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()
@JoinCol
11554
umn(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。