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📜  使用注释休眠一对一示例

📅  最后修改于: 2021-01-02 15:44:10             🧑  作者: Mango

使用注释休眠一对一示例

在这里，我们将使用注释按一对一元素执行一对一映射。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。让我们看一下持久性类。

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.javatpoint;
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;
}  

}

地址.java

package com.javatpoint;
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 …. 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。

  
    org.hibernate  
    hibernate-core  
    5.3.1.Final  
  

  
    com.oracle  
    ojdbc14  
    10.2.0.4.0

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

  
  
   
  
  
      
        update  
        org.hibernate.dialect.Oracle9Dialect  
        jdbc:oracle:thin:@localhost:1521:xe  
        system  
        jtp  
        oracle.jdbc.driver.OracleDriver

4)用于存储和获取数据的用户类

Store.java

package com.javatpoint;  
  
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


获取.java

package com.javatpoint;  
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 list=query.getResultList(); 
      
    Iterator 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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