使用注解Hibernate一对一示例

在这里, 我们将使用注解按一对一的元素执行一对一的映射。在这种情况下, 不会在主表中创建任何外键。

在此示例中, 一个雇员可以有一个地址, 而一个地址仅属于一个雇员。在这里, 我们使用双向关联。让我们看一下持久化类。

1）一对一映射的持久类

有两个持久性类Employee.java和Address.java。雇员类包含地址类引用, 反之亦然。

Employee.java

package com.srcmini;
import javax.persistence.*;

@Entity
@Table(name="emp220")
public class Employee {  
	
	@Id
	@GeneratedValue(strategy=GenerationType.AUTO)
	@PrimaryKeyJoinColumn
private int employeeId;  
private String name, email;  
@OneToOne(targetEntity=Address.class, cascade=CascadeType.ALL)
private Address address;
public int getEmployeeId() {
	return employeeId;
}
public void setEmployeeId(int employeeId) {
	this.employeeId = employeeId;
}
public String getName() {
	return name;
}
public void setName(String name) {
	this.name = name;
}
public String getEmail() {
	return email;
}
public void setEmail(String email) {
	this.email = email;
}
public Address getAddress() {
	return address;
}
public void setAddress(Address address) {
	this.address = address;
}  

}

Address.java

package com.srcmini;
import javax.persistence.*;

@Entity
@Table(name="address220")
public class Address {  
	
	@Id
	@GeneratedValue(strategy=GenerationType.AUTO)
private int addressId;  
private String addressLine1, city, state, country;  
private int pincode;  

@OneToOne(targetEntity=Employee.class)
private Employee employee;
public int getAddressId() {
	return addressId;
}
public void setAddressId(int addressId) {
	this.addressId = addressId;
}
public String getAddressLine1() {
	return addressLine1;
}
public void setAddressLine1(String addressLine1) {
	this.addressLine1 = addressLine1;
}
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 getCountry() {
	return country;
}
public void setCountry(String country) {
	this.country = country;
}
public int getPincode() {
	return pincode;
}
public void setPincode(int pincode) {
	this.pincode = pincode;
}
public Employee getEmployee() {
	return employee;
}
public void setEmployee(Employee employee) {
	this.employee = employee;
}  
}

2）在pom.xml文件中添加项目信息和配置。

打开pom.xml文件, 然后单击源。现在, 在<dependencies> …. </ dependencies>标记之间添加以下依赖关系。这些依赖关系用于在Maven项目中添加jar文件。

<dependency>  
    <groupId>org.hibernate</groupId>  
    <artifactId>hibernate-core</artifactId>  
    <version>5.3.1.Final</version>  
</dependency>

<dependency>  
    <groupId>com.oracle</groupId>  
    <artifactId>ojdbc14</artifactId>  
    <version>10.2.0.4.0</version>  
</dependency>

3）配置文件

该文件包含有关数据库和映射文件的信息。

hibernate.cfg.xml

<?xml version='1.0' encoding='UTF-8'?>  
<!DOCTYPE hibernate-configuration PUBLIC  
          "-//Hibernate/Hibernate Configuration DTD 5.3//EN"  
          "http://hibernate.sourceforge.net/hibernate-configuration-5.3.dtd">  
   
<hibernate-configuration>  
  
    <session-factory>  
        <property name="hbm2ddl.auto">update</property>  
        <property name="dialect">org.hibernate.dialect.Oracle9Dialect</property>  
        <property name="connection.url">jdbc:oracle:thin:@localhost:1521:xe</property>  
        <property name="connection.username">system</property>  
        <property name="connection.password">jtp</property>  
        <property name="connection.driver_class">oracle.jdbc.driver.OracleDriver</property>  
    <mapping class="com.srcmini.Address"/>  
    <mapping class="com.srcmini.Employee"/>  
    </session-factory>  
  
</hibernate-configuration>

4）用于存储和获取数据的用户类

Store.java

package com.srcmini;  
  
import org.hibernate.*;
import org.hibernate.boot.Metadata;
import org.hibernate.boot.MetadataSources;
import org.hibernate.boot.registry.StandardServiceRegistry;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;  
  
public class Store {  
public static void main(String[] args) {  
    
	StandardServiceRegistry ssr=new StandardServiceRegistryBuilder().configure("hibernate.cfg.xml").build();
	Metadata meta=new MetadataSources(ssr).getMetadataBuilder().build();
	
	SessionFactory factory=meta.getSessionFactoryBuilder().build();
	Session session=factory.openSession();
	
    Transaction t=session.beginTransaction(); 
	
    Employee e1=new Employee();  
    e1.setName("Ravi Malik");  
    e1.setEmail("ravi@gmail.com");  
      
    Address address1=new Address();  
    address1.setAddressLine1("G-21, Lohia nagar");  
    address1.setCity("Ghaziabad");  
    address1.setState("UP");  
    address1.setCountry("India");  
    address1.setPincode(201301);  
      
    e1.setAddress(address1);  
    address1.setEmployee(e1);  
      
    session.persist(e1);  
    t.commit();  
      
    session.close();  
    System.out.println("success");  
}  
}

输出量

Fetch.java

package com.srcmini;  
import java.util.Iterator;  
import java.util.List;

import javax.persistence.TypedQuery;  
import org.hibernate.Session;  
import org.hibernate.SessionFactory;
import org.hibernate.boot.Metadata;
import org.hibernate.boot.MetadataSources;
import org.hibernate.boot.registry.StandardServiceRegistry;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder; 
  
public class Fetch {  
public static void main(String[] args) {  
	StandardServiceRegistry ssr=new StandardServiceRegistryBuilder().configure("hibernate.cfg.xml").build();
	Metadata meta=new MetadataSources(ssr).getMetadataBuilder().build();
	
	SessionFactory factory=meta.getSessionFactoryBuilder().build();
	Session session=factory.openSession();
      
    TypedQuery query=session.createQuery("from Employee");  
    List<Employee> list=query.getResultList(); 
      
    Iterator<Employee> itr=list.iterator();  
    while(itr.hasNext()){  
     Employee emp=itr.next();  
     System.out.println(emp.getEmployeeId()+" "+emp.getName()+" "+emp.getEmail());  
     Address address=emp.getAddress();  
     System.out.println(address.getAddressLine1()+" "+address.getCity()+" "+  
        address.getState()+" "+address.getCountry()+" "+address.getPincode());  
    }  
  
    session.close();  
    System.out.println("success");  
}  
}

输出量

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