Hibernate复习-关系映射
在公司好久不用hibernate了，怕hibernate忘记了，算是写个笔记等用的时候来查询
- hibernate配置
这个主要参考hibernate的doc文档就行 有一个hibernate.cfg.xml文件，然后在配置一个hibernateUtil工具获得sessionFactory就行
而且今后使用全部用注解，xml配置忽略了，像hdm.xml这种文件也不学习了
一对一
一对一单向
Person类
package com.hfview.bean;
import javax.persistence.*;
import org.hibernate.annotations.ForeignKey;
/** * 单个的人 * @author zhw * */
@Entity
@Table(name="T_Person")
public class Person {
public int id;
public String name;
public String psw;
private Card card;
@OneToOne()
@JoinColumn(name="cardId")//指定数据库里面card在peron表里面的名字
public Card getCard() {
return card;
}
public void setCard(Card card) {
this.card = card;
}
@Id
@GeneratedValue
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 String getPsw() {
return psw;
}
public void setPsw(String psw) {
this.psw = psw;
}
}
身份证类
package com.hfview.bean;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Table;
/** * 人的身份证号码 * @author zhw * */
@Entity
@Table(name="T_Card")
public class Card {
private int id;
private String cardNum;
@Id
@GeneratedValue
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getCardNum() {
return cardNum;
}
public void setCardNum(String cardNum) {
this.cardNum = cardNum;
}
}
生成的sql语句
- create table T_Card (
id int identity not null,
cardNum varchar(255) null,
primary key (id)
)
create table T_Person (
id int identity not null,
name varchar(255) null,
psw varchar(255) null,
cardId int null,
primary key (id)
)
alter table T_Person
add constraint FK459B3DC0AC77181B
foreign key (cardId)
references T_Card
一对一双向映射
Person类还是上面的那个，但是card类做出改变
package com.hfview.bean;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.OneToOne;
import javax.persistence.Table;
/** * 人的身份证号码 * @author zhw * */
@Entity
@Table(name="T_Card")
public class Card {
private int id;
private String cardNum;
private Person person;
//这里如果不写mappedBy，那么会在card里面生成一个指向person的外键
//这句话就是指映射是在person类中 card(具体是getXXX的xxx部分)字段完成，这里的映射hibernate就不要关了
@OneToOne(mappedBy="card")
public Person getPerson() {
return person;
}
public void setPerson(Person person) {
this.person = person;
}
@Id
@GeneratedValue
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getCardNum() {
return cardNum;
}
public void setCardNum(String cardNum) {
this.cardNum = cardNum;
}
}
这里和上一个生成的建表sql是一样的
组件映射
person类
package com.hfview.bean;
import javax.persistence.*;
import org.hibernate.annotations.ForeignKey;
/** * 单个的人 * @author zhw * */
@Entity
@Table(name="T_Person")
public class Person {
public int id;
public String name;
public String psw;
private Card card;
@Embedded //可写可不写
private Country country;
public Country getCountry() {
return country;
}
public void setCountry(Country country) {
this.country = country;
}
@OneToOne()
@JoinColumn(name="cardId")
public Card getCard() {
return card;
}
public void setCard(Card card) {
this.card = card;
}
@Id
@GeneratedValue
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 String getPsw() {
return psw;
}
public void setPsw(String psw) {
this.psw = psw;
}
}
country类
package com.hfview.bean;
import javax.persistence.Column;
import javax.persistence.Embeddable;
@Embeddable
public class Country {
private int age;
private String name;
@Column(name="countryAge")
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
@Column(name="countryName")
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
特别需要注意的是如果country里面的age、name不使用column来指定名字的话，那么就会和person里面的重合，在数据库里面就会忽略country的age和name
另外一种指定名字的方式是：
@Embedded
//@AttributeOverrides并不是官网中的放在这里，放在这里不起作用
private Country country;
@AttributeOverrides( {
@AttributeOverride(name="age", column = @Column(name="countryAge2") ),
@AttributeOverride(name="name", column = @Column(name="countryName2") )
} )
public Country getCountry() {
return country;
}多对一
Flight 航班类
package com.hfview.bean;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
@Entity
public class Flight {
private int id;
private String name;
private Company company;
@ManyToOne
@JoinColumn(name="companyId")//这里指定所属公司的字段名
public Company getCompany() {
return company;
}
@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 setCompany(Company company) {
this.company = company;
}
}
航空公司类Company
package com.hfview.bean;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
@Entity
public class Company {
private int id;
private String name;
@Id @GeneratedValue
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;
}
}
一对多
一对多中，必须用集合保存多的那一方
比如 城市类
package com.hfview.bean;
import java.util.Set;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.OneToMany;
@Entity
public class City {
private int id;
private String name;
private Set<Street> street;
@OneToMany
@JoinColumn(name="cityId")
public Set<Street> getStreet() {
return street;
}
public void setStreet(Set<Street> street) {
this.street = street;
}
@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;
}
}
街道类
package com.hfview.bean;
import javax.persistence.Entity;
import javax.persistence.Id;
@Entity
public class Street {
private int id;
private String name;
@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;
}
}
这里必须要注意，如果city中的属性 街道 那里没有设置@joinCoulmn那么，hibernate将会生成三张表，类似于多对多来处理
一对多和多对一双向关联
city类
package com.hfview.bean;
import java.util.Set;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.OneToMany;
@Entity
public class City {
private int id;
private String name;
private Set<Street> street;
@OneToMany(mappedBy="city")
public Set<Street> getStreet() {
return street;
}
public void setStreet(Set<Street> street) {
this.street = street;
}
@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;
}
}
街道类
package com.hfview.bean;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
@Entity
public class Street {
private int id;
private String name;
private City city;
@ManyToOne
@JoinColumn(name="cityId")
public City getCity() {
return city;
}
public void setCity(City city) {
this.city = city;
}
@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;
}
}
这里一定要注意，双向关联一定要设置mappedBy，设计数据库的时候就是在多的那一方加上属于一的那个字段就行，这个时候多的那方（street）就是主导，mappedBy要写在一的那方（city）
多对多单向
Boss类
package com.hfview.bean;
import java.util.Set;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.ManyToMany;
@Entity
public class Boss {
private int id;
private String name;
@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;
}
}
员工类
package com.hfview.bean;
import java.util.Set;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.JoinTable;
import javax.persistence.ManyToMany;
@Entity
public class Employee {
private int id;
private String name;
private Set<Boss> boss;
@ManyToMany
@JoinTable(
name="Employee_Boss",
joinColumns=@JoinColumn(name="employeeId", referencedColumnName="id"),
inverseJoinColumns=@JoinColumn(name="bossId", referencedColumnName="id")
)//修改中间表的字段
public Set<Boss> getBoss() {
return boss;
}
public void setBoss(Set<Boss> boss) {
this.boss = boss;
}
@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;
}
}
多对多双向
Boss类
package com.hfview.bean;
import java.util.Set;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.ManyToMany;
@Entity
public class Boss {
private int id;
private String name;
private Set<Employee> employee;
@ManyToMany(mappedBy="boss")
public Set<Employee> getEmployee() {
return employee;
}
public void setEmployee(Set<Employee> employee) {
this.employee = employee;
}
@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;
}
}
Employee 类
package com.hfview.bean;
import java.util.Set;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.JoinTable;
import javax.persistence.ManyToMany;
@Entity
public class Employee {
private int id;
private String name;
private Set<Boss> boss;
@ManyToMany
@JoinTable(
name="Employee_Boss",
joinColumns=@JoinColumn(name="employeeId", referencedColumnName="id"),
inverseJoinColumns=@JoinColumn(name="bossId", referencedColumnName="id")
)
public Set<Boss> getBoss() {
return boss;
}
public void setBoss(Set<Boss> boss) {
this.boss = boss;
}
@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;
}
}
集合映射
这部分不需要记了，大部分用set，需要排序用list。
map更麻烦。