в 18:01, 31 мая 2010

2010-05-31T18:01:48Z

Новая страница

== Many To Many Bidirectional Mapping ==



<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.ManyToMany;
@Entity
public class Professor {
@Id @GeneratedValue(strategy=GenerationType.IDENTITY)
private int id;
private String name;
private long salary;

@ManyToMany
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 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();
}
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();
}
}

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", 100L);
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>



== Many To Many Joined Table ==



<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>



== Many to Many Mapping Key Table Is Created Automatically ==



<source lang="java">

File: Professor.java

import java.util.ArrayList;
import java.util.Collection;
import java.util.Date;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.ManyToMany;
import javax.persistence.Temporal;
import javax.persistence.TemporalType;
@Entity
public class Professor {
@Id
private int id;
private String name;
private long salary;
@Temporal(TemporalType.DATE)
private Date startDate;

@ManyToMany
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 void setProjects(Collection<Project> projects) {
this.projects = projects;
}
public void setSalary(long salary) {
this.salary = salary;
}
public void setStartDate(Date startDate) {
this.startDate = startDate;
}
public long getSalary() {
return salary;
}
public Date getStartDate() {
return startDate;
}

public Collection<Project> getProjects() {
return projects;
}

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

File: ProfessorService.java
import java.util.Collection;
import javax.persistence.EntityManager;
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 Project createProject(String name) {
Project space = new Project();
space.setName(name);
em.persist(space);
return space;
}

public Collection<Professor> findAllProfessors() {
return (Collection<Professor>) em.createQuery("SELECT e FROM Professor e").getResultList();
}
public void assignProfessorToProject(int empId, int projectId) {
Project project = em.find(Project.class, projectId);
Professor employee = em.find(Professor.class, empId);
project.getProfessors().add(employee);
employee.getProjects().add(project);
}
public Collection<Project> findAllProjects() {
return (Collection<Project>) em.createQuery("SELECT p FROM Project p").getResultList();
}
}

File: Project.java

import java.util.ArrayList;
import java.util.Collection;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.ManyToMany;
@Entity
public class Project {
@Id
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 String getName() {
return name;
}

public Collection<Professor> getProfessors() {
return employees;
}

public void setProfessors(Collection<Professor> employees) {
this.employees = employees;
}
public void setId(int id) {
this.id = id;
}
public void setName(String name) {
this.name = name;
}
public String toString() {
return "Project id: " + getId() + ", name: " + getName();
}
}

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("name",100);
Project proj = service.createProject("proj name");

service.assignProfessorToProject(emp.getId(),proj.getId());
for (Object o : service.findAllProfessors()) {
System.out.println(o );
}
for (Object o : service.findAllProjects()) {
System.out.println(o);
}

util.checkData("select * from Professor");
util.checkData("select * from Project");

util.checkData("select * from Professor_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>



== Many To Many Mapping Remove Action ==



<source lang="java">

File: Project.java

import java.util.ArrayList;
import java.util.Collection;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.ManyToMany;
@Entity
public class Project {
@Id
protected int id;
protected String name;
@ManyToMany(mappedBy="projects")
private Collection<Student> students;
public Project() {
students = new ArrayList<Student>();
}
public void setId(int i){
id = i;
}
public int getId() {
return id;
}

public String getName() {
return name;
}

public Collection<Student> getStudents() {
return students;
}

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

File: Student.java
import java.util.ArrayList;
import java.util.Collection;
import java.util.Date;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.ManyToMany;
import javax.persistence.Temporal;
import javax.persistence.TemporalType;
@Entity
public class Student {
@Id
private int id;
private String name;

@ManyToMany
private Collection<Project> projects;
public Student() {
projects = new ArrayList<Project>();
}
public int getId() {
return id;
}

public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}

public Collection<Project> getProjects() {
return projects;
}

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

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 {
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(1);
em.persist(student);

Project dept = new Project();
dept.setId(1);
em.persist(dept);

em.flush();

em.remove(dept);

Query query = em.createQuery("SELECT e FROM Student e");
List<Student> list = (List<Student>) query.getResultList();
System.out.println(list);

query = em.createQuery("SELECT d FROM Project d");
List<Project> dList = (List<Project>) query.getResultList();
System.out.println(dList);

em.getTransaction().rumit();
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>

Java/JPA/Many to Many Mapping - История изменений

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в 18:01, 31 мая 2010

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