使用Spring Boot框架构建基于Spring JPA的DAO的正确方法

Question

另外，假设数据库已经创建和填充。

这描绘了一个学生有多门课程...

我的学生实体：

@Entity
public class Student {

    @OneToMany(mappedBy="student")
    private List<Courses> courses;

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "Student_Id")
    private long studentId;

    @Column(name = "Student_Name")
    private String studentName;

    protected Student() { }

    // Getters & Setters
}

@Entity
public class Course {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "Course_Id")
    private long courseId;

    @Id
    @Column(name = "Student_Id")
    private long studentId;

    @ManyToOne
    @PrimaryKeyJoinColumn(name="Student_Id", referencedColumnName="Student_Id")
    private Student student;

    @Column(name = "Course_Name")
    private String courseName;

    // Getters & Setters

}

public interface CourseDao {
    List<Course> findCoursesByStudentName(String studentName);
}

@Repository
public class CourseDaoImpl implements CourseDao {

    @PersistenceContext
    EntityManager em;

    public List<Course> findCoursesByStudentName(String studentName) {
        String sql = "select c.courseName" +
                     "from Course c, Student s " +
                     "where c.course_id = s.student_id " +
                     "and s.studentName = :studentName ";

        Query query = em.createQuery(sql);
        query.setParameter("studentName", studentName);
        return query.getResultList();
    }
}   

 public class Application {

    @Autowired
    CustomerDao dao;

    public static void main (String args []) {
        List<Course> courses = dao.findCoursesByStudentName("John");
    }   
 }

Spring Boot指南没有描述联接或DAOS-我只需要学习如何正确地创建finder方法，这些方法模拟select语句，返回列表或数据结构。

感谢你花时间阅读这篇文章...

Answer 1

如果我正确理解你的问题，你有两个问题：

1. 如何创建DAO和DAOImpl？
2. 将事务注释放在哪里？

关于第一个问题，我想指出，这是关于spring-data-jpa使用Hibernate作为JPA提供者的问题，而不是spring-boot。

@Repository
public interface StudentRepository extends CrudRepository<Student, Long> {

    List<Student> findByStudentName(String studentName);

}

@Autowired
StudentRepository studentRepo; 

@Repository
public interface @CourseRepository extends CrudRepository<Course, Long> {

    @Query("select c.courseName from Course c, Student s where c.course_id = s.student_id and s.studentName = :studentName")
    public List<Course> findCoursesByStudentName(String studentName);

}