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Eclipse快速上手Hibernate--5. 关联映射(一对一)
摘要: Eclipse快速上手Hibernate--5. 关联映射(一对一)
1. 创建项目 · 新建一个Java项目：AssociationMapping，注意选中“创建单独的源文件夹和输出文件夹”，同时添加“用户库”：hibernate。
2. 编写类文件 · 新建一个类，包名：javamxj.hibernate.association.one2one，类名：Person。· 注意Person类的主键生成方式是“foreign”，使其参考Address类的主键。· 在最后几行中指明了如何引用Address类的方式，其中cascade="all" 表示所有情况下均进行级联操作。 · 这里将Address类独立映射为一个表。
Person.java
/*
* Hibernate - 关联(Association)映射
* 创建日期 2005-4-25
* @author javamxj（分享java快乐）
* @link Blog: htpp://blog.csdn.net/javamxj/
* htpp://javamxj.mblogger.cn
*/
package javamxj.hibernate.association.one2one;
/**
* @hibernate.class table = "T_Person"
*/
public class Person {
private Long id;
private String username;
private Address address;
/**
* @hibernate.id
* generator-class="foreign"
* @hibernate.generator-param
* name="property"
* value="address"
*/
public Long getId() {return id;}
public void setId(Long id) {this.id = id;}
/**
* @hibernate.property
* length="15"
* not-null="true"
*/
public String getUsername() {return username;}
public void setUsername(String username) {this.username = username;}
/**
* @hibernate.one-to-one
* cascade="all"
*/
public Address getAddress() {return address;}
public void setAddress(Address address) {this.address = address;}
}
Address.java
package javamxj.hibernate.association.one2one;
/**
* @hibernate.class table = "T_Address"
*/
public class Address {
private String country;
private String city;
private String street;
private String zipCode;
private Long id;
public Address() {}
public Address(String country, String city, String street, String zipcode) {
super();
this.country = country;
this.city = city;
this.street = street;
this.zipCode = zipcode;
}
/**
* @hibernate.id
*generator-class="hilo"
*unsaved-value="null"
*/
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
/**
* @hibernate.property
* length = "12"
*/
public String getCity() {return city;}
public void setCity(String city) {this.city = city;}
/**
* @hibernate.property
* length = "12"
*/
public String getCountry() {return country;}
public void setCountry(String country) {this.country = country;}
/**
* @hibernate.property
* length = "6"
*/
public String getZipCode() {return zipCode;}
public void setZipCode(String number) {this.zipCode = number;}
/**
* @hibernate.property
* length = "12"
*/
public String getStreet() {return street;}
public void setStreet(String street) {this.street = street;}
}3. 运行任务
· 复制《Eclipse快速上手Hibernate--4. 继承映射(1)》文中的build.xml到项目根目录下。
5. 另一种映射方式 这里简单说说一个外键和一个惟一关键字对应的方式。 以上面的文章为基础，只要改动一下Person.java即可。· 需要改动的部分用斜体字标出来了，有两处，一处是定义主键的生成方式，一处是Person类如何引用Address类。 · 看看Person类的映射文件中的相关部分：
· 双击“generate-hbm”任务，会发现在包中产生了Person.hbm.xml和Address.hbm.xml文件，在src目录下会多了一个hibernate.cfg.xml文件，如果没有，按F5键刷新一下。 · 看看Person类的映射文件中的重点部分：
address
import net.sf.hibernate.HibernateException; import net.sf.hibernate.Session; import net.sf.hibernate.SessionFactory; import net.sf.hibernate.Transaction; import net.sf.hibernate.cfg.Configuration; public class Demo { public static void main(String[] args) throws HibernateException { Address address1 = new Address("中国", "上海", "普陀", "200055"); Person p1 = new Person(); p1.setUsername("JavaMXJ"); p1.setAddress(address1); Address address2 = new Address("中国", "北京", "海淀", "100086"); Person p2 = new Person(); p2.setUsername("张三"); p2.setAddress(address2); SessionFactory sf = new Configuration().configure().buildSessionFactory(); Session sess = sf.openSession(); Transaction tx= sess.beginTransaction(); sess.save(p1); sess.save(p2); tx.commit(); sess.close(); sf.close(); } }
· 运行这个类，数据表中生成如下数据： 注意这两个表中的主键值相同的。 · 最后的项目结构如下： address
import net.sf.hibernate.HibernateException; import net.sf.hibernate.Session; import net.sf.hibernate.SessionFactory; import net.sf.hibernate.Transaction; import net.sf.hibernate.cfg.Configuration; public class Demo { public static void main(String[] args) throws HibernateException { Address address1 = new Address("中国", "上海", "普陀", "200055"); Person p1 = new Person(); p1.setUsername("JavaMXJ"); p1.setAddress(address1); Address address2 = new Address("中国", "北京", "海淀", "100086"); Person p2 = new Person(); p2.setUsername("张三"); p2.setAddress(address2); SessionFactory sf = new Configuration().configure().buildSessionFactory(); Session sess = sf.openSession(); Transaction tx= sess.beginTransaction(); sess.save(p1); sess.save(p2); tx.commit(); sess.close(); sf.close(); } }
5. 另一种映射方式 这里简单说说一个外键和一个惟一关键字对应的方式。 以上面的文章为基础，只要改动一下Person.java即可。
Person.java
/*
* Hibernate - 关联(Association)映射
* 创建日期 2005-4-25
* @author javamxj（分享java快乐）
* @link Blog: htpp://blog.csdn.net/javamxj/
* htpp://javamxj.mblogger.cn
*/
package javamxj.hibernate.association.one2one;
/**
* @hibernate.class table = "T_Person"
*/
public class Person {
private Long id;
private String username;
private Address address;
/**
* @hibernate.id
*generator-class="hilo"
*unsaved-value="null"
*/
public Long getId() {return id;}
public void setId(Long id) {this.id = id;}
/**
* @hibernate.property
* length="15"
* not-null="true"
*/
public String getUsername() {return username;}
public void setUsername(String username) {this.username = username;}
/**
* @hibernate.many-to-one
* column = "fk_Address"
* cascade="all"
* unique="true"
*/
public Address getAddress() {return address;}
public void setAddress(Address address) {this.address = address;}
}