Hibernate 再接触 树状结构设计以及学生课程成绩表的设计

1 树状结构的设计

package com.bjsxt.hibernate;

import java.util.HashSet;
import java.util.Set;

import javax.persistence.CascadeType;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.OneToMany;

@Entity
public class Org {
    private int id;
    private String name;
    private Set<Org> children = new HashSet<Org>();
    private Org parent;
    @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;
    }
    @OneToMany(cascade=CascadeType.ALL, mappedBy="parent")
    public Set<Org> getChildren() {
        return children;
    }
    public void setChildren(Set<Org> children) {
        this.children = children;
    }
    
    @ManyToOne
    @JoinColumn(name="parent_id")
    public Org getParent() {
        return parent;
    }
    public void setParent(Org parent) {
        this.parent = parent;
    }
}

    @Test
    public void testSave() {
        Org o = new Org();
        o.setName("总公司");
        Org o1 = new Org();
        o1.setName("分公司1");
        Org o2 = new Org();
        o2.setName("分公司2");
        Org o11 = new Org();
        o11.setName("分公司1下部门1");
        Org o12 = new Org();
        o12.setName("分公司1下部门2");
        
        o.getChildren().add(o1);
        o.getChildren().add(o2);
        o1.getChildren().add(o11);
        o1.getChildren().add(o12);
        o11.setParent(o1);
        o12.setParent(o1);
        o1.setParent(o);
        o2.setParent(o);
                
        
        Session session = sessionFactory.openSession();
        session.beginTransaction();
        session.save(o);
    
        session.getTransaction().commit();
        session.close();
    }
    @Test
    public void testLoad() {
        testSave();
        Session session = sessionFactory.openSession();
        session.beginTransaction();
        Org o = (Org)session.load(Org.class, 1);
        print(o, 0);
        session.getTransaction().commit();
        session.close();
        
    }
    
    private void print(Org o, int level) {    //输出
        String preStr = "";
        for(int i=0; i<level; i++) {         //缩进
            preStr += "----";
        }
        System.out.println(preStr + o.getName());
        for(Org child : o.getChildren()) {
            print(child, level+1);
        }
    }

Course

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;
    }
    
}

score

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;
    }
    
}

Student

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;
    }
    
}

@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();
        
    }