package persistence.db;

import business_logic.Address;
import business_logic.EMail;
import business_logic.MainInterface;
import business_logic.Telephone;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.logging.Level;
import java.util.logging.Logger;

public abstract class DAO<T extends MainInterface>{
    private Connection connection;

    public DAO(Connection connection){
        this.connection = connection;
    }

    public Connection getConnection(){
        return connection;
    }

    public void closeAll(ResultSet rs, PreparedStatement pstmt){
        try{
            if(pstmt != null)
                pstmt.close();
            if(rs != null)
                rs.close();
        }catch(SQLException sqle){}
    }

    public long getModified(String table, int id){
        PreparedStatement pstmt = null;
        ResultSet rs = null;
        try{
            pstmt = connection.prepareStatement("SELECT modified FROM "+table+" WHERE id = ?");
            pstmt.setInt(1, id);
            rs = pstmt.executeQuery();
            if(rs.next())
                return rs.getLong("modified");
            else
                return 0;
        }catch(SQLException ex){
            Logger.getLogger(DAO.class.getName()).log(Level.SEVERE, null, ex);
        }finally{
            closeAll(rs, pstmt);
        }
        return 0;
    }

    public long getCurrentTimestamp(){
        return System.currentTimeMillis()/1000;
    }

    public void setId(PreparedStatement pstmt, T a){
        try{
            ResultSet keys = pstmt.getGeneratedKeys();
            if (keys.next())
                a.setId(keys.getInt(1));
            keys.close();
        }catch(SQLException ex){
            Logger.getLogger(DAO.class.getName()).log(Level.SEVERE, null, ex);
        }
    }
}

package test;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.logging.Level;
import java.util.logging.Logger;
import persistence.db.*;
import business_logic.*;


public class AddressDaoTest{
    private static Connection connection;
    private static AddressDAO dao;

    public static void main(String args[]){
        try{
            Class.forName("com.mysql.jdbc.Driver");
        }catch(ClassNotFoundException ex){
            Logger.getLogger(MySQL.class.getName()).log(Level.SEVERE, null, ex);
        }
        try{
            connection = DriverManager.getConnection("jdbc:mysql://localhost/schoolmanagement", "root", "");
        }catch(SQLException ex){
            Logger.getLogger(MySQL.class.getName()).log(Level.SEVERE, null, ex);
        }
        dao = new AddressDAO(connection);
        Address ad = null;
        try{
            ad = new Address(0, 1, 0, 0, "Teststreet", "Testhnr", "1234", "Testcity");
        }catch(SchulException ex){
            Logger.getLogger(AddressDaoTest.class.getName()).log(Level.SEVERE, null, ex);
        }
        System.out.println("ID: "+ad.getId());///getId liefert 0, da dem Konstruktor 0 übergeben wird
        dao.save(ad);
        System.out.println("ID: "+ad.getId());//getId liefert immer noch 0
    }
}