如何使用ehcache使用对象不拥有的键来缓存对象？

Question

I am fairly new to ehcache and as far as I know on method level the cacheing is working on the id of object to be cached. However I have a different situation.

I have a User class and a role class, the relation between them is many-to-many and stored in another table by ids.

public class User{
    @Id
    @Column(name="ID")
    @GeneratedValue(generator="idGenerator",strategy = GenerationType.SEQUENCE)
    private Long id;

    ...

    @ManyToMany(targetEntity = Role.class, fetch = FetchType.EAGER)
    @JoinTable(name = "ROLE", joinColumns = { @JoinColumn(name = "USER_ID") }, inverseJoinColumns = { @JoinColumn(name = "ROLE_ID") })
    protected Set<Role> roles;

    ...

}


public class Role{
    @Id
    @Column(name="ID")
    @GeneratedValue(generator="idGenerator",strategy = GenerationType.SEQUENCE)
    private Long id;

    ...

    @ManyToMany(targetEntity = User.class)
    @JoinTable(name = "USER", joinColumns = { @JoinColumn(name = "ROLE_ID") }, inverseJoinColumns = { @JoinColumn(name = "USER_ID") })
    protected Set<Role> roles;

    ...

}

Just to mention, there no such a UserRole domain class.

And the service method is somethig like;

public RoleService{

    @Cacheable
    public Set<Role> getUserRoles(Long userId)
    {
        ...
    }
}

The thing is that on the service level I want the roles to be cached per userId basis. How can I cache roles using id of the user?

Answer 1

If you use ehcache for method caching with spring it should work out of the box.

<ehcache:annotation-driven cache-manager="ehCacheManager" />

@Cacheable(name="getUserRoles", key="userId")

See Ehcache Spring documentation .