1.数据库：oracle数据库，有person和address二张表，一对多的关系。
create table person
(
id number(4) not null,
uname varchar (20)
);
create table address
(
id number(4) not null,
address varchar(20) not null,
personId number(4) not null
)
alter table person
add constraint primary_id parmary key(id)
deferrable initially deferred;
数据库 2.Person实体类：
package com.zengguo.po;
import java.io.Serializable;
import java.util.HashSet;
import java.util.Set;
import javax.persistence.CascadeType;
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;
import org.hibernate.annotations.Fetch;
import org.hibernate.annotations.FetchMode;
import org.hibernate.annotations.GenericGenerator;
import org.hibernate.annotations.Parameter;
@SuppressWarnings(“serial”)
@Entity
@Table(name = “person”)
public class Person implements Serializable {
//oracle 序列
@Id
@GenericGenerator(name = “personGenericGenerator”, strategy = “sequence”,
parameters = { @Parameter(value = “hibernate_seq”, name = “sequence”) })
@GeneratedValue(generator=”personGenericGenerator”)
private long id;
@Column(name=”uname”)
private String uname;
@OneToMany(targetEntity=Address.class,cascade=CascadeType.ALL)
@Fetch(FetchMode.JOIN)
//updatable=false很关键，如果没有它，在级联删除的时候就会报错(反转的问题)
@JoinColumn(name=”personId”,updatable=false)
private Set
sets = new HashSet ();public Set
getSets() {return sets;
}
public void setSets(Set
sets) {this.sets = sets;
}
public Person() {
super();
}
public long getId() {
return id;
}
public void setId(long id) {
this.id = id;
}
public String getUname() {
return uname;
}
public void setUname(String uname) {
this.uname = uname;
}
}
3.Address实体类
package com.zengguo.po;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.Table;
import org.hibernate.annotations.GenericGenerator;
import org.hibernate.annotations.Parameter;
@SuppressWarnings(“serial”)
@Entity
@Table(name = “address”)
public class Address implements java.io.Serializable {
//使用序列生成主键
@Id
@GenericGenerator(name = “addressGenericGenerator”, strategy = “sequence”,
parameters = { @Parameter(value = “hibernate_seq”, name = “sequence”) })
@GeneratedValue(generator = “addressGenericGenerator”)
private long id;
@Column(name = “address”)
private String address;
//多对一，@JoinColumn与@column类似，指定映射的数据库字段
@ManyToOne(targetEntity = Person.class)
@JoinColumn(name=”personId”,updatable=false)
private Person person;
public Address() {
super();
}
public long getId() {
return id;
}
public void setId(long id) {
this.id = id;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
public Person getPerson() {
return person;
}
public void setPerson(Person person) {
this.person = person;
}
}
