Hibernate学习笔记_关系映射_学生_课程_分数

1         学生课程、分数的设计(重要)

@Entity
public class Student {
    private int id;
    private String name;
    private Set<Course> courses = new HashSet<Course>();
    
    @ManyToMany
    @JoinTable(name="score",
        joinColumns=@JoinColumn(name="student_id"),
        inverseJoinColumns=@JoinColumn(name="course_id")
        )
    public Set<Course> getCourses() {
        return courses;
    }
    public void setCourses(Set<Course> courses) {
        this.courses = courses;
    }
    @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 Course {
    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
@Table(name="score")
public class Score {
    private int id;
    private int score;
    private Student student;
    private Course course;
    @Id
    @GeneratedValue
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public int getScore() {
        return score;
    }
    public void setScore(int score) {
        this.score = score;
    }
    @ManyToOne
    @JoinColumn(name="student_id")
    public Student getStudent() {
        return student;
    }
    public void setStudent(Student student) {
        this.student = student;
    }
    
    @ManyToOne
    @JoinColumn(name="course_id")
    public Course getCourse() {
        return course;
    }
    public void setCourse(Course course) {
        this.course = course;
    }
    
}

@Test
    public void testSave() {
        Student s = new Student();
        s.setName("zhangsan");
        Course c = new Course();
        c.setName("java");
        Score score = new Score();
        score.setCourse(c);
        score.setStudent(s);
        
        Session session = sessionFactory.openSession();
        session.beginTransaction();
        session.save(s);
        session.save(c);
        session.save(score);
    
        session.getTransaction().commit();
        session.close();
    }
    @Test
    public void testLoad() {
        testSave();
        Session session = sessionFactory.openSession();
        session.beginTransaction();
        
        Student s = (Student)session.load(Student.class, 1);
        for(Course c : s.getCourses()) {
            System.out.println(c.getName());
        }
        
        session.getTransaction().commit();
        session.close();
        
    }