(摘自互联网,备份)Hibernate实体关系:双向关联,mappedBy必设
注解方式
1、一对一单向
@Entity public class Husband{ @Id @GenerateValue pirvate int id; private String name; @OneToOne @JoinColumn(name="wifeId") private Wife wife; } @Entity public class Wife{ @Id @GenerateValue private int id; private String name; }
2.、一对一双向
@Entity public class Husband{ @Id @GenerateValue pirvate int id; private String name; @OneToOne @JoinColumn(name="wifeId") private Wife wife; } @Entity public class Wife{ @Id @GenerateValue private int id; private String name; @OneToOne(mappedBy="wife") private Husband husband; }
3.、一对多单向
package com.bjsxt.hibernate; import java.util.HashSet; import java.util.Set; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.Id; import javax.persistence.JoinColumn; import javax.persistence.OneToMany; import javax.persistence.Table; @Entity @Table(name="t_group") public class Group { private int id; private String name; private Set<User> users = new HashSet<User>(); @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; } @OneToMany @JoinColumn(name="groupId") //不加出现3张表 public Set<User> getUsers() { return users; } public void setUsers(Set<User> users) { this.users = users; } } package com.bjsxt.hibernate; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.Id; import javax.persistence.ManyToOne; import javax.persistence.Table; @Entity @Table(name="t_user") public class User { 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; } }
4、多对一单向
package com.bjsxt.hibernate; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.Id; import javax.persistence.Table; @Entity @Table(name="t_group") public class Group { 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; } } package com.bjsxt.hibernate; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.Id; import javax.persistence.ManyToOne; import javax.persistence.Table; @Entity @Table(name="t_user") public class User { private int id; private String name; private Group group; @ManyToOne public Group getGroup() { return group; } public void setGroup(Group group) { this.group = group; } @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; } }
5、一对多双向
package com.bjsxt.hibernate; import java.util.HashSet; import java.util.Set; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.Id; import javax.persistence.JoinColumn; import javax.persistence.OneToMany; import javax.persistence.Table; @Entity @Table(name="t_group") public class Group { private int id; private String name; private Set<User> users = new HashSet<User>(); @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; } @OneToMany(mappedBy="group") public Set<User> getUsers() { return users; } public void setUsers(Set<User> users) { this.users = users; } } package com.bjsxt.hibernate; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.Id; import javax.persistence.ManyToOne; import javax.persistence.Table; @Entity @Table(name="t_user") public class User { private int id; private String name; private Group group; @ManyToOne public Group getGroup() { return group; } public void setGroup(Group group) { this.group = group; } @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; } }
6、多对多单向
@Entity public class Student { 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; } } @Entity public class Teacher { private int id; private String name; private Set<Student> students = new HashSet<Student>(); @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; } @ManyToMany @JoinTable(name="t_s", joinColumns={@JoinColumn(name="teacher_id")}, inverseJoinColumns={@JoinColumn(name="student_id")} ) //改变中间表的名字和字段名字 public Set<Student> getStudents() { return students; } public void setStudents(Set<Student> students) { this.students = students; } }
7、多对多双向
@Entity public class Student { private int id; private String name; private Set<Teacher> teachers = new HashSet<Teacher>(); @ManyToMany(mappedBy="students") public Set<Teacher> getTeachers() { return teachers; } public void setTeachers(Set<Teacher> teachers) { this.teachers = teachers; } @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; } } @Entity public class Teacher { private int id; private String name; private Set<Student> students = new HashSet<Student>(); @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; } @ManyToMany @JoinTable(name="t_s", joinColumns={@JoinColumn(name="teacher_id")}, inverseJoinColumns={@JoinColumn(name="student_id")} ) public Set<Student> getStudents() { return students; } public void setStudents(Set<Student> students) { this.students = students; } }
XML配置
1、一对一单向
<class name="Person"> <id name="id" column="personId"> <generator class="native"/> </id> <many-to-one name="address" column="addressId" unique="true" not-null="true"/> </class> <class name="Address"> <id name="id" column="addressId"> <generator class="native"/> </id> </class>
2.、一对一双向
<class name="Person"> <id name="id" column="personId"> <generator class="native"/> </id> <many-to-one name="address" column="addressId" unique="true" not-null="true"/> </class> <class name="Address"> <id name="id" column="addressId"> <generator class="native"/> </id> <one-to-one name="person" property-ref="address"/> </class>
3.、一对多单向
<class name="Person"> <id name="id" column="personId"> <generator class="native"/> </id> <set name="addresses"> <key column="personId" not-null="true"/> <one-to-many class="Address"/> </set> </class> <class name="Address"> <id name="id" column="addressId"> <generator class="native"/> </id> </class>
4、多对一单向
<class name="Person"> <id name="id" column="personId"> <generator class="native"/> </id> <many-to-one name="address" column="addressId" not-null="true"/> </class> <class name="Address"> <id name="id" column="addressId"> <generator class="native"/> </id> </class>
5、一对多双向
<hibernate-mapping> <class name="com.bjsxt.hibernate.Group" table="t_group"> <id name="id"> <generator class="native"></generator> </id> <property name="name"></property> <set name="users" inverse=”true”> <key column="groupId"></key> //与<many-to-one>的column一致 <one-to-many class="com.bjsxt.hibernate.User"/> </set> </class> </hibernate-mapping> <hibernate-mapping> <class name="com.bjsxt.hibernate.User" table="t_user"> <id name="id"> <generator class="native"></generator> </id> <property name="name"></property> <many-to-one name="group" column="groupId"></many-to-one> </class> </hibernate-mapping>
6、多对多单向
<hibernate-mapping> <class name="com.bjsxt.hibernate.Student"> <id name="id"> <generator class="native"></generator> </id> <property name="name"></property> </class> </hibernate-mapping> <hibernate-mapping> <class name="com.bjsxt.hibernate.Teacher"> <id name="id"> <generator class="native"></generator> </id> <property name="name"></property> <set name="students" table="t_s"> <key column="teacher_id"></key> <many-to-many class="com.bjsxt.hibernate.Student" column="student_id"/> </set> </class> </hibernate-mapping>
7、多对多双向
<hibernate-mapping> <class name="com.bjsxt.hibernate.Student"> <id name="id"> <generator class="native"></generator> </id> <property name="name"></property> <set name="teachers" table="t_s" inverse=”true”> <key column="student_id"></key> <many-to-many class="com.bjsxt.hibernate.Teacher" column="teacher_id"/> </set> </class> </hibernate-mapping> <hibernate-mapping> <class name="com.bjsxt.hibernate.Teacher"> <id name="id"> <generator class="native"></generator> </id> <property name="name"></property> <set name="students" table="t_s"> <key column="teacher_id"></key> <many-to-many class="com.bjsxt.hibernate.Student" column="student_id"/> </set> </class> </hibernate-mapping>