JPA关系映射之one-to-many和many-to-one

Posted 2020-08-01 SaraMorning

one-to-many（一对多）和many-to-one（多对一）双向关联

假设教师与学生是一对多关系，反过来学生与教师就是多对一关系。

1、Teacher.java

 1 public class Teacher {  
 2     private long id;  
 3     private String teaName;  
 4     private Set<Student> students = new HashSet<Student>();  
 5     public long getId() {  
 6         return id;  
 7     }  
 8     public void setId(long id) {  
 9         this.id = id;  
10     }  
11     public String getTeaName() {  
12         return teaName;  
13     }  
14     public void setTeaName(String teaName) {  
15         this.teaName = teaName;  
16     }  
17       
18     public Set getStudents() {  
19         return students;  
20     }  
21     public void setStudents(Set students) {  
22         this.students = students;  
23     }  
24     public String toString() {  
25         return "Teacher:[teacherId=" + this.id + "/tteacherName="  
26                 + this.teaName + "]";  
27     }  
28 } 

Student.java

 1 public class Student {
 2     private long id;
 3     private String stuName;
 4     private Teacher teacher;
 5 
 6     public long getId() {
 7         return id;
 8     }
 9 
10     public void setId(long id) {
11         this.id = id;
12     }
13 
14     public String getStuName() {
15         return stuName;
16     }
17 
18     public void setStuName(String stuName) {
19         this.stuName = stuName;
20     }
21 
22     public Teacher getTeacher() {
23         return teacher;
24     }
25 
26     public void setTeacher(Teacher teacher) {
27         this.teacher = teacher;
28     }
29 
30     public String toString() {
31         return "student:[studentId=" + this.id + "/tstudentName="
32                 + this.stuName + "]";
33     }
34 }

 

 

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