hibernate--Student_Course_Score设计

红太狼 2024-02-18 15:00 46阅读 0赞

方式1、中间表Score使用联合主键，采用联合主键的方式稍微繁杂，这里不采用。

方式2、中间表Score不使用联合主键，即添加id作为主键。

![Center][]

Student.java:

package com.bean;
    
    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.JoinColumns;
    import javax.persistence.JoinTable;
    import javax.persistence.ManyToMany;
    import javax.persistence.OneToMany;
    
    @Entity
    public class Student {
    	private int id;
    	private String name;
    	private Set<Score> scores = new HashSet<Score>();
    	private Set<Course> courses = new HashSet<Course>();
    	
    	@OneToMany(mappedBy="student",cascade=CascadeType.ALL,fetch=FetchType.EAGER)
    	public Set<Score> getScores() {
    		return scores;
    	}
    
    	public void setScores(Set<Score> scores) {
    		this.scores = scores;
    	}
    
    	@ManyToMany(cascade=CascadeType.ALL,fetch=FetchType.EAGER)
    	@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;
    	}
    
    }

Score.java:

package com.bean;
    
    import javax.persistence.CascadeType;
    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 grade;
    	private Student student;
    	private Course course;
    
    	@Id
    	@GeneratedValue
    	public int getId() {
    		return id;
    	}
    
    	public void setId(int id) {
    		this.id = id;
    	}
    
    	public int getGrade() {
    		return grade;
    	}
    
    	public void setGrade(int grade) {
    		this.grade = grade;
    	}
    
    	@ManyToOne(cascade=CascadeType.ALL)
    	@JoinColumn(name="student_id")
    	public Student getStudent() {
    		return student;
    	}
    
    	public void setStudent(Student student) {
    		this.student = student;
    	}
    
    	@ManyToOne(cascade=CascadeType.ALL)
    	@JoinColumn(name="course_id")
    	public Course getCourse() {
    		return course;
    	}
    
    	public void setCourse(Course course) {
    		this.course = course;
    	}
    
    }

Course.java:

package com.bean;
    
    import java.util.HashSet;
    import java.util.Set;
    
    import javax.persistence.CascadeType;
    import javax.persistence.Entity;
    import javax.persistence.GeneratedValue;
    import javax.persistence.Id;
    import javax.persistence.ManyToMany;
    
    @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;
    	}
    
    }

[Center]: https://image.dandelioncloud.cn/pgy_files/images/2024/01/29/565d67abec854f4c9c7ec1d12f286a42.png