JPA关系映射之one-to-many和many-to-one

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 }

sdfd