Welkom bij de Hibernate Named Query Example Tutorial. We hebben gezien hoe we HQL en Native SQL Query in Hibernate kunnen gebruiken. Als er veel queries zijn, kunnen ze voor een rommelige code zorgen omdat alle queries door het hele project verspreid zijn. Daarom biedt Hibernate Named Query aan waarmee we ze op een centrale locatie kunnen definiëren en overal in de code kunnen gebruiken. We kunnen genoemde queries maken voor zowel HQL als Native SQL.
Hibernate Named Query
Hibernate Named Query kan worden gedefinieerd in Hibernate mapping-bestanden of door het gebruik van JPA-annotaties @NamedQuery en @NamedNativeQuery. Vandaag zullen we beide benaderingen bekijken en hoe Hibernate named query te gebruiken in een eenvoudige toepassing. We zullen dezelfde databasetabellen gebruiken als in HQL Example, dus u kunt dat bericht raadplegen voor het SQL-script voor het instellen van de database. Voor ons Hibernate named query voorbeeldproject zullen we annotaties gebruiken voor de Hibernate-mapping. We zullen echter enkele named queries maken in zowel mapping-bestanden als in entity bean-klassen. Onze uiteindelijke projectstructuur ziet eruit als de onderstaande afbeelding, waarbij we ons voornamelijk zullen richten op de componenten die verband houden met Hibernate Named Query. 
Hibernate Configuration XML
hibernate.cfg.xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration SYSTEM "https://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="hibernate.connection.password">pankaj123</property>
<property name="hibernate.connection.url">jdbc:mysql://localhost/TestDB</property>
<property name="hibernate.connection.username">pankaj</property>
<property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
<property name="hibernate.current_session_context_class">thread</property>
<property name="hibernate.show_sql">true</property>
<mapping class="com.journaldev.hibernate.model.Employee" />
<mapping class="com.journaldev.hibernate.model.Address" />
<mapping resource="named-queries.hbm.xml" />
</session-factory>
</hibernate-configuration>
Hibernate Named Query XML
We hebben een Hibernate-toewijzingsbestand dat alleen HQL-naamqueries en Native SQL-naamqueries bevat. named-queries.hbm.xml
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"https://hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
<query name="HQL_GET_ALL_EMPLOYEE">from Employee</query>
<query name="HQL_GET_EMPLOYEE_BY_ID">
<![CDATA[from Employee where emp_id = :id]]>
</query>
<query name="HQL_GET_EMPLOYEE_BY_SALARY">
<![CDATA[from Employee where emp_salary > :salary]]>
</query>
<sql-query name="SQL_GET_ALL_EMPLOYEE">
<![CDATA[select emp_id, emp_name, emp_salary from Employee]]>
</sql-query>
<sql-query name="SQL_GET_ALL_EMP_ADDRESS">
<![CDATA[select {e.*}, {a.*} from Employee e join Address a ON e.emp_id=a.emp_id]]>
<return alias="e" class="com.journaldev.hibernate.model.Employee" />
<return-join alias="a" property="e.address"></return-join>
</sql-query>
</hibernate-mapping>
Het query-element wordt gebruikt voor HQL-naamqueries en het sql-query-element wordt gebruikt voor native SQL-naamqueries. We kunnen het return-element gebruiken om de entiteit aan te geven waaraan het resultaatset zal worden toegewezen. return-join wordt gebruikt wanneer we een join van meerdere tabellen hebben. We moeten CDATA gebruiken om onze Hibernate-naamquery te declareren om ervoor te zorgen dat deze als gegevens wordt behandeld, anders zullen < en > tekens ons toewijzings-XML-bestand verstoren.
Hibernate Named Query @NamedQuery Annotatie
We hebben twee modelklassen – Employee en Address. We hebben naamqueries gedefinieerd in de klasse Address zoals hieronder weergegeven.
package com.journaldev.hibernate.model;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.NamedNativeQueries;
import javax.persistence.NamedNativeQuery;
import javax.persistence.NamedQueries;
import javax.persistence.NamedQuery;
import javax.persistence.OneToOne;
import javax.persistence.PrimaryKeyJoinColumn;
import javax.persistence.Table;
import org.hibernate.annotations.GenericGenerator;
import org.hibernate.annotations.Parameter;
@Entity
@Table(name = "ADDRESS")
@NamedQueries({ @NamedQuery(name = "@HQL_GET_ALL_ADDRESS",
query = "from Address") })
@NamedNativeQueries({ @NamedNativeQuery(name = "@SQL_GET_ALL_ADDRESS",
query = "select emp_id, address_line1, city, zipcode from Address") })
public class Address {
@Id
@Column(name = "emp_id", unique = true, nullable = false)
@GeneratedValue(generator = "gen")
@GenericGenerator(name = "gen", strategy = "foreign", parameters = { @Parameter(name = "property", value = "employee") })
private long id;
@Column(name = "address_line1")
private String addressLine1;
@Column(name = "zipcode")
private String zipcode;
@Column(name = "city")
private String city;
@OneToOne
@PrimaryKeyJoinColumn
private Employee employee;
public long getId() {
return id;
}
public void setId(long id) {
this.id = id;
}
public String getAddressLine1() {
return addressLine1;
}
public void setAddressLine1(String addressLine1) {
this.addressLine1 = addressLine1;
}
public String getZipcode() {
return zipcode;
}
public void setZipcode(String zipcode) {
this.zipcode = zipcode;
}
public String getCity() {
return city;
}
public void setCity(String city) {
this.city = city;
}
public Employee getEmployee() {
return employee;
}
public void setEmployee(Employee employee) {
this.employee = employee;
}
@Override
public String toString() {
return "AddressLine1= " + addressLine1 + ", City=" + city
+ ", Zipcode=" + zipcode;
}
}
Hibernate Named Query Test Program
Laten we een testprogramma schrijven om alle hierboven gedefinieerde Hibernate genoemde queries te gebruiken.
package com.journaldev.hibernate.main;
import java.util.List;
import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import com.journaldev.hibernate.model.Address;
import com.journaldev.hibernate.model.Employee;
import com.journaldev.hibernate.util.HibernateUtil;
public class HibernateNamedQueryExample {
@SuppressWarnings("unchecked")
public static void main(String[] args) {
// Voorbereidend werk
SessionFactory sessionFactory = HibernateUtil.getSessionFactory();
Session session = sessionFactory.getCurrentSession();
Transaction tx = session.beginTransaction();
// HQL Named Query Voorbeeld
Query query = session.getNamedQuery("HQL_GET_ALL_EMPLOYEE");
List empList = query.list();
for (Employee emp : empList) {
System.out.println("List of Employees::" + emp.getId() + ","
+ emp.getAddress().getCity());
}
query = session.getNamedQuery("HQL_GET_EMPLOYEE_BY_ID");
query.setInteger("id", 2);
Employee emp = (Employee) query.uniqueResult();
System.out.println("Employee Name=" + emp.getName() + ", City="
+ emp.getAddress().getCity());
query = session.getNamedQuery("HQL_GET_EMPLOYEE_BY_SALARY");
query.setInteger("salary", 200);
empList = query.list();
for (Employee emp1 : empList) {
System.out.println("List of Employees::" + emp1.getId() + ","
+ emp1.getSalary());
}
query = session.getNamedQuery("@HQL_GET_ALL_ADDRESS");
List addressList = query.list();
for (Address addr : addressList) {
System.out.println("List of Address::" + addr.getId() + "::"
+ addr.getZipcode() + "::" + addr.getEmployee().getName());
}
// Native SQL Named Query Voorbeeld
query = session.getNamedQuery("@SQL_GET_ALL_ADDRESS");
List addressObjArray = query.list();
for(Object[] row : addressObjArray){
for(Object obj : row){
System.out.print(obj + "::");
}
System.out.println("\n");
}
query = session.getNamedQuery("SQL_GET_ALL_EMP_ADDRESS");
addressObjArray = query.list();
for(Object[] row : addressObjArray){
Employee e = (Employee) row[0];
System.out.println("Employee Info::"+e);
Address a = (Address) row[1];
System.out.println("Address Info::"+a);
}
// Terugrollen om de testgegevens op te slaan
tx.commit();
// Hibernate-resources sluiten
sessionFactory.close();
}
}
Wanneer we het bovenstaande programma uitvoeren met de testgegevens die we hebben, produceert het de volgende output.
Hibernate: select employee0_.emp_id as emp_id1_1_, employee0_.emp_name as emp_name2_1_, employee0_.emp_salary as emp_sala3_1_ from EMPLOYEE employee0_
Hibernate: select address0_.emp_id as emp_id1_0_0_, address0_.address_line1 as address_2_0_0_, address0_.city as city3_0_0_, address0_.zipcode as zipcode4_0_0_, employee1_.emp_id as emp_id1_1_1_, employee1_.emp_name as emp_name2_1_1_, employee1_.emp_salary as emp_sala3_1_1_ from ADDRESS address0_ left outer join EMPLOYEE employee1_ on address0_.emp_id=employee1_.emp_id where address0_.emp_id=?
Hibernate: select address0_.emp_id as emp_id1_0_0_, address0_.address_line1 as address_2_0_0_, address0_.city as city3_0_0_, address0_.zipcode as zipcode4_0_0_, employee1_.emp_id as emp_id1_1_1_, employee1_.emp_name as emp_name2_1_1_, employee1_.emp_salary as emp_sala3_1_1_ from ADDRESS address0_ left outer join EMPLOYEE employee1_ on address0_.emp_id=employee1_.emp_id where address0_.emp_id=?
Hibernate: select address0_.emp_id as emp_id1_0_0_, address0_.address_line1 as address_2_0_0_, address0_.city as city3_0_0_, address0_.zipcode as zipcode4_0_0_, employee1_.emp_id as emp_id1_1_1_, employee1_.emp_name as emp_name2_1_1_, employee1_.emp_salary as emp_sala3_1_1_ from ADDRESS address0_ left outer join EMPLOYEE employee1_ on address0_.emp_id=employee1_.emp_id where address0_.emp_id=?
Hibernate: select address0_.emp_id as emp_id1_0_0_, address0_.address_line1 as address_2_0_0_, address0_.city as city3_0_0_, address0_.zipcode as zipcode4_0_0_, employee1_.emp_id as emp_id1_1_1_, employee1_.emp_name as emp_name2_1_1_, employee1_.emp_salary as emp_sala3_1_1_ from ADDRESS address0_ left outer join EMPLOYEE employee1_ on address0_.emp_id=employee1_.emp_id where address0_.emp_id=?
List of Employees::1,San Jose
List of Employees::2,Santa Clara
List of Employees::3,Bangalore
List of Employees::4,New Delhi
Hibernate: select employee0_.emp_id as emp_id1_1_, employee0_.emp_name as emp_name2_1_, employee0_.emp_salary as emp_sala3_1_ from EMPLOYEE employee0_ where emp_id=?
Employee Name=David, City=Santa Clara
Hibernate: select employee0_.emp_id as emp_id1_1_, employee0_.emp_name as emp_name2_1_, employee0_.emp_salary as emp_sala3_1_ from EMPLOYEE employee0_ where emp_salary>?
List of Employees::3,300.0
List of Employees::4,400.0
Hibernate: select address0_.emp_id as emp_id1_0_, address0_.address_line1 as address_2_0_, address0_.city as city3_0_, address0_.zipcode as zipcode4_0_ from ADDRESS address0_
List of Address::1::95129::Pankaj
List of Address::2::95051::David
List of Address::3::560100::Lisa
List of Address::4::100100::Jack
Hibernate: select emp_id, address_line1, city, zipcode from Address
1::Albany Dr::San Jose::95129::
2::Arques Ave::Santa Clara::95051::
3::BTM 1st Stage::Bangalore::560100::
4::City Centre::New Delhi::100100::
Hibernate: select e.emp_id as emp_id1_1_0_, e.emp_name as emp_name2_1_0_, e.emp_salary as emp_sala3_1_0_, a.emp_id as emp_id1_0_1_, a.address_line1 as address_2_0_1_, a.city as city3_0_1_, a.zipcode as zipcode4_0_1_ from Employee e join Address a ON e.emp_id=a.emp_id
Employee Info::Id= 1, Name= Pankaj, Salary= 100.0, {Address= AddressLine1= Albany Dr, City=San Jose, Zipcode=95129}
Address Info::AddressLine1= Albany Dr, City=San Jose, Zipcode=95129
Employee Info::Id= 2, Name= David, Salary= 200.0, {Address= AddressLine1= Arques Ave, City=Santa Clara, Zipcode=95051}
Address Info::AddressLine1= Arques Ave, City=Santa Clara, Zipcode=95051
Employee Info::Id= 3, Name= Lisa, Salary= 300.0, {Address= AddressLine1= BTM 1st Stage, City=Bangalore, Zipcode=560100}
Address Info::AddressLine1= BTM 1st Stage, City=Bangalore, Zipcode=560100
Employee Info::Id= 4, Name= Jack, Salary= 400.0, {Address= AddressLine1= City Centre, City=New Delhi, Zipcode=100100}
Address Info::AddressLine1= City Centre, City=New Delhi, Zipcode=100100
Belangrijke punten van Hibernate Named Query
Enkele belangrijke punten over Hibernate Named Query zijn;
- Hibernate Named Query helpt ons bij het groeperen van queries op een centrale locatie in plaats van ze overal in de code te laten verspreiden.
- Hibernate Named Query-syntax wordt gecontroleerd wanneer de hibernate-sessiefabriek wordt gemaakt, waardoor de toepassing snel mislukt in geval van fouten in de genoemde queries.
- Hibernate Named Query is globaal, wat betekent dat het eenmaal gedefinieerd kan worden gebruikt in de hele toepassing.
- Een van de belangrijkste nadelen van een genoemde query is dat het moeilijk te debuggen is, omdat we moeten achterhalen waar het is gedefinieerd.
Dat is alles voor het Hibernate Named Query Voorbeeld, u kunt het voorbeeldproject downloaden vanaf onderstaande link.
Source:
https://www.digitalocean.com/community/tutorials/hibernate-named-query-example-namedquery