Java by API/javax.persistence/DiscriminatorType

DiscriminatorType.INTEGER

   <source lang="java">
 

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().rumit();
   em.close();
   emf.close();
 }

}

File: persistence.xml <persistence xmlns="http://java.sun.ru/xml/ns/persistence"

            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
            xsi:schemaLocation="http://java.sun.ru/xml/ns/persistence http://java.sun.ru/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>

 </source>