intUserIDthrowsException;8      PublicList<user> Queryall ()throwsException;9}

The DAO implementation class implements the DAO interface and implements all the methods defined in the interface.

1  PackageChapter13;2 3 ImportJava.util.*;4 ImportJava.sql.*;5 Importjava.sql.Date;6 7  Public classUserdaoimplImplementsUserdao {8 9 @OverrideTen      Public voidInsert (user user)throwsException { One         //TODO auto-generated Method Stub AString sql= "INSERT into User (Username,password) VALUES (?,?)"; -PreparedStatement preparedstatement=NULL; -DatabaseConnection dbc=NULL; the         Try{ -Dbc=Newdatabaseconnection (); -Preparedstatement=dbc.getconnection (). preparestatement (SQL); -Preparedstatement.setstring (1, User.getusername ()); +Preparedstatement.setstring (2, User.getpassword ()); - preparedstatement.executeupdate (); + preparedstatement.close (); A         } at         Catch(Exception e) { -             Throw NewException ("Operation Exception"); -}finally { - dbc.close (); -         } -  in     } -  to @Override +      Public voidUpdate (user user)throwsException { -         //TODO auto-generated Method Stub theString sql= "Update user set username=?,password=?" where userid=? "; *PreparedStatement preparedstatement=NULL; $DatabaseConnection dbc=NULL;Panax Notoginseng         Try{ -Dbc=Newdatabaseconnection (); thePreparedstatement=dbc.getconnection (). preparestatement (SQL); +Preparedstatement.setstring (1, User.getusername ()); APreparedstatement.setstring (2, User.getpassword ()); thePreparedstatement.setint (3, User.getuserid ()); + preparedstatement.executeupdate (); - preparedstatement.close (); $         } $         Catch(Exception e) { -             Throw NewException ("Operation Exception"); -}finally { the dbc.close (); -         }Wuyi     } the  - @Override Wu      Public voidDeleteintUserIDthrowsException { -         //TODO auto-generated Method Stub AboutString sql= "Delete from user where userid=?"; $PreparedStatement preparedstatement=NULL; -DatabaseConnection dbc=NULL; -         Try{ -Dbc=Newdatabaseconnection (); APreparedstatement=dbc.getconnection (). preparestatement (SQL); +Preparedstatement.setint (1, userid); the preparedstatement.executeupdate (); - preparedstatement.close (); $         } the         Catch(Exception e) { the             Throw NewException ("Operation Exception"); the}finally { the dbc.close (); -         } in     } the  the @Override About      PublicUser Querybyid (intUserIDthrowsException { the         //TODO auto-generated Method Stub theUser user=NULL; theString sql= "SELECT * from user where userid=?"; +PreparedStatement preparedstatement=NULL; -DatabaseConnection databaseconnection=NULL; the         Try{Bayidatabaseconnection=Newdatabaseconnection (); thePreparedstatement=databaseconnection.getconnection (). preparestatement (SQL); theResultSet rset=preparedstatement.executequery (); -             if(Rset.next ()) { -User=NewUser (); theUser.setuserid (Rset.getint (1)); theUser.setusername (Rset.getstring (2)); theUser.setpassword (Rset.getstring (3)); the             } - rset.close (); the preparedstatement.close (); the         } the         Catch(Exception e) {94             Throw NewException ("Operation Exception"); the}finally { the databaseconnection.close (); the         }98         returnuser; About     } - 101 @Override102      PublicList<user> Queryall ()throwsException {103         //TODO auto-generated Method Stub104List<user> all=NewArraylist<user>(); theString sql= "SELECT * from User";106PreparedStatement preparedstatement=NULL;107DatabaseConnection databaseconnection=NULL;108         Try{109databaseconnection=Newdatabaseconnection (); thePreparedstatement=databaseconnection.getconnection (). preparestatement (SQL);111ResultSet rset=preparedstatement.executequery (); the             if(Rset.next ()) {113User user=NewUser (); theUser=NewUser (); theUser.setuserid (Rset.getint (1)); theUser.setusername (Rset.getstring (2));117User.setpassword (Rset.getstring (3));118 all.add (user);119             } - rset.close ();121 preparedstatement.close ();122         }123         Catch(Exception e) {124             Throw NewException ("Operation Exception"); the}finally {126 databaseconnection.close ();127         } -         returnAll ;129     } the 131}

DAO interface and Implementation class