ContractProfessor.java Source code

Introduction

Here is the source code for ContractProfessor.java

Source

    File:ContractProfessor.java

    import javax.persistence.Column;
    import javax.persistence.Entity;

@Entity
public class ContractProfessor extends Professor {
    @Column(name="D_RATE")
    private int dailyRate;
    private int term;
    
    public int getDailyRate() {
        return dailyRate;
    }
    
    public void setDailyRate(int dailyRate) {
        this.dailyRate = dailyRate;
    }
    
    public int getTerm() {
        return term;
    }
    
    public void setTerm(int term) {
        this.term = term;
    }

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

    File:Professor.java

    import java.util.Date;

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

@Entity 
@Table(name="EMP")
@Inheritance
@DiscriminatorColumn(name="EMP_TYPE")
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: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();

    Professor emp = null;
    emp = new ContractProfessor();

    emp.setId(1);
    emp.setName("name");
    service.createProfessor(emp);

    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: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: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>