Hibernate多对多中间表有多个字段字段的注解配置方式（一）

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Hibernate多对多中间表有多个字段字段的注解配置方式（一）

(2011-10-22 13:33:37)

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标签：

hibernate

多对多

中间字段

关系属性

注解配置

分类： Java

一般情况下，多对多的关联关系是需要中间表的；

情况一：如果中间表仅仅是做关联用的，它里面仅有2个外键做联合主键，则使用ManyToMany（不用写中间表的Model，只需要写出两张主表的model即可）

学生表

@Entity
@Table(name = "T_STUDENT")
@SequenceGenerator(name = "SEQ_STUDENT", sequenceName = "SEQ_STUDENT")
public class Student implements Serializable {
private static final long serialVersionUID = 2524659555729848644L;
private Long id;
private String name;
private Date birthday;
private int sex;
private String address;
private Set<Teacher> teacherList;
@Id
@GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "SEQ_STUDENT")
@Column(name = "ID", nullable = false, precision = 22, scale = 0)
public Long getId() {
  return id;
}
public void setId(Long id) {
  this.id = id;
}
@Column(name = "NAME")
public String getName() {
  return name;
}
public void setName(String name) {
  this.name = name;
}
@Temporal(TemporalType.DATE)
@Column(name = "BIRTHDAY")
public Date getBirthday() {
  return birthday;
}
public void setBirthday(Date birthday) {
  this.birthday = birthday;
}
@Column(name = "sex")
public int getSex() {
  return sex;
}
public void setSex(int sex) {
  this.sex = sex;
}
@Column(name = "address")
public String getAddress() {
  return address;
}
public void setAddress(String address) {
  this.address = address;
}
@ManyToMany(cascade = CascadeType.ALL)
@JoinTable(name = "T_TEACHER_STUDENT",
   joinColumns = @JoinColumn(name = "student_id"),
   inverseJoinColumns = @JoinColumn(name = "teacher_id"))
public Set<Teacher> getTeacherList() {
  return teacherList;
}
public void setTeacherList(Set<Teacher> teacherList) {
  this.teacherList = teacherList;
}
}

教师表

@Entity
@Table(name = "T_TEACHER")
@SequenceGenerator(name = "SEQ_TEACHER", sequenceName = "SEQ_TEACHER")
public class Teacher implements Serializable {
private static final long serialVersionUID = 2297316923535111793L;
private Long id;
private String name;
private int sex;
private Set<Student> studentList;
@Id
@GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "SEQ_TEACHER")
@Column(name = "ID", nullable = false, precision = 22, scale = 0)
public Long getId() {
  return id;
}
public void setId(Long id) {
  this.id = id;
}
@Column(name = "name")
public String getName() {
  return name;
}
public void setName(String name) {
  this.name = name;
}
@Column(name = "sex")
public int getSex() {
  return sex;
}
public void setSex(int sex) {
  this.sex = sex;
}
@ManyToMany(mappedBy = "teacherList", cascade = CascadeType.ALL)
public Set<Student> getStudentList() {
  return studentList;
}
public void setStudentList(Set<Student> studentList) {
  this.studentList = studentList;
}
}

hibernate.cfg.xml配置2个class类

测试：

SessionFactory sessionFactory = null;
  Session session = null;
  try {
   sessionFactory = HibernateUtil.getSessionFactory();
   session = sessionFactory.getCurrentSession();
   session.beginTransaction();
   Student s = new Student();
   s.setName("小猪");
   Teacher t = new Teacher();
   t.setName("小李");
   Set<Teacher> t_set = new HashSet<Teacher>();
   t_set.add(t);
   s.setTeacherList(t_set);
   session.save(s);

  } catch (Exception e) {
   if (session != null) {
    session.getTransaction().rollback();
   }
  }

测试通过！！！

很简单吧！注意HibernateUtil.getSessionFactory()的实现如下：

public class HibernateUtil {
private static final SessionFactory sessionFactory;

static {
  try {
   // Create the SessionFactory from hibernate.cfg.xml
   sessionFactory = new AnnotationConfiguration().configure()
     .buildSessionFactory();
  } catch (Throwable ex) {
   // Make sure you log the exception, as it might be swallowed
   System.err.println("Initial SessionFactory creation failed." + ex);
   throw new ExceptionInInitializerError(ex);
  }
}

public static SessionFactory getSessionFactory() {
return sessionFactory;
}
}

如果自己做测试，可以通过SchemaExport导入表结构

SchemaExport export = new SchemaExport(new AnnotationConfiguration()
.configure());
export.create(true, true);

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