Question

我是hibernate-spring tirple的新手..

我只是尝试编写简单的注册簿..我有以下代码：

Student.java

@Entity(name = "STUDENTS")
@NamedQueries({
    @NamedQuery(name = "getAllStudent", query = "SELECT k FROM STUDENTS k ORDER BY k.id DESC"),
    @NamedQuery(name = "findByName", query = "SELECT k FROM STUDENTS k WHERE k.name LIKE :name")
})
public class Student {

    @Column(name = "STUDENTNO", nullable = false)
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;
    @Column(name = "NAME", nullable = false)
    private String name;
    @Column(name = "SURNAME")
    private String surname;
    @Column(name = "AGE")
    private String age;
    // GET ve SET metods

StduentDAO.java

@Repository
@Transactional(readOnly = true)
public class StudentDAO implements IStudentDAO {

    @PersistenceContext
    EntityManager em;

    @Override
        public void deleteStudent(Student student) {
        Student temp = em.getReference(Student.class, student.getId());
        em.remove(temp);
        System.out.println("### getting out from studentDAO deleteStudent method ###")

StudentController.java

@Component
@Scope(value = "request")
public class StudentController {

@Autowired
IStudentDAO studentDAO;
List<Student> allStudentList = new ArrayList();
Student student = new Student();

@PostConstruct
 private void loadStudents() {
 allStudentList = studentDAO.allStudent();

 public void deleteStudent() {
 studentDAO.deleteStudent(student);
 System.out.println("### getting out from StudentController deleteStudent method ### ");
 }

当我运行deleteStudent()代码时，我得到了：

“###退出studentDAO deleteStudent方法###”

“###从StudentController中删除deleteStudent方法###”

我在输出上看到这些但没有从数据库中删除..我搜索了一下，我发现这“每个权利经理的方法都打开了自己的会话。”这就是为什么它说我应该像上面那样编写我的StudentDAO的deleteStudent方法..

我想我错过了关于交易的一些事情，但我还没有认识到..

我该怎么办？

谢谢..

Answer 1

@Transactional注释在您的DBMS上创建一个事务。

如果使用（readOnly = true），则会阻止对DB的操作（如INSERT / UPDATE / DELETE）。

删除readOnly = true，这样你的删除方法就可以了。

如何从数据库中删除实体

1 个答案: