【hibernate框架】练习-学生、课程、分数的设计(重要)

学生、课程、分数的设计(重要)

表设计：
方法1：
设置联合主键@EmbeddedId
实现Serializable接口

student:id<int> name<String>
course:id<int> name<String>
score:studentid<int> courseid<int> score<int>//联合主键联合id
//有点麻烦不写了，直接看方法2吧

方法2：
student:id<int> name<String>
course:id<int> name<String>
score:id<int> studentid<int> courseid<int> score<int>//这一方设ManyToOne

实现代码：
Student.java:

package cn.edu.hpu.testSchool;

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;
import javax.persistence.Table;


@Entity
@Table(name="s_student")
public class Student {
	private int id;
	private String name;
	private Set<Course> courses=new HashSet<Course>();
	
	@ManyToMany
	@JoinTable(name="s_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;
	}
	
}

Score.java:

package cn.edu.hpu.testSchool;

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="s_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="studnet_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;
	}
	
}

Course.java:

package cn.edu.hpu.testSchool;


import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Table;


@Entity
@Table(name="s_course")
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;
	}
	
}

在hibernate.cfg.xml配置：

<mapping class="cn.edu.hpu.testSchool.Student"/> 
<mapping class="cn.edu.hpu.testSchool.Score"/>
<mapping class="cn.edu.hpu.testSchool.Course"/>

建表语句：

create table s_course (

         id integer not null auto_increment,

         name varchar(255),

         primary key (id)

     )



     create table s_score (

         id integer not null,

         score integer not null,

         course_id integer,

         student_id integer not null auto_increment,

         primary key (student_id, course_id)

     )



     create table s_student (

         id integer not null auto_increment,

         name varchar(255),

         primary key (id)

     )



     alter table s_score 

         add index FK6C0C3FC68B2C002E (student_id), 

         add constraint FK6C0C3FC68B2C002E 

         foreign key (student_id) 

         references s_student (id)



     alter table s_score 

         add index FK6C0C3FC6EFAFE106 (course_id), 

         add constraint FK6C0C3FC6EFAFE106 

         foreign key (course_id) 

         references s_course (id)

结果：

student:id<int> name<String>

 course:id<int> name<String>

 score:id<int> studentid<int> courseid<int> score<int>

测试添加：

@Test
public void testSchoolAdd(){
	cn.edu.hpu.testSchool.Student s=new cn.edu.hpu.testSchool.Student();
	s.setName("zhangsan");
	Course c=new Course();
	c.setName("java");
	Score score=new Score();
	score.setCourse(c);
	score.setStudent(s);
	score.setScore(80);
	
	
	sessionFactory=new AnnotationConfiguration().configure().buildSessionFactory();
	Session session=sessionFactory.openSession();
	session.beginTransaction();
	session.save(s);
	session.save(c);
	session.save(score);
	session.getTransaction().commit();
	session.close();
}

结果：

Hibernate: 

     insert 

     into

         s_student

         (name) 

     values

         (?)

 Hibernate: 

     insert 

     into

         s_course

         (name) 

     values

         (?)

 Hibernate: 

     insert 

     into

         s_score

         (course_id, score, student_id) 

     values

         (?, ?, ?)

测试取数据：

@Test
public void testSchoolLoad(){


	sessionFactory=new AnnotationConfiguration().configure().buildSessionFactory();
	Session session=sessionFactory.openSession();
	session.beginTransaction();
	cn.edu.hpu.testSchool.Student s=(cn.edu.hpu.testSchool.Student)session.load(cn.edu.hpu.testSchool.Student.class, 2);
	for(Course c:s.getCourses()){
		System.out.println(c.getName());
	}
	session.getTransaction().commit();
	session.close();
}

结果：

Hibernate: 

     select

         student0_.id as id0_0_,

         student0_.name as name0_0_ 

     from

         s_student student0_ 

     where

         student0_.id=?

 Hibernate: 

     select

         courses0_.student_id as student4_0_1_,

         courses0_.course_id as course3_1_,

         course1_.id as id2_0_,

         course1_.name as name2_0_ 

     from

         s_score courses0_ 

     inner join

         s_course course1_ 

             on courses0_.course_id=course1_.id 

     where

         courses0_.student_id=?

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