Java/JPA/Primary Key
Содержание
- 1 Define And Use Compound Primary Key
- 2 JPA can Create Sequence Table For You
- 3 Mark Entity ID As Generated Value From Table
- 4 Not Nullable ID
- 5 Relationship On Id
- 6 Sequence Id Generation
- 7 Set IdClass for Compound Key
- 8 Set Primary Key By Yourself
- 9 Set Primary Key Joined Column For Secondary Table
- 10 Use UUID As Primary Key
- 11 Using Primary Key Column as Joined Column
- 12 Using System MilliSeconds As Key
Define And Use Compound Primary Key
<source lang="java">
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(); service.createProfessor("country", 1, "name", 100); Professor emp = service.findProfessor("country", 1); System.out.println("Found " + emp); System.out.println("Professors:"); for (Professor emp1 : service.findAllProfessors()) { System.out.print(emp1); } util.checkData("select * from Professor"); em.getTransaction().rumit(); 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: Professor.java
import javax.persistence.Column; import javax.persistence.Entity; import javax.persistence.Id; import javax.persistence.IdClass; @Entity @IdClass(ProfessorId.class) public class Professor {
@Id private String country; @Id @Column(name="EMP_ID") private int id; private String name; private long salary; public int getId() { return id; } public void setId(int id) { this.id = id; } public String getCountry() { return country; } public void setCountry(String country) { this.country = country; } 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() + " country: " + getCountry(); }
}
File: ProfessorId.java import java.io.Serializable; public class ProfessorId implements Serializable {
private String country; private int id; public ProfessorId() { } public ProfessorId(String country, int id) { this.country = country; this.id = id; } public String getCountry() { return country; } public int getId() { return id; } public boolean equals(Object o) { return ((o instanceof ProfessorId) && country.equals(((ProfessorId) o).getCountry()) && id == ((ProfessorId) o) .getId()); } public int hashCode() { return country.hashCode() + id; }
}
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 country, int id, String name, long salary) { Professor emp = new Professor(); emp.setCountry(country); emp.setId(id); emp.setName(name); emp.setSalary(salary); em.persist(emp); return emp; } public Professor findProfessor(String country, int id) { return em.find(Professor.class, new ProfessorId(country, id)); } public Collection<Professor> findAllProfessors() { Query query = em.createQuery("SELECT e FROM Professor e"); return (Collection<Professor>) query.getResultList(); }
}
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>
JPA can Create Sequence Table For You
<source lang="java">
File: Student.java import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; @Entity public class Student {
@Id @GeneratedValue(strategy=GenerationType.TABLE) private int id; transient private String name;
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 String toString() { return "\n\nID:" + id + "\nName:" + name + "\n\n"; }
}
File: Helper.java import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.ResultSetMetaData; import java.sql.Statement; public class Helper {
public static void checkData() throws Exception { Class.forName("org.hsqldb.jdbcDriver"); Connection conn = DriverManager.getConnection("jdbc:hsqldb:data/tutorial", "sa", ""); Statement st = conn.createStatement(); ResultSet mrs = conn.getMetaData().getTables(null, null, null, new String[] { "TABLE" }); while (mrs.next()) { String tableName = mrs.getString(3); System.out.println("\n\n\n\nTable Name: "+ tableName); ResultSet rs = st.executeQuery("select * from " + tableName); ResultSetMetaData metadata = rs.getMetaData(); while (rs.next()) { System.out.println(" Row:"); for (int i = 0; i < metadata.getColumnCount(); i++) { System.out.println(" Column Name: "+ metadata.getColumnLabel(i + 1)+ ", "); System.out.println(" Column Type: "+ metadata.getColumnTypeName(i + 1)+ ": "); Object value = rs.getObject(i + 1); System.out.println(" Column Value: "+value+"\n"); } } } }
}
File: Main.java import java.sql.Timestamp; import java.util.List; import java.util.UUID; import javax.persistence.EntityManager; import javax.persistence.EntityManagerFactory; import javax.persistence.Persistence; import javax.persistence.Query; public class Main {
static EntityManagerFactory emf = Persistence.createEntityManagerFactory("JPAService"); static EntityManager em = emf.createEntityManager(); public static void main(String[] a) throws Exception { em.getTransaction().begin(); Student student = new Student(); student.setName("Joe"); em.persist(student); em.flush(); em.getTransaction().rumit(); Query query = em.createQuery("SELECT e FROM Student e"); List<Student> list = (List<Student>) query.getResultList(); System.out.println(list); em.close(); emf.close(); Helper.checkData(); }
}
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>
Mark Entity ID As Generated Value From 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: 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(); 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: 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>
Not Nullable ID
<source lang="java">
File: Student.java import javax.persistence.Column; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; @Entity public class Student {
@Id @Column(name = "ID", nullable = false) private int id; transient private String name;
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 String toString() { return "\n\nID:" + id + "\nName:" + name + "\n\n"; }
}
File: Helper.java import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.ResultSetMetaData; import java.sql.Statement; public class Helper {
public static void checkData() throws Exception { Class.forName("org.hsqldb.jdbcDriver"); Connection conn = DriverManager.getConnection("jdbc:hsqldb:data/tutorial", "sa", ""); Statement st = conn.createStatement(); ResultSet mrs = conn.getMetaData().getTables(null, null, null, new String[] { "TABLE" }); while (mrs.next()) { String tableName = mrs.getString(3); System.out.println("\n\n\n\nTable Name: "+ tableName); ResultSet rs = st.executeQuery("select * from " + tableName); ResultSetMetaData metadata = rs.getMetaData(); while (rs.next()) { System.out.println(" Row:"); for (int i = 0; i < metadata.getColumnCount(); i++) { System.out.println(" Column Name: "+ metadata.getColumnLabel(i + 1)+ ", "); System.out.println(" Column Type: "+ metadata.getColumnTypeName(i + 1)+ ": "); Object value = rs.getObject(i + 1); System.out.println(" Column Value: "+value+"\n"); } } } }
}
File: Main.java import java.sql.Timestamp; import java.util.List; import java.util.UUID; import javax.persistence.EntityManager; import javax.persistence.EntityManagerFactory; import javax.persistence.Persistence; import javax.persistence.Query; public class Main {
static EntityManagerFactory emf = Persistence.createEntityManagerFactory("JPAService"); static EntityManager em = emf.createEntityManager(); public static void main(String[] a) throws Exception { em.getTransaction().begin(); Student student = new Student(); student.setName("Joe"); em.persist(student); em.flush(); em.getTransaction().rumit(); Query query = em.createQuery("SELECT e FROM Student e"); List<Student> list = (List<Student>) query.getResultList(); System.out.println(list); em.close(); emf.close(); Helper.checkData(); }
}
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>
Relationship On Id
<source lang="java">
File: Department.java
import java.util.ArrayList; import java.util.Collection; import javax.persistence.Entity; import javax.persistence.Id; import javax.persistence.OneToMany; @Entity public class Department {
@Id private int id; private String name; @OneToMany(mappedBy="department") private Collection<Project> projects; public Department() { 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 deptName) { this.name = deptName; } public Collection<Project> getProjects() { return projects; } public String toString() { return "Department 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 Department createDepartment(String name, int id) { Department dept = new Department(); dept.setId(id); dept.setName(name); em.persist(dept); return dept; } public Project createProject(String name, int deptId) { Project proj = new Project(findDepartment(deptId)); proj.setName(name); em.persist(proj); return proj; } public Department findDepartment(int id) { return em.find(Department.class, id); } public Collection<Project> findAllProjects() { Query query = em.createQuery("SELECT p FROM Project p"); return (Collection<Project>) query.getResultList(); } public Collection<Department> findAllDepartments() { Query query = em.createQuery("SELECT d FROM Department d"); return (Collection<Department>) query.getResultList(); }
}
File: Project.java import javax.persistence.Column; import javax.persistence.Entity; import javax.persistence.Id; import javax.persistence.IdClass; import javax.persistence.JoinColumn; import javax.persistence.ManyToOne; @Entity @IdClass(ProjectId.class) public class Project {
@Id @Column(name = "DEPT_ID", insertable = false, updatable = false) private int deptId; @Id private String name; @ManyToOne @JoinColumn(name = "DEPT_ID") private Department department; public Project() { } public Project(Department dept) { this.department = dept; this.deptId = dept.getId(); } public String getName() { return name; } public void setName(String projectName) { this.name = projectName; } public int getDeptId() { return deptId; } public Department getDepartment() { return department; } public String toString() { return "Project name: " + getName(); }
}
File: ProjectId.java
import java.io.Serializable; public class ProjectId implements Serializable {
private int deptId; private String name; public ProjectId() {} public ProjectId(int deptId, String name) { this.deptId = deptId; this.name = name; } public String getName() { return name; } public int getId() { return deptId; } public boolean equals(Object o) { return ((o instanceof ProjectId) && name.equals(((ProjectId) o).getName()) && deptId == ((ProjectId) o).getId()); } public int hashCode() { return name.hashCode() + deptId; }
}
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(); Department dept = service.createDepartment("name",1); System.out.print("Created" + dept); Project proj = service.createProject("name", 1); System.out.print("Created" + proj); System.out.println("Project:"); for (Project p : service.findAllProjects()) { System.out.println(p + " " + p.getDepartment()); } System.out.println("Departments:"); for (Department d : service.findAllDepartments()) { System.out.println(d + " " + d.getProjects().size()); } util.checkData("select * from Project"); em.getTransaction().rumit(); 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>
Sequence Id Generation
<source lang="java">
File: Professor.java import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.Id; import javax.persistence.SequenceGenerator; @Entity public class Professor {
@SequenceGenerator(name="Emp_Gen", sequenceName="Emp_Seq") @Id @GeneratedValue(generator="Emp_Gen") private int id; private String name; private long salary;
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: 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(); util.executeSQLCommand("CREATE SEQUENCE Emp_Seq;"); EntityManagerFactory emf = Persistence.createEntityManagerFactory("ProfessorService"); EntityManager em = emf.createEntityManager(); ProfessorService service = new ProfessorService(em); em.getTransaction().begin(); Professor emp = service.createProfessor("name", 100); em.getTransaction().rumit(); System.out.println("Persisted " + emp); util.checkData("select * from Professor"); 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>
Set IdClass for Compound Key
<source lang="java">
File: Professor.java
import java.util.ArrayList; import java.util.Collection; import javax.persistence.Entity; import javax.persistence.Id; import javax.persistence.OneToMany; @Entity public class Professor {
@Id private int id; private String name; @OneToMany(mappedBy="employee") private Collection<ProjectAssignment> assignments; public Professor() { assignments = new ArrayList<ProjectAssignment>(); } 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 Collection<ProjectAssignment> getAssignments() { return assignments; } public String toString() { return "Professor id: " + getId() + " name: " + getName(); }
}
File: ProfessorService.java import java.util.Collection; import java.util.Date; 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, int id) { Project emp = new Project(); emp.setId(id); emp.setName(name); em.persist(emp); return emp; } public Professor createProfessor(String country, int id, String name) { Professor emp = new Professor(); emp.setId(id); emp.setName(name); em.persist(emp); return emp; } public void addProfessorProject(int id, int projId) { Professor emp = findProfessor(id); Project proj = em.find(Project.class, projId); ProjectAssignment assign = new ProjectAssignment(emp, proj); em.persist(assign); emp.getAssignments().add(assign); proj.getAssignments().add(assign); } 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(); } public Collection<Project> findAllProjects() { Query query = em.createQuery("SELECT p FROM Project p"); return (Collection<Project>) query.getResultList(); }
}
File: Project.java
import java.util.ArrayList; import java.util.Collection; import javax.persistence.Entity; import javax.persistence.Id; import javax.persistence.OneToMany; @Entity public class Project {
@Id private int id; private String name; @OneToMany(mappedBy="project") private Collection<ProjectAssignment> assignments; public Project() { assignments = new ArrayList<ProjectAssignment>(); } 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<ProjectAssignment> getAssignments() { return assignments; } public String toString() { return getClass().getName().substring(getClass().getName().lastIndexOf(".")+1) + " no: " + getId() + ", name: " + getName(); }
}
File: ProjectAssignment.java
import java.util.Date; import javax.persistence.Column; import javax.persistence.Entity; import javax.persistence.Id; import javax.persistence.IdClass; import javax.persistence.JoinColumn; import javax.persistence.ManyToOne; import javax.persistence.Table; import javax.persistence.Temporal; import javax.persistence.TemporalType; @Entity @Table(name = "EMP_PROJECT") @IdClass(ProjectAssignmentId.class) public class ProjectAssignment {
@Id @Column(name = "EMP_ID", insertable = false, updatable = false) private int empId; @Id @Column(name = "PROJECT_ID", insertable = false, updatable = false) private int projectId; @ManyToOne @JoinColumn(name = "EMP_ID") Professor employee; @ManyToOne @JoinColumn(name = "PROJECT_ID") Project project;
public ProjectAssignment() { } public ProjectAssignment(Professor emp, Project proj) { this.empId = emp.getId(); this.employee = emp; this.projectId = proj.getId(); this.project = proj; } public int getEmpId() { return empId; } public Professor getProfessor() { return employee; } public int getProjectId() { return projectId; } public Project getProject() { return project; }
}
File: ProjectAssignmentId.java
import java.io.Serializable; public class ProjectAssignmentId implements Serializable {
private int empId; private int projectId; public ProjectAssignmentId() {} public ProjectAssignmentId(int empId, int projectId) { this.empId = empId; this.projectId = projectId; } public int getEmpId() { return empId; } public int getProjectId() { return projectId; } public boolean equals(Object o) { return ((o instanceof ProjectAssignmentId) && empId == ((ProjectAssignmentId)o).getEmpId() && projectId == ((ProjectAssignmentId) o).getProjectId()); } public int hashCode() { return empId + projectId; }
}
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(); service.createProject("proj", 1); service.createProfessor("country", 1, "name"); service.addProfessorProject(1, 1); System.out.println("Professors:"); for (Professor emp : service.findAllProfessors()) { System.out.print(emp + " with " + emp.getAssignments().size() + " assignments"); } System.out.println("Projects:"); for (Project p : service.findAllProjects()) { System.out.print(p + " with " + p.getAssignments().size() + " assignments"); } 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>
Set Primary Key By Yourself
<source lang="java">
File: Gender.java public enum Gender {
MALE, FEMALE
}
File: Student.java import java.util.Date; import javax.persistence.Entity; import javax.persistence.EnumType; import javax.persistence.Enumerated; import javax.persistence.Id; @Entity public class Student {
@Id private long id = 0; private String name; private Date dateOfBirth = new Date(); @Enumerated(EnumType.ORDINAL) private Gender gender; public Date getDateOfBirth() { return dateOfBirth; } public void setDateOfBirth(Date dateOfBirth) { this.dateOfBirth = dateOfBirth; } public long getId() { return id; } public void setId(long id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public Gender getGender() { return gender; } public void setGender(Gender gender) { this.gender = gender; } public String toString() { return "\n\nID:" + id + "\nName:" + name + "\nBirthday:" + dateOfBirth + "\nGender:" + gender+"\n\n"; }
}
File: JPADAO.java import java.util.Date; import java.util.List; import javax.persistence.EntityManager; import javax.persistence.EntityManagerFactory; import javax.persistence.Persistence; import javax.persistence.Query; public class JPADAO {
EntityManagerFactory emf = Persistence.createEntityManagerFactory("JPAService"); EntityManager em = emf.createEntityManager(); public void create() { em.getTransaction().begin(); Student student = new Student(); student.setId(1); student.setName("Joe"); student.setDateOfBirth(new Date()); student.setGender(Gender.FEMALE); em.persist(student); em.flush(); em.getTransaction().rumit(); } public void search() { Query q = em.createQuery("select m from Student m"); for (Student m : (List<Student>) q.getResultList()) { System.out.println(m); } } public void close() { em.close(); emf.close(); }
}
File: Helper.java import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.ResultSetMetaData; import java.sql.Statement; public class Helper {
public static void checkData() throws Exception { Class.forName("org.hsqldb.jdbcDriver"); Connection conn = DriverManager.getConnection("jdbc:hsqldb:data/tutorial", "sa", ""); Statement st = conn.createStatement(); ResultSet mrs = conn.getMetaData().getTables(null, null, null, new String[] { "TABLE" }); while (mrs.next()) { String tableName = mrs.getString(3); System.out.println("\n\n\n\nTable Name: "+ tableName); ResultSet rs = st.executeQuery("select * from " + tableName); ResultSetMetaData metadata = rs.getMetaData(); while (rs.next()) { System.out.println(" Row:"); for (int i = 0; i < metadata.getColumnCount(); i++) { System.out.println(" Column Name: "+ metadata.getColumnLabel(i + 1)+ ", "); System.out.println(" Column Type: "+ metadata.getColumnTypeName(i + 1)+ ": "); Object value = rs.getObject(i + 1); System.out.println(" Column Value: "+value+"\n"); } } } }
}
File: Main.java import java.util.List; import javax.persistence.EntityManager; import javax.persistence.EntityManagerFactory; import javax.persistence.Persistence; import javax.persistence.Query; public class Main {
public static void main(String[] a) throws Exception { JPADAO jpaDao = new JPADAO(); jpaDao.create(); jpaDao.search(); jpaDao.close(); Helper.checkData(); }
} /*
[java] Table Name: STUDENT [java] Row: [java] Column Name: ID, [java] Column Type: BIGINT: [java] Column Value: 1 [java] Column Name: DATEOFBIRTH, [java] Column Type: TIMESTAMP: [java] Column Value: 2008-11-05 13:32:00.35 [java] Column Name: GENDER, [java] Column Type: VARCHAR: [java] Column Value: FEMALE [java] Column Name: NAME, [java] Column Type: VARCHAR: [java] Column Value: Joe
- /
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>
Set Primary Key Joined Column For Secondary Table
<source lang="java">
File: Professor.java import javax.persistence.Basic; import javax.persistence.Column; import javax.persistence.Entity; import javax.persistence.FetchType; import javax.persistence.Id; import javax.persistence.IdClass; import javax.persistence.JoinColumn; import javax.persistence.JoinColumns; import javax.persistence.Lob; import javax.persistence.ManyToOne; import javax.persistence.PrimaryKeyJoinColumn; import javax.persistence.SecondaryTable; import javax.persistence.SecondaryTables; @Entity @SecondaryTable(name = "EMP_LOB", pkJoinColumns = {
@PrimaryKeyJoinColumn(name = "ID", referencedColumnName = "ID") })
public class Professor {
private String country; @Id private int id; private String name; @Basic(fetch = FetchType.LAZY) @Lob @Column(table = "EMP_LOB") private byte[] photo;
public int getId() { return id; } public void setId(int id) { this.id = id; } public String getCountry() { return country; } public void setCountry(String country) { this.country = country; } public String getName() { return name; } public void setName(String name) { this.name = name; }
public String toString() { return "Professor id: " + getId() + " name: " + getName() + " country: " + getCountry(); }
}
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 country, int id, String name) { Professor emp = new Professor(); emp.setCountry(country); emp.setId(id); emp.setName(name); em.persist(emp); return 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(); service.createProfessor("country", 1, "name"); System.out.println("Professors:"); for (Professor emp : service.findAllProfessors()) { System.out.print(emp); } util.checkData("select * from Professor"); 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>
Use UUID As Primary Key
<source lang="java">
File: Student.java import javax.persistence.Basic; import javax.persistence.Column; import javax.persistence.Entity; import javax.persistence.FetchType; import javax.persistence.Id; import javax.persistence.Lob; @Entity public class Student {
@Id private String id; private String name;
public String getId() { return id; } public void setId(String id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; }
public String toString() { return "\n\nID:" + id + "\nName:" + name + "\n\n"; }
}
File: Helper.java import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.ResultSetMetaData; import java.sql.Statement; public class Helper {
public static void checkData() throws Exception { Class.forName("org.hsqldb.jdbcDriver"); Connection conn = DriverManager.getConnection("jdbc:hsqldb:data/tutorial", "sa", ""); Statement st = conn.createStatement(); ResultSet mrs = conn.getMetaData().getTables(null, null, null, new String[] { "TABLE" }); while (mrs.next()) { String tableName = mrs.getString(3); System.out.println("\n\n\n\nTable Name: "+ tableName); ResultSet rs = st.executeQuery("select * from " + tableName); ResultSetMetaData metadata = rs.getMetaData(); while (rs.next()) { System.out.println(" Row:"); for (int i = 0; i < metadata.getColumnCount(); i++) { System.out.println(" Column Name: "+ metadata.getColumnLabel(i + 1)+ ", "); System.out.println(" Column Type: "+ metadata.getColumnTypeName(i + 1)+ ": "); Object value = rs.getObject(i + 1); System.out.println(" Column Value: "+value+"\n"); } } } }
}
File: Main.java import java.util.List; import java.util.UUID; import javax.persistence.EntityManager; import javax.persistence.EntityManagerFactory; import javax.persistence.Persistence; import javax.persistence.Query; public class Main {
static EntityManagerFactory emf = Persistence.createEntityManagerFactory("JPAService"); static EntityManager em = emf.createEntityManager(); public static void main(String[] a) throws Exception { em.getTransaction().begin(); Student student = new Student(); student.setId(UUID.randomUUID().toString() ); student.setName("Joe"); em.persist(student); em.flush(); em.getTransaction().rumit(); Query query = em.createQuery("SELECT e FROM Student e"); List<Student> list = (List<Student>) query.getResultList(); System.out.println(list); em.close(); emf.close(); Helper.checkData(); }
}
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>
Using Primary Key Column as Joined Column
<source lang="java">
File: ParkingSpace.java
import javax.persistence.Entity; import javax.persistence.Id; import javax.persistence.OneToOne; import javax.persistence.PrimaryKeyJoinColumn; import javax.persistence.Table; @Entity public class ParkingSpace {
@Id private int id; private int lot; private String location; @OneToOne @PrimaryKeyJoinColumn private Professor employee; public int getId() { return id; } public void setId(int id) { this.id = id; } public int getLot() { return lot; } public void setLot(int lot) { this.lot = lot; } public String getLocation() { return location; } public void setLocation(String deptName) { this.location = deptName; } public Professor getProfessor() { return employee; } public void setProfessor(Professor employee) { this.employee = employee; } public String toString() { return "ParkingSpace id: " + getId() + " lot: " + getLot() + ", location: " + getLocation(); }
}
File: Professor.java
import javax.persistence.Entity; import javax.persistence.Id; import javax.persistence.OneToOne; @Entity public class Professor {
@Id private int id; private String name; private long salary; @OneToOne(mappedBy="employee") private ParkingSpace parkingSpace; 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 ParkingSpace getParkingSpace() { return parkingSpace; } public void setParkingSpace(ParkingSpace parkingSpace) { this.parkingSpace = parkingSpace; } public String toString() { return "Professor id: " + getId() + " name: " + getName() + " with " + getParkingSpace(); }
}
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(int id, String name, long salary) { Professor emp = new Professor(); emp.setId(id); emp.setName(name); emp.setSalary(salary); em.persist(emp); return emp; } public Collection<Professor> findAllProfessors() { Query query = em.createQuery("SELECT e FROM Professor e"); return (Collection<Professor>) query.getResultList(); } public ParkingSpace createParkingSpace(Professor emp, int lot, String location) { ParkingSpace space = new ParkingSpace(); space.setId(emp.getId()); space.setLot(lot); space.setLocation(location); emp.setParkingSpace(space); space.setProfessor(emp); em.persist(space); return space; } public Collection<ParkingSpace> findAllParkingSpaces() { Query query = em.createQuery("SELECT p FROM ParkingSpace p"); return (Collection<ParkingSpace>) 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 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(1, "empName", 100L); service.createParkingSpace(emp, 1, "location"); System.out.println("Created " + emp); 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<ParkingSpace> pSpaces = service.findAllParkingSpaces(); if (pSpaces.isEmpty()) { System.out.println("No ParkingSpaces found "); } else { System.out.println("Found ParkingSpaces:"); for (ParkingSpace pSpace : pSpaces) { System.out.println(pSpace); } } util.checkData("select * from Professor"); util.checkData("select * from ParkingSpace"); 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>
Using System MilliSeconds As Key
<source lang="java">
File: Message.java
import java.util.Date; import javax.persistence.Basic; import javax.persistence.Entity; import javax.persistence.Id; @Entity public class Message {
@Id private long id = System.currentTimeMillis(); @Basic private String message; @Basic private Date created = new Date(); public Message() { } public Message(String msg) { message = msg; } public void setId(long val) { id = val; } public long getId() { return id; } public void setMessage(String msg) { message = msg; } public String getMessage() { return message; } public void setCreated(Date date) { created = date; } public Date getCreated() { return created; }
}
File: ProfessorService.java import java.util.List; import javax.persistence.EntityManager; import javax.persistence.Query; public class ProfessorService {
protected EntityManager em; public ProfessorService(EntityManager em) { this.em = em; } public void messageCreateAndList() { em.persist(new Message("Hello Persistence!")); Query q = em.createQuery("select m from Message m"); for (Message m : (List<Message>) q.getResultList()) { System.out.println(m.getMessage() + " (created on: " + m.getCreated() + ")"); } }
}
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();
service.messageCreateAndList(); util.checkData("select * from Message"); 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>