Epoll：它会默默地删除fds吗？(Epoll: does it silently remove fds?)

 没有问题不在数据库的连接中，hibernate确定其策略来检查基于id上的注释位置的配置注释（在属性本身或方法上） 
 
 在您的User类中，您告诉hibernate期望属性级别上的注释 
 
public class User {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
@Column(name="user_id")
private int id;
 
 因此，对于hibernate，您没有其他类似角色的映射，因为它不会检查映射的方法，因此您需要做的是从方法中获取注释并将其放在属性中 
 
@ManyToMany
@JoinTable(name="user_role", joinColumns = @JoinColumn(name="user_id"), inverseJoinColumns = @JoinColumn(name="role_id"))
private Set<Role> roles;
 
 您需要在所有注释中执行此操作 

No, the problem is not in the connection of the database. Hibernate determines its policy to check the configuration annotations based on the annotation place on the id (on the attribute itself or on a method).
 
In your User class, you are telling hibernate to expect the annotations on the attribute level.
 
public class User {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
@Column(name="user_id")
private int id;
 
So for hibernate you do not have a mapping for other attribute like roles because it will not check the methods for the mapping, so what you need to do is to take the annotation from the method and put it in the attribute.
 
@ManyToMany
@JoinTable(name="user_role", joinColumns = @JoinColumn(name="user_id"), inverseJoinColumns = @JoinColumn(name="role_id"))
private Set<Role> roles;
 
You need to do this in all your annotations.