学生和课程是多对多，一个学生的一个课程只能对应一个成绩。

所以学生和课程多对多，其中间表多了一个成绩字段。

可以这样设计：

学生和课程通过中间表--成绩，多对多映射。

 

 

手动建中间表语句：

create table score(id int primary key auto_increment,student_id int refrences student(id),course_id int references course(id),score int);

 

 

package com.bjsxt.hibernate;

import javax.persistence.Entity;

import javax.persistence.GeneratedValue;

import javax.persistence.Id;

@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;

    }

   

}

 

 

package com.bjsxt.hibernate;

import javax.persistence.Entity;

import javax.persistence.GeneratedValue;

import javax.persistence.Id;

import javax.persistence.JoinColumn;

import javax.persistence.ManyToOne;

import javax.persistence.Table;

@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;

    }

   

}

 

 

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.JoinTable;

import javax.persistence.ManyToMany;

@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", referencedColumnName="id"),

        inverseJoinColumns=@JoinColumn(name="course_id", referencedColumnName="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;

    }

   

}

 

 

测试类

package com.bjsxt.hibernate;

import java.util.Map;

import org.hibernate.Session;

import org.hibernate.SessionFactory;

import org.hibernate.cfg.AnnotationConfiguration;

import org.hibernate.tool.hbm2ddl.SchemaExport;

import org.junit.AfterClass;

import org.junit.BeforeClass;

import org.junit.Test;

public class HibernateTreeTest {

    private static SessionFactory sessionFactory;

   

    @BeforeClass

    public static void beforeClass() {

        //new SchemaExport(new AnnotationConfiguration().configure()).create(false, true);

        sessionFactory = new AnnotationConfiguration().configure().buildSessionFactory();

    }

    @AfterClass

    public static void afterClass() {

        sessionFactory.close();

    }

   

    @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();

       

    }

   

   

    @Test

    public void testSchemaExport() {

        new SchemaExport(new AnnotationConfiguration().configure()).create(false, true);

    }

   

   

    public static void main(String[] args) {

        beforeClass();

    }

}