AbstractProfessor.java Source code

Introduction

Here is the source code for AbstractProfessor.java

Source

    File:AbstractProfessor.java

    import javax.persistence.MappedSuperclass;

@MappedSuperclass
public abstract class AbstractProfessor extends Professor {
    private int vacation;

    public int getVacation() {
        return vacation;
    }

    public void setVacation(int vacation) {
        this.vacation = vacation;
    }
}

    File:BadProfessor.java

    import javax.persistence.Column;
    import javax.persistence.DiscriminatorValue;
    import javax.persistence.Entity;
    import javax.persistence.Table;

@Entity
@Table(name="Bad_EMP")
@DiscriminatorValue("3")
public class BadProfessor extends AbstractProfessor {
    @Column(name="H_RATE")
    private float hourlyRate = 1;

    public float getHourlyRate() {
        return hourlyRate;
    }

    public void setHourlyRate(float hourlyRate) {
        this.hourlyRate = hourlyRate;
    }

    public String toString() {
        return "PartTimeProfessor id: " + getId() + " name: " + getName();
    }
}

    File:GoodProfessor.java

    import javax.persistence.DiscriminatorValue;
    import javax.persistence.Entity;
    import javax.persistence.Table;

@Entity
@Table(name="Good_EMP")
@DiscriminatorValue("2")
public class GoodProfessor extends AbstractProfessor {
    private long salary = 1;
    private long pension = 1;
    
    public long getPension() {
        return pension;
    }
    
    public void setPension(long pension) {
        this.pension = pension;
    }
    
    public long getSalary() {
        return salary;
    }
    
    public void setSalary(long salary) {
        this.salary = salary;
    }

    public String toString() {
        return "FullTimeProfessor id: " + getId() + " name: " + getName();
    }
}

    File:Professor.java

    import java.util.Date;

    import javax.persistence.Column;
    import javax.persistence.DiscriminatorColumn;
    import javax.persistence.DiscriminatorType;
    import javax.persistence.Entity;
    import javax.persistence.Id;
    import javax.persistence.Inheritance;
    import javax.persistence.InheritanceType;
    import javax.persistence.Table;
    import javax.persistence.Temporal;
    import javax.persistence.TemporalType;

@Entity
@Table(name = "EMP")
@Inheritance(strategy = InheritanceType.JOINED)
@DiscriminatorColumn(name = "EMP_TYPE", discriminatorType = DiscriminatorType.INTEGER)
public abstract class Professor {
  @Id
  private int id;

  private String name;

  @Temporal(TemporalType.DATE)
  @Column(name = "S_DATE")
  private Date startDate;

  public int getId() {
    return id;
  }

  public void setId(int id) {
    this.id = id;
  }

  public String getName() {
    return name;
  }

  public void setName(String name) {
    this.name = name;
  }

  public Date getStartDate() {
    return startDate;
  }

  public void setStartDate(Date startDate) {
    this.startDate = startDate;
  }

  public String toString() {
    return "Professor id: " + getId() + " name: " + getName();
  }
}

    File:ProfessorService.java

    import java.util.Collection;

    import javax.persistence.EntityManager;
    import javax.persistence.Query;

public class ProfessorService {
  protected EntityManager em;

  public ProfessorService(EntityManager em) {
    this.em = em;
  }

  public void createProfessor(Professor emp) {
    em.persist(emp);
  }

  public Collection<Professor> findAllProfessors() {
    Query query = em.createQuery("SELECT e FROM Professor e");
    return (Collection<Professor>) query.getResultList();
  }
}

    File:JPAUtil.java

    import java.io.Reader;
    import java.sql.Connection;
    import java.sql.DriverManager;
    import java.sql.ResultSet;
    import java.sql.ResultSetMetaData;
    import java.sql.Statement;

public class JPAUtil {
  Statement st;
  
  public JPAUtil() throws Exception{
    Class.forName("org.hsqldb.jdbcDriver");
    System.out.println("Driver Loaded.");
    String url = "jdbc:hsqldb:data/tutorial";

    Connection conn = DriverManager.getConnection(url, "sa", "");
    System.out.println("Got Connection.");
    st = conn.createStatement();
  }
  public void executeSQLCommand(String sql) throws Exception {
    st.executeUpdate(sql);
  }
  public void checkData(String sql) throws Exception {
    ResultSet rs = st.executeQuery(sql);
    ResultSetMetaData metadata = rs.getMetaData();

    for (int i = 0; i < metadata.getColumnCount(); i++) {
      System.out.print("\t"+ metadata.getColumnLabel(i + 1)); 
    }
    System.out.println("\n----------------------------------");

    while (rs.next()) {
      for (int i = 0; i < metadata.getColumnCount(); i++) {
        Object value = rs.getObject(i + 1);
        if (value == null) {
          System.out.print("\t       ");
        } else {
          System.out.print("\t"+value.toString().trim());
        }
      }
      System.out.println("");
    }
  }
}

    File:Main.java

    import javax.persistence.EntityManager;
    import javax.persistence.EntityManagerFactory;
    import javax.persistence.Persistence;

    public class Main {
        public static void main(String[] a) throws Exception {
            JPAUtil util = new JPAUtil();

            EntityManagerFactory emf = Persistence.createEntityManagerFactory("ProfessorService");
            EntityManager em = emf.createEntityManager();
            ProfessorService service = new ProfessorService(em);

            em.getTransaction().begin();

            GoodProfessor emp = null;
            emp = new GoodProfessor();
            emp.setId(1);
            emp.setName("good");

            service.createProfessor(emp);

            BadProfessor emp2 = new BadProfessor();
            emp2.setId(2);

            emp2.setName("bad");

            service.createProfessor(emp2);

            System.out.println("Professors: ");
            for (Professor emp1 : service.findAllProfessors()) {
                System.out.print(emp1);
            }

            util.checkData("select * from EMP");

            em.getTransaction().commit();
            em.close();
            emf.close();
        }
    }

    File:persistence.xml

    <persistence xmlns="http://java.sun.com/xml/ns/persistence"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence"version="1.0"><persistence-unit name="JPAService"transaction-type="RESOURCE_LOCAL"><properties><property name="hibernate.dialect"value="org.hibernate.dialect.HSQLDialect"/><property name="hibernate.hbm2ddl.auto"value="update"/><property name="hibernate.connection.driver_class"value="org.hsqldb.jdbcDriver"/><property name="hibernate.connection.username"value="sa"/><property name="hibernate.connection.password"value=""/><property name="hibernate.connection.url"value="jdbc:hsqldb:data/tutorial"/></properties></persistence-unit></persistence>