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使用注释Hibernate多对一映射

在多对一映射中，各种属性只能引用一个属性。

在本例中，每个员工只有一个公司地址，一个地址属于多个员工。这里，我们将使用注释执行多对一映射。

让我们看一下持久化类

1)用于一对一映射的持久类

有两个持久化类Employee.java和Address.java。Employee类包含Address类引用，反之亦然。

Employee.java

            包com.javatpoint;进口javax.persistence。*;@Entity @Table(name="emp107") public class Employee {@Id @GeneratedValue(strategy=GenerationType.AUTO) private int employeeId;私人字符串名称，电子邮件;@ManyToOne(cascade=CascadeType.ALL) private Address地址;public int gettemployeeid(){返回employeeId;}公共无效setEmployeeId(int employeeId){这。employeeId = employeeId;}公共字符串getName(){返回名称;}公共无效setName(字符串名称){this.name =名称;}公共字符串getEmail(){返回电子邮件; } public void setEmail(String email) { this.email = email; } public Address getAddress() { return address; } public void setAddress(Address address) { this.address = address; } }
           

Address.java

            包com.javatpoint;进口javax.persistence。*;@Entity @Table(name="address107") public class Address {@Id @GeneratedValue(strategy=GenerationType.AUTO) private int addressId;私有字符串addressLine1，城市，州，国家;Private int pincode;@OneToOne(cascade=CascadeType.ALL) private Employee Employee;public int getAddressId(){返回addressId;}公共无效setAddressId(int addressId){这。addressId = addressId;}公共字符串getAddressLine1(){返回addressLine1;}公共无效setAddressLine1(String addressLine1){这。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文件并单击source。现在，在....之间添加以下依赖项< /依赖>标记。这些依赖关系用于在Maven项目中添加jar文件。

            <依赖> < groupId > org。hibernate</groupId> <artifactId>hibernate-core</artifactId> <version>5.3.1。最终版本> < / > < /依赖
           

            <依赖> < 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版本='1.0'编码='UTF-8'?> < !DOCTYPE Hibernate - Configuration PUBLIC "-//Hibernate/Hibernate配置DTD 5.3//EN" "http://hibernate.sourceforge.net/hibernate-configuration-5.3.dtd"> < Hibernate - Configuration > <session-factory> <property name="hbm2ddl. htm "。Auto ">create</property> <property name="dialect">org.hibernate.dialect。Oracle9Dialect</property> <property name="connection. "jdbc:oracle:thin:@localhost:1521:xe</property> <property name="connection. url">用户名">system</property> <property name="connection "。密码">jtp</property> <property name="connection.driver_class">oracle.jdbc.driver。OracleDriver</property> <mapping class="com.javatpoint. net . "地址"/> <mapping class="com.javatpoint。Employee"/> </session-factory> </hibernate-configuration>
           

4)存储和获取数据的用户类

Store.java

            包com.javatpoint;进口org.hibernate。*;进口org.hibernate.boot.Metadata;进口org.hibernate.boot.MetadataSources;进口org.hibernate.boot.registry.StandardServiceRegistry;进口org.hibernate.boot.registry.StandardServiceRegistryBuilder;public class Store {public static void main(String[] args) {StandardServiceRegistryBuilder().configure("hibernate.cfg.xml").build();元数据meta=new MetadataSources(ssr). getmetadatbuilder ().build();.build SessionFactory工厂= meta.getSessionFactoryBuilder () ();会议会话= factory.openSession (); Transaction t=session.beginTransaction(); Employee e1=new Employee(); e1.setName("Ravi Malik"); e1.setEmail("ravi@gmail.com"); Employee e2=new Employee(); e2.setName("Anuj Verma"); e2.setEmail("anuj@gmail.com"); Address address1=new Address(); address1.setAddressLine1("G-13,Sector 3"); address1.setCity("Noida"); address1.setState("UP"); address1.setCountry("India"); address1.setPincode(201301); e1.setAddress(address1); e2.setAddress(address1); session.persist(e1); session.persist(e2); t.commit(); session.close(); System.out.println("success"); } }
           

输出

Fetch.java

            包com.javatpoint;进口java.util.Iterator;进口并不知道;进口javax.persistence.TypedQuery;进口org.hibernate.Session;进口org.hibernate.SessionFactory;进口org.hibernate.boot.Metadata;进口org.hibernate.boot.MetadataSources;进口org.hibernate.boot.registry.StandardServiceRegistry;进口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 e"); 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"); } }
           