File: Employee.java
import java.io.Serializable;
import java.util.ArrayList;
import java.util.Collection;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.EntityResult;
import javax.persistence.FieldResult;
import javax.persistence.Id;
import javax.persistence.IdClass;
import javax.persistence.JoinColumn;
import javax.persistence.JoinColumns;
import javax.persistence.ManyToOne;
import javax.persistence.OneToMany;
import javax.persistence.SqlResultSetMapping;
import javax.persistence.Table;
@Entity
@Table(name="EMP")
@IdClass(EmployeeId.class)
@SqlResultSetMapping(
name="EmployeeAndManager",
entities={
@EntityResult(entityClass=Employee.class),
@EntityResult(
entityClass=Employee.class,
fields={
@FieldResult(name="country", column="MGR_COUNTRY"),
@FieldResult(name="id", column="MGR_ID"),
@FieldResult(name="name", column="MGR_NAME"),
@FieldResult(name="manager.country", column="MGR_MGR_COUNTRY"),
@FieldResult(name="manager.id", column="MGR_MGR_ID")
}
)
}
)
public class Employee {
@Id private String country;
@Id
private int id;
private String name;
@ManyToOne
@JoinColumns({
@JoinColumn(name="MANAGER_COUNTRY", referencedColumnName="COUNTRY"),
@JoinColumn(name="MANAGER_ID", referencedColumnName="ID")
})
private Employee manager;
@OneToMany(mappedBy="manager")
private Collection<Employee> directs = new ArrayList<Employee>();
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 Collection<Employee> getDirects() {
return directs;
}
public Employee getManager() {
return manager;
}
public void setManager(Employee manager) {
this.manager = manager;
}
}
class EmployeeId implements Serializable {
private String country;
private int id;
public EmployeeId() {}
public EmployeeId(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 EmployeeId) &&
country.equals(((EmployeeId)o).getCountry()) &&
id == ((EmployeeId) o).getId());
}
public int hashCode() {
return country.hashCode() + id;
}
}
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();
Query query = em.createNativeQuery(
"SELECT e.country, e.id, e.name, " +
"e.manager_country, e.manager_id, m.country AS mgr_country, " +
"m.id AS mgr_id, m.name AS mgr_name," +
"m.manager_country AS mgr_mgr_country, m.manager_id AS mgr_mgr_id " +
"FROM emp e, emp m ",
"EmployeeAndManager");
List list = query.getResultList();
em.getTransaction().commit();
em.close();
emf.close();
Helper.checkData();
}
}
File: persistence.xml
<persistence xmlns="http://java.sun.com/xml/ns/persistence"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence" version="1.0">
<persistence-unit name="JPAService" transaction-type="RESOURCE_LOCAL">
<properties>
<property name="hibernate.dialect" value="org.hibernate.dialect.HSQLDialect"/>
<property name="hibernate.hbm2ddl.auto" value="update"/>
<property name="hibernate.connection.driver_class" value="org.hsqldb.jdbcDriver"/>
<property name="hibernate.connection.username" value="sa"/>
<property name="hibernate.connection.password" value=""/>
<property name="hibernate.connection.url" value="jdbc:hsqldb:data/tutorial"/>
</properties>
</persistence-unit>
</persistence>
Download: JPA-SqlResultSetMappingWithEntityResultAndFieldResult.zip( 5,291 k)