Hibernate多对多简单配置

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@Entity@Table(name="teacher",catalog="hibernate3")public class Teacher implements Serializable {private Long tid;private String name;private Integer age;private Set<Course> courses=new HashSet<>();     public Teacher() {super();}public Teacher( String name, Integer age) {super();this.name = name;this.age = age;}@Id@GeneratedValue(strategy=GenerationType.AUTO)    public Long getTid() {return tid;}public void setTid(Long tid) {this.tid = tid;}@Column(name="name",length=30)public String getName() {return name;}public void setName(String name) {this.name = name;}@Column(name="age",length=4)public Integer getAge() {return age;}public void setAge(Integer age) {this.age = age;}    /*    * @JoinTable配置一个中间表    * joinColumns:当前类在中间表的id列名    * inverseJoinColumns:对方类在中间表的id列名    */    @ManyToMany(cascade=CascadeType.ALL)    @JoinTable(name="thacher_course",    joinColumns=@JoinColumn(name="teacher_id"),    inverseJoinColumns={@JoinColumn(name="course_id")})public Set<Course> getCourses() {return courses;}public void setCourses(Set<Course> courses) {this.courses = courses;}}

Course类

@Entity@Table(name="course",catalog="hibernate3")public class Course implements Serializable {private Long cid;private String name;private Set<Teacher> teachers =new HashSet<>();    public Course(String name) {super();this.name = name;}public Course() {super();}@Id       @GeneratedValue  //默认AUTO--Native  public Long getCid() {return cid;}public void setCid(Long cid) {this.cid = cid;}@Column(name="name",length=20)public String getName() {return name;}  public void setName(String name) {this.name = name;} /* * mappedBy="courses"，表示自已不维护id关系了，交给对方Thacher去维护 */@ManyToMany(cascade=CascadeType.ALL,fetch=FetchType.LAZY,mappedBy="courses")//抓取策略@Fetch(FetchMode.SELECT)public Set<Teacher> getTeachers() {return teachers;}public void setTeachers(Set<Teacher> teachers) {this.teachers = teachers;}}

测试：双方最好要有

cascade=CascadeType.ALL

public class ManyToMany {   //课程添加老师@Testpublic void testName1() throws Exception {       Session session = HibernateUtils1.openSession();       Transaction trans = session.beginTransaction();       Teacher tt=new Teacher("zz11", 12);              Course cc1=new Course("语文111");             Set<Teacher> set=new HashSet<>();       set.add(tt);       //这里是课程添加老师，因为课程这边不维护关系，所以中间表没有记录的           cc1.setTeachers(set);              session.save(cc1);       trans.commit();       session.close();}//老师添加课程@Testpublic void testName111() throws Exception {Session session = HibernateUtils1.openSession();Transaction trans = session.beginTransaction();Teacher tt=new Teacher("aa1", 12);Course cc1=new Course("奥数1");Set<Course> set=new HashSet<>();set.add(cc1);//老师添加课程，老师需要维护关系（写入中间表）tt.setCourses(set);   session.save(tt);trans.commit();session.close();}@Testpublic void testName3() throws Exception {Session session = HibernateUtils1.openSession();Transaction trans = session.beginTransaction();//一个老师对象Teacher tt = new Teacher("小wang11",11);session.save(tt);//一个课程对象Course course = new Course("数学1111");session.save(course);//老师添加课程，维护中间表tt.getCourses().add(course);//课程添加老师，不会维护中间表//course.getTeachers().add(tt);trans.commit();session.close();}}

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