一对一、一对多、多对多的配置

一对一

基于注解的方式：

 hibernate中一对一的关联有两种方式：一种是采用外键关联，另外一种是采用主键关联。

  一个丈夫(husband)对应一个妻子(wife)，主要目标是在存储丈夫或者妻子时，关联的对象也被存储。具体代码如下：

  husband类： 

package cn.edu.dlnu.resources.model.entity;

import javax.persistence.CascadeType;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.OneToOne;
import javax.persistence.PrimaryKeyJoinColumn;

@Entity
public class Husband {
 private int id;
 private String name;
 private Wife wife;
 @Id
 @GeneratedValue //主键生成器
 public int getId() {
  return id;
 }
 public String getName() {
  return name;
 }
 @OneToOne(cascade=CascadeType.ALL)
 @PrimaryKeyJoinColumn//这个注解只能写在主(生成ID)的一端
 public Wife getWife() {
  return wife;
 }
 public void setId(int id) {
  this.id = id;
 }
 public void setName(String name) {
  this.name = name;
 }
 public void setWife(Wife wife) {
  this.wife = wife;
 }
}
  wife类：

package cn.edu.dlnu.resources.model.entity;

import javax.persistence.CascadeType;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.OneToOne;
import org.hibernate.annotations.GenericGenerator;
import org.hibernate.annotations.Parameter;

@Entity
public class Wife {
 private int id;
 private String name;
 private Husband husband;
 
 @Id
 @GenericGenerator(name ="pkGenerator",strategy="foreign" ,parameters={@Parameter(name="property",value="husband")})
    @GeneratedValue(generator="pkGenerator")

//wife的ID是根据husband的ID来赋值的，这里需要设置ID生成器的策略为foreign，参数中指定wife的ID是使用husband对象中的ID
 public int getId() {
  return id;
 }
 public void setId(int id) {
  this.id = id;
 }
 public String getName() {
  return name;
 }
 public void setName(String name) {
  this.name = name;
 }
 public void setHusband(Husband husband) {
  this.husband = husband;
 }
 @OneToOne(cascade=CascadeType.ALL, mappedBy="wife")

 public Husband getHusband() {
  return husband;
 }
}
  OneToOnePKTest类：

package cn.edu.dlnu.resources.model.entity;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.AnnotationConfiguration;
import org.hibernate.tool.hbm2ddl.SchemaExport;
import org.junit.AfterClass;
import org.junit.BeforeClass;
import org.junit.Test;

import cn.edu.dlnu.resources.model.entity.Husband;
import cn.edu.dlnu.resources.model.entity.Wife;

public class OneToOnePKTest {
 private static SessionFactory sessionFactory;
 
 @BeforeClass
 public static void beforeClass() {
   sessionFactory = new AnnotationConfiguration().configure().buildSessionFactory();
 }
 @AfterClass
 public static void afterClass() {
  sessionFactory.close();
 }
 
 @Test
 public void testSave(){
  Session s = sessionFactory.getCurrentSession();
  s.beginTransaction();
  
  Husband h = new Husband();
  Wife w = new Wife();
  w.setName("w");
  h.setName("h");

  h.setWife(w);
  w.setHusband(h);
  s.save(w);
  s.getTransaction().commit();
 }

@Test
 public void testSchemaExport() {
  new SchemaExport(new AnnotationConfiguration().configure()).create(false, true);
 }
 public static void main(String[] args) {
  beforeClass();
  new OneToOnePKTest().testSave();
  afterClass();
 }
}

hibernate生成的数据库表：create table Husband (
        id integer not null auto_increment,
        name varchar(255),
        primary key (id)
    )；

create table Wife (
        id integer not null,
        name varchar(255),
        primary key (id)
    )
运行testSave()，方法后数据库中husband 与 wife表中记录的主键一致。