欢迎使用Hibernate命名查询示例教程。我们看到了如何在Hibernate中使用HQL和Native SQL Query。如果有很多查询，那么它们将导致代码混乱，因为所有查询将分散在整个项目中。这就是Hibernate提供命名查询的原因，我们可以在中心位置定义并在代码中的任何位置使用它们。我们可以为HQL和Native SQL创建命名查询。
目录[ 隐藏 ]
冬眠命名查询可以在Hibernate映射文件或者通过使用JPA注释来定义@NamedQuery和@NamedNativeQuery。今天我们将研究它们以及如何在一个简单的应用程序中使用hibernate命名查询。
我们将使用与HQL示例中相同的数据库表，因此您可以检查数据库设置sql脚本的帖子。
对于我们的hibernate命名查询示例项目，我们将使用注释进行hibernate映射。但是，我们将在映射文件和实体bean类中创建一些命名查询。我们的最终项目结构如下图所示，我们将主要关注与Hibernate Named Query相关的组件。
hibernate.cfg.xml
<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE hibernate-configuration SYSTEM "http://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>
我们有一个hibernate映射文件，它只包含HQL命名查询和Native SQL命名查询。
named-queries.hbm.xml
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN""http://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>
query元素用于HQL命名查询，sql-query元素用于本机sql命名查询。我们可以使用return元素来声明结果集将映射到的实体。当我们连接多个表时使用return-join。
我们应该使用CDATA来声明我们的hibernate命名查询，以确保它被视为数据，否则<和> sings将搞乱我们的映射XML文件。
我们有两个模型类 - Employee和Address。我们在Address类中定义了名称查询，如下所示。
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@PrimaryKeyJoinColumnprivate 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;}@Overridepublic String toString() {return "AddressLine1= " + addressLine1 + ", City=" + city+ ", Zipcode=" + zipcode;}
}
让我们编写一个测试程序来使用上面定义的所有hibernate命名查询。
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) {// Prep workSessionFactory sessionFactory = HibernateUtil.getSessionFactory();Session session = sessionFactory.getCurrentSession();Transaction tx = session.beginTransaction();//HQL Named Query ExampleQuery query = session.getNamedQuery("HQL_GET_ALL_EMPLOYEE");List<Employee> 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<Address> addressList = query.list();for (Address addr : addressList) {System.out.println("List of Address::" + addr.getId() + "::"+ addr.getZipcode() + "::" + addr.getEmployee().getName());}//Native SQL Named Query Examplequery = session.getNamedQuery("@SQL_GET_ALL_ADDRESS");List<Object[]> 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);}// rolling back to save the test datatx.commit();// closing hibernate resourcessessionFactory.close();}}
当我们使用我们拥有的测试数据执行上述程序时，它会产生以下输出。
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
关于Hibernate命名查询的几点重要;
这就是Hibernate命名查询示例，您可以从下面的链接下载示例项目。
下载Hibernate命名查询项目
转载来源：https://www.journaldev.com/3451/hibernate-named-query-example-namedquery
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