Java by API/javax.persistence/GenerationType

GenerationType.AUTO

   <source lang="java">
 

File: Professor.java import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id;

@Entity public class Professor {

 @Id
 @GeneratedValue(strategy=GenerationType.AUTO)
 private int id;
 private String name;
 private long salary;

 public Professor() {
 }
 public Professor(int id) {
   this.id = id;
 }
 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 long getSalary() {
   return salary;
 }
 public void setSalary(long salary) {
   this.salary = salary;
 }

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

}

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 Professor createProfessor(String name, long salary) {
   Professor emp = new Professor();
   emp.setName(name);
   emp.setSalary(salary);
   em.persist(emp);
   
   return emp;
 }
 public void removeProfessor(int id) {
   Professor emp = findProfessor(id);
   if (emp != null) {
     em.remove(emp);
   }
 }
 public Professor raiseProfessorSalary(int id, long raise) {
   Professor emp = em.find(Professor.class, id);
   if (emp != null) {
     emp.setSalary(emp.getSalary() + raise);
   }
   return emp;
 }
 public Professor findProfessor(int id) {
   return em.find(Professor.class, id);
 }
 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 = service.createProfessor("AAA", 45000);
   em.getTransaction().rumit();
   System.out.println("Persisted " + emp);
   util.checkData("select * from Professor");
   
   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.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>
   
  
 
  

GenerationType.IDENTITY

   <source lang="java">
 

File: Professor.java

import java.util.ArrayList; import java.util.Collection; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; import javax.persistence.JoinColumn; import javax.persistence.JoinTable; import javax.persistence.ManyToMany; @Entity public class Professor {

   @Id @GeneratedValue(strategy=GenerationType.IDENTITY)
   private int id;
   private String name;
   private long salary;
   
   @ManyToMany 
   @JoinTable(name="EMP_PROJ", 
         joinColumns=@JoinColumn(name="EMP_ID"),
         inverseJoinColumns=@JoinColumn(name="PROJ_ID"))
   private Collection<Project> projects;
   
   
   public Professor() {
       projects = new ArrayList<Project>();
   }
   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 long getSalary() {
       return salary;
   }
   public void setSalary(long salary) {
       this.salary = salary;
   }
   
   public void addProject(Project project) {
       if (!getProjects().contains(project)) {
           getProjects().add(project);
       }
       if (!project.getProfessors().contains(this)) {
           project.getProfessors().add(this);
       }
   }
   public Collection<Project> getProjects() {
       return projects;
   }
   public String toString() {
       return "Professor id: " + getId() + " name: " + getName() + 
              " with " + getProjects().size() + " projects";
   }

}

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 Project createProject(String name) {
   Project proj = new Project();
   proj.setName(name);
   em.persist(proj);
   return proj;
 }
 public Collection<Project> findAllProjects() {
   Query query = em.createQuery("SELECT p FROM Project p");
   return (Collection<Project>) query.getResultList();
 }
 public Professor createProfessor(String name, long salary) {
   Professor emp = new Professor();
   emp.setName(name);
   emp.setSalary(salary);
   em.persist(emp);
   return emp;
 }
 public Professor addProfessorProject(int empId, int projId) {
   Professor emp = em.find(Professor.class, empId);
   Project proj = em.find(Project.class, projId);
   proj.addProfessor(emp);
   return emp;
 }
 public Collection<Professor> findAllProfessors() {
   Query query = em.createQuery("SELECT e FROM Professor e");
   return (Collection<Professor>) query.getResultList();
 }

}

File: Project.java

import java.util.ArrayList; import java.util.Collection; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; import javax.persistence.ManyToMany; @Entity public class Project {

   @Id @GeneratedValue(strategy=GenerationType.IDENTITY)
   protected int id;
   protected String name;
   @ManyToMany(mappedBy="projects")
   private Collection<Professor> employees;
   public Project() {
       employees = new ArrayList<Professor>();
   }
   public int getId() {
       return id;
   }
   
   public void setId(int projectNo) {
       this.id = projectNo;
   }
   
   public String getName() {
       return name;
   }
   
   public void setName(String projectName) {
       this.name = projectName;
   }
   
   public Collection<Professor> getProfessors() {
       return employees;
   }
   
   public void addProfessor(Professor employee) {
       if (!getProfessors().contains(employee)) {
           getProfessors().add(employee);
       }
       if (!employee.getProjects().contains(this)) {
           employee.getProjects().add(this);
       }
   }
   
   public String toString() {
       return "Project id: " + getId() + ", name: " + getName() +
              " with " + getProfessors().size() + " employees";
   }

}

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 java.util.Collection; 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 = service.createProfessor("empName",100);
   Project proj = service.createProject("projName");

   emp = service.addProfessorProject(emp.getId(),proj.getId());
   Collection<Professor> emps = service.findAllProfessors();
   if (emps.isEmpty()) {
       System.out.println("No Professors found ");
   } else {
     System.out.println("Found Professors:");
       for (Professor emp1 : emps) {
         System.out.println(emp1);
       }
   }
   
   Collection<Project> projs = service.findAllProjects();
   if (projs.isEmpty()) {
     System.out.println("No Projects found ");
   } else {
     System.out.println("Found Projects:");
       for (Project proj1 : projs) {
         System.out.println(proj1);
       }
   }
   util.checkData("select * from Professor");
   
   util.checkData("select * from Project");
   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>
   
  
 
  

GenerationType.TABLE

   <source lang="java">
 

File: Address.java import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; import javax.persistence.TableGenerator; @Entity public class Address {

 @TableGenerator(name = "Address_Gen", table = "ID_GEN", pkColumnName = "GEN_NAME", valueColumnName = "GEN_VAL", pkColumnValue = "Addr_Gen", initialValue = 10000, allocationSize = 100)
 @Id
 @GeneratedValue(strategy = GenerationType.TABLE, generator = "Address_Gen")
 private int id;
 private String street;
 private String city;
 private String state;
 private String zip;
 public int getId() {
   return id;
 }
 public void setId(int id) {
   this.id = id;
 }
 public String getStreet() {
   return street;
 }
 public void setStreet(String address) {
   this.street = address;
 }
 public String getCity() {
   return city;
 }
 public void setCity(String city) {
   this.city = city;
 }
 public String getState() {
   return state;
 }
 public void setState(String state) {
   this.state = state;
 }
 public String getZip() {
   return zip;
 }
 public void setZip(String zip) {
   this.zip = zip;
 }
 public String toString() {
   return "Address id: " + getId() + ", street: " + getStreet() + ", city: " + getCity()
       + ", state: " + getState() + ", zip: " + getZip();
 }

}

File: Professor.java import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; import javax.persistence.OneToOne; import javax.persistence.TableGenerator; @Entity public class Professor {

 @TableGenerator(name = "Emp_Gen", table = "ID_GEN", pkColumnName = "GEN_NAME", valueColumnName = "GEN_VAL")
 @Id
 @GeneratedValue(strategy = GenerationType.TABLE, generator = "Emp_Gen")
 private int id;
 private String name;
 private long salary;
 @OneToOne
 private Address address;
 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 long getSalary() {
   return salary;
 }
 public void setSalary(long salary) {
   this.salary = salary;
 }
 public Address getAddress() {
   return address;
 }
 public void setAddress(Address address) {
   this.address = address;
 }
 public String toString() {
   return "Professor id: " + getId() + " name: " + getName() + " salary: " + getSalary();
 }

}

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 Professor createProfessor(String name, long salary, 
         String street, String city, String state, String zip) {
     Professor emp = new Professor();
     emp.setName(name);
     emp.setSalary(salary);
     
     Address addr = new Address();
     addr.setStreet(street);
     addr.setCity(city);
     addr.setState(state);
     addr.setZip(zip);
     emp.setAddress(addr);
     em.persist(emp);
     em.persist(addr);
     
     return emp;
 }
 public void removeProfessor(int id) {
   Professor emp = findProfessor(id);
   if (emp != null) {
     em.remove(emp);
   }
 }
 public Professor raiseProfessorSalary(int id, long raise) {
   Professor emp = em.find(Professor.class, id);
   if (emp != null) {
     emp.setSalary(emp.getSalary() + raise);
   }
   return emp;
 }
 public Professor findProfessor(int id) {
   return em.find(Professor.class, id);
 }
 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 = service.createProfessor("name", 100, 
       "street", "city", "state", "zip");
   em.getTransaction().rumit();
   System.out.println("Persisted " + emp);
   util.checkData("select * from Professor");
   util.checkData("select * from ADDRESS");
   util.checkData("select * from ID_GEN");
   
   
   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.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>