Hibernate表关联配置

一对一

一对一主键关联

1.XML配置

  • 必须双向关联
  • 被关联方主键生成策略为外键生成策略
  • 被关联方one-to-one需设置constrained=“true”约束
<!--Person表映射-->
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="com.kaishengit.pojo">
    <class name="Person" table="person">
        <id column="id" name="id">
           <generator class="native"/>
        </id>
        <property name="personName" column="person_name"/>
        <one-to-one name="card" cascade="all"/>
    </class>
</hibernate-mapping>
<!--Card表映射-->
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="com.kaishengit.pojo">
    <class name="Card" table="card">
        <id column="id" name="id">
            <generator class="foreign">
                <param name="property">person</param>
            </generator>
        </id>
        <property name="cardNum" column="card_num"/>
        <one-to-one name="person" constrained="true"/>
    </class>
</hibernate-mapping>

2.Java注解配置

  • 主控方使用@PrimaryKeyJoinColumn
  • 被控方在@OneToOne中要加上(mappedBy = "card")
//基于注解的配置
@Entity
@Table(name = "person")
public class Person {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Integer id;

    @Column(name = "person_name")
    private String personName;

    //共享主键关联使用PrimaryKeyJoinColumn
    @OneToOne(cascade = CascadeType.ALL)
    @PrimaryKeyJoinColumn
    private Card card;
  }

@Entity
@Table(name = "card")
public class Card {
    @Id
    @GenericGenerator(name = "generator",strategy = "foreign",
            parameters = @org.hibernate.annotations.Parameter(name = "property",value = "person"))
    @GeneratedValue(generator = "generator")
    private Integer id;

    @Column(name = "card_num")
    private String cardNum;


    //必须设置OneToOne,mappedBy为自己在对方中的属性名
    @OneToOne(mappedBy = "card")
    private Person person;
  }

一对一外键关联

数据库结构


数据库结构

1.XML配置

  • 各自主键生成策略无外键约束
  • 主控方(含外键的一方)使用many-to-one,并且要加上unique="true"约束
  • 被控方使用one-to-one,并且要加上property-ref="passageContent"
<!--Passage表-->
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="com.kaishengit.pojo">
    <class name="Passage" table="passage">
        <id name="id" column="id">
            <generator class="native"/>
        </id>
        <property name="title" column="title"/>
        <many-to-one name="passageContent" column="content_id" class="PassageContent" unique="true"/>
    </class>
</hibernate-mapping>
<!--PassageContent表-->
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="com.kaishengit.pojo">
    <class name="PassageContent" table="passage_content">
        <id name="id" column="id">
            <generator class="native"/>
        </id>
        <property name="content" column="content"/>
        <one-to-one name="passage" class="Passage" property-ref="passageContent"/>
    </class>
</hibernate-mapping>

2.Java注解配置

  • 区别于XML配置，这里全部采用@OneToOne
  • 主控方使用@JoinColumn(name = "content_id")
  • 被控方使用@OneToOne(mappedBy = "passageContent"),mappedBy相当于XML中的property-ref,是一个反向声明
@Entity
@Table(name = "passage")
public class Passage {

    @Id
    @GeneratedValue
    private Integer id;
    private String title;

    @OneToOne
    @JoinColumn(name = "content_id")
    private PassageContent passageContent;
  }

@Entity
@Table(name = "passage_content")
public class PassageContent {

    @Id
    @GeneratedValue
    private Integer id;
    private String content;


    @OneToOne(mappedBy = "passageContent")
    private Passage passage;
  }

一对多关联

  • 保存时先保存一端，再保存多端
    数据库结构


    一对多关联

    1.XML配置

  • 一端在set中要指明表及关联的键(即table和key属性),并且要放弃关系维护
<!--Address表-->
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="com.kaishengit.pojo">
    <class name="Address" table="address">
        <id name="id" column="id">
            <generator class="native"/>
        </id>


        <property name="cityName" column="city_name"/>
        <property name="address" column="address"/>
        <!--
            多对一
            name: 属性名称
            class: 属性的类型
            column: 外键的名称
            lazy: false表示关闭延时加载
            fetch: join 使用连接查询对象
        -->
        <many-to-one name="user" class="User" column="user_id" lazy="false" fetch="join"></many-to-one>
    </class>
</hibernate-mapping>
<!--User表-->
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="com.kaishengit.pojo">
    <class name="User" table="user">
        <cache usage="read-only"/>
        <id name="id" column="id">
            <generator class="native"/>
        </id>


        <property name="username" column="username"/>
        <set name="addressSet" table="address" cascade="delete" inverse="true">
            <key column="user_id"></key>
            <one-to-many class="Address"></one-to-many>
        </set>
    </class>
</hibernate-mapping>

2.Java注解配置

  • ManyToOne端要加上JoinColumn,OneToMany要加上mappedBy
  • 如需级联操作，一端还需加上Cascade
@Entity
@Table
public class Address {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Integer id;

    @Column(name = "city_name")
    private String cityName;
    private String address;

    @ManyToOne
    @JoinColumn(name = "user_id")
    private User user;
  }

@Entity
@Table
public class User {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Integer id;
    private String username;

    @OneToMany(mappedBy = "user")
    @Cascade(CascadeType.DELETE)
    private Set<Address> addressSet;
  }

多对多关联

数据库结构


多对对关联

1.XML配置

<!--Student表-->
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="com.kaishengit.pojo">
    <class name="Student" table="student">
        <id name="id" column="id">
            <generator class="native"/>
        </id>
        <property name="studentName" column="student_name"/>

        <set name="teacherSet" table="student_teacher_real">
            <key column="student_id"></key>
            <many-to-many class="Teacher" column="teacher_id"/>
        </set>
    </class>
</hibernate-mapping>
<!--Teacher表-->
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="com.kaishengit.pojo">
    <class name="Teacher" table="teacher">
        <id name="id" column="id">
            <generator class="native"/>
        </id>
        <property name="teacherName" column="teacher_name"/>

        <set name="studentSet" table="student_teacher_real" inverse="true">
            <key column="teacher_id"></key>
            <many-to-many class="Student" column="student_id"/>
        </set>
    </class>
</hibernate-mapping>

2.Java注解配置

@Entity
@Table
public class Student {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Integer id;



    @Column(name = "student_name")
    private String studentName;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    @ManyToMany
    @JoinTable(name = "student_teacher_real",joinColumns = {@JoinColumn(name = "student_id")},inverseJoinColumns = {@JoinColumn(name = "teacher_id")})
    private Set<Teacher> teacherSet;
  }

@Entity
@Table
public class Teacher {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Integer id;

    @Column(name = "teacher_name")
    private String teacherName;

    @ManyToMany(mappedBy = "teacherSet")
    private Set<Student> studentSet;
  }

Java注解总结

  • 如果是主键关联，那么就使用@PrimaryKeyJoinColumn,只要声明@JoinColumn,@PrimaryKeyJoinColumn,@JoinTable的都属于主控方，外键通常也就存储在主控方，对应的含有mappedBy的都为被控方。
  • 一对一关联不管是主键关联还是外键关联，基于注解都是OneToOne

XML配置总结

  • 一对一主键关联时，由于被控方的主键是主控方的外键，所以被控方的OneToOne标签中需要加constrained="true"约束
  • 被控方通常需要设置inverse="true"放弃关系维护
  • <one-to-many><many-to-many>这样的标签放置在<set>集合内部
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