hibernate多對多關聯

多對多雙向關聯：一個老師可以教很多學生，一個學生也可以被很多老師教。這是多對多。

@Entity
public class Teacher {
    private int id;
    private String name;
    private Set<Student>stu=new HashSet<Student>();
    @Id
    @GeneratedValue
    public int getId() {
        return id;
    }

    @ManyToMany//多對多 默認情況下，hibernate會自動的創建一張中間表來維護多對多關係
    /*
     *  默認中間表的名稱 ：Teacher_Student中間表，字段的名稱Teacher_id stu_id,如果想更換表名和字段名稱，註解如下：
        @JoinTable
        (name="teacher_stu",中間表的名稱
        joinColumns={@JoinColumn(name="teacher_Id")},字段的名稱teacher_Id
        inverseJoinColumns={@JoinColumn(name="stu_Id")})字段的名稱stu_Id
     */
   @JoinTable(
    name="teacher_stu",
    joinColumns={@JoinColumn(name="teacher_Id")},
    inverseJoinColumns={@JoinColumn(name="stu_Id")}
   )
    public Set<Student> getStu() {
        return stu;
    }


}
@Entity
public class Student {
    private int id;
    private String name;
     private Set<Teacher>teacher=new HashSet<Teacher>();
    @Id
    @GeneratedValue
    public int getId() {
        return id;
    }
 //從一對一雙，到多對一雙向，到多對多雙向，mappedBy都要添加。 
        @ManyToMany(mappedBy="stu")      
    public Set<Teacher> getTeacher() {
        return teacher;
    }

}

多對多單向關聯：

@Entity
public class Teacher {
    private int id;
    private String name;
    private Set<Student>stu=new HashSet<Student>();
    @Id
    @GeneratedValue
    public int getId() {
        return id;
    }

    @ManyToMany//多對多 默認情況下，hibernate會自動的創建一張中間表來維護多對多關係
    /*
     *  默認中間表的名稱 ：Teacher_Student中間表，字段的名稱Teacher_id stu_id,如果想更換表名和字段名稱，註解如下：
        @JoinTable
        (name="teacher_stu",中間表的名稱
        joinColumns={@JoinColumn(name="teacher_Id")},字段的名稱teacher_Id
        inverseJoinColumns={@JoinColumn(name="stu_Id")})字段的名稱stu_Id
     */
   @JoinTable(
    name="teacher_stu",
    joinColumns={@JoinColumn(name="teacher_Id")},
    inverseJoinColumns={@JoinColumn(name="stu_Id")}
   )
    public Set<Student> getStu() {
        return stu;
    }


}
@Entity
public class Student {
    private int id;
    private String name;
    @Id
    @GeneratedValue
    public int getId() {
        return id;
    }

}