用户，角色，权限的Java 代码

以下是一个基于Spring Security框架的用户、角色、权限Java代码示例，供您参考：

1. 用户实体类

@Entity
@Table(name = "user")
public class User implements Serializable {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String name;
    private String password;
    private boolean enabled;
    @ManyToMany(fetch = FetchType.EAGER)
    @JoinTable(name = "user_role", joinColumns = @JoinColumn(name = "user_id"), inverseJoinColumns = @JoinColumn(name = "role_id"))
    private Set<Role> roles = new HashSet<>();
    // 省略getter和setter方法
}

2. 角色实体类

@Entity
@Table(name = "role")
public class Role implements Serializable {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String name;
    @ManyToMany(mappedBy = "roles")
    private Set<User> users = new HashSet<>();
    @ManyToMany(fetch = FetchType.EAGER)
    @JoinTable(name = "role_permission", joinColumns = @JoinColumn(name = "role_id"), inverseJoinColumns = @JoinColumn(name = "permission_id"))
    private Set<Permission> permissions = new HashSet<>();
    // 省略getter和setter方法
}

3. 权限实体类

@Entity
@Table(name = "permission")
public class Permission implements Serializable {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String name;
    @ManyToMany(mappedBy = "permissions")
    private Set<Role> roles = new HashSet<>();
    // 省略getter和setter方法
}

4. 用户、角色、权限数据访问层接口

public interface UserRepository extends JpaRepository<User, Long> {
    User findByName(String name);
}
public interface RoleRepository extends JpaRepository<Role, Long> {
    Role findByName(String name);
}
public interface PermissionRepository extends JpaRepository<Permission, Long> {
    Permission findByName(String name);
}

5. 用户、角色、权限服务层接口和实现类

public interface UserService {
    User save(User user);
    User findByName(String name);
}
@Service
public class UserServiceImpl implements UserService {
    @Autowired
    private UserRepository userRepository;
    @Override
    public User save(User user) {
        return userRepository.save(user);
    }
    @Override
    public User findByName(String name) {
        return userRepository.findByName(name);
    }
}
public interface RoleService {
    Role save(Role role);
    Role findByName(String name);
}
@Service
public class RoleServiceImpl implements RoleService {
    @Autowired
    private RoleRepository roleRepository;
    @Override
    public Role save(Role role) {
        return roleRepository.save(role);
    }
    @Override
    public Role findByName(String name) {
        return roleRepository.findByName(name);
    }
}
public interface PermissionService {
    Permission save(Permission permission);
    Permission findByName(String name);
}
@Service
public class PermissionServiceImpl implements PermissionService {
    @Autowired
    private PermissionRepository permissionRepository;
    @Override
    public Permission save(Permission permission) {
        return permissionRepository.save(permission);
    }
    @Override
    public Permission findByName(String name) {
        return permissionRepository.findByName(name);
    }
}

6. 用户、角色、权限控制器

@Controller
public class UserController {
    @Autowired
    private UserService userService;
    @Autowired
    private RoleService roleService;
    @Autowired
    private PermissionService permissionService;
    @GetMapping("/register")
    public String register() {
        return "register";
    }
    @PostMapping("/register")
    public String register(User user) {
        user.setEnabled(true);
        userService.save(user);
        Role role = roleService.findByName("ROLE_USER");
        role.getUsers().add(user);
        roleService.save(role);
        return "redirect:/login";
    }
}

这只是基于Spring Security框架的一个简单示例，具体实现方式可能因不同的需求而有所差异。您可以根据自己的具体需求进行调整和扩展。