Hibernate 使用 Annotation 之 OneToMany(单向关联关系)

Java代码如下：

package com.lwp.hibernate.Model;

import java.io.Serializable;
import java.util.HashSet;
import java.util.Set;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.OneToMany;
import javax.persistence.Table;

@Entity
@Table
public class Customer implements Serializable{

private static final long serialVersionUID = 1L;

public Customer(){}
public Customer(String name,Set<Order> orders){
this.name=name;
this.orders = orders;
}

@Id
@GeneratedValue
@Column(name="ID")
private Long id;

@Column(name="NAME",length=15)
private String name;

@OneToMany
@JoinColumn(name="customer_id")
private Set<Order> orders = new HashSet<Order>();

public Set<Order> getOrders() {
return orders;
}
public void setOrders(Set<Order> orders) {
this.orders = orders;
}
public Long getId() {
return id;
}

public void setId(Long id) {
this.id = id;
}

public String getName() {
return name;
}

public void setName(String name) {
this.name = name;
}
}

package com.lwp.hibernate.Model;

import java.io.Serializable;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name="ORDERS")
public class Order implements Serializable{

private static final long serialVersionUID = 1L;
public Order(){}

public Order(String orderNumber){
this.orderNumber =orderNumber;
}
@Id
@GeneratedValue
@Column(name="ID")
private Long id;

@Column(name="ORDER_NUMBER",length=15)
private String orderNumber;

public Long getId() {
return id;
}

public void setId(Long id) {
this.id = id;
}

public String getOrderNumber() {
return orderNumber;
}

public void setOrderNumber(String orderNumber) {
this.orderNumber = orderNumber;
}
}

import java.util.HashSet;
import java.util.Set;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.AnnotationConfiguration;
import org.hibernate.cfg.Configuration;
import org.hibernate.tool.hbm2ddl.SchemaExport;

import com.lwp.hibernate.Model.Customer;
import com.lwp.hibernate.Model.Order;

public class CustomerTest {

public static void main(String[] args) {
new SchemaExport(new AnnotationConfiguration().configure("/hibernate.cfg.xml")).create(true, false);

Set<Order> orders =  new HashSet<Order>();
Order order1 = new Order("Tom_Order001");
Order order2 = new Order("Tom_Order002");
orders.add(order1);
orders.add(order2);
Customer customer = new Customer("Tom",orders);
save(order1);
save(order2);
save(customer);
}

public static void save(Object o){
//Configuration cfg = new Configuration();//xx.hbm.xml形式下的new
Configuration cfg = new AnnotationConfiguration(); //Annotation形式下的new
SessionFactory sf = cfg.configure().buildSessionFactory();
Session session = sf.openSession();
session.beginTransaction();
session.save(o);
session.getTransaction().commit();
session.close();
sf.close();
}
}

SQL：

alter table ORDERS drop foreign key FK8B7256E5C1E4F651

drop table if exists Customer

drop table if exists ORDERS

create table Customer (ID bigint not null auto_increment, NAME varchar(15), primary key (ID))

create table ORDERS (ID bigint not null auto_increment, ORDER_NUMBER varchar(15), customer_id bigint, primary key (ID))

alter table ORDERS add index FK8B7256E5C1E4F651 (customer_id), add constraint FK8B7256E5C1E4F651 foreign key (customer_id) references Customer (ID)

Hibernate: insert into ORDERS (ORDER_NUMBER) values (?)

Hibernate: insert into ORDERS (ORDER_NUMBER) values (?)

Hibernate: insert into Customer (NAME) values (?)

Hibernate: update ORDERS set customer_id=? where ID=?

Hibernate: update ORDERS set customer_id=? where ID=?