Java 两种方式的角色管理

Question

我正在设计一些具有用户和团队的 Java 应用程序：

public abstract class AbstractUser()

public class BasicUser extends AbstractUser()

public class AnotherUser extends AbstractUser()

现在我有包含用户的团队：

public abstract class AbstractTeam() {

  protected List<AbstractUser> members;

}

public class PublicTeam extends AbstractTeam()

现在我需要管理团队，所以每个用户都应该有一个团队状态，例如成员、版主、管理员、所有者等。

于是想到做一些接口：

public Interface TeamRole

public Interface Member extends TeamRole

public Interface Moderator extends TeamRole

并让 AbsractUser 类实现 TeamRole：

public abstract class AbstractUser implements TeamRole

现在我想做的是：让一个控制器来处理删除用户创建的条目：

public boolean deleteEntry(User u, Entry e, requestingUser r) {

}

如何获得干净的表示，以便我可以执行以下操作：

u.getEntries().removeIf(entry -> entry.equals(e));

在不“尝试”if 语句中的所有角色的情况下以一种干净的方式？

更新：这听起来可能不太“好”，但这只是为了描述执行操作时检查权限的问题

Answer 1

首先，充满鳗鱼的气垫船正确地说AbstractUser应该组合TeamRole而不是继承它（因为它是“有”关系而不是“是”关系）。现在到手头的问题。我不确定我是否完全理解您的要求，但是我假设您是在询问如何在AbstractUser不使用iforswitch语句进行检查的情况下检查是否具有执行操作的权限（或权限）。如果是这样，那么这里有一种方法（在我能想到的几种方法中）。创建一个Enum权限级别，每个权限级别都有一个与权限级别直接相关的序数。下面是一个基本的例子：class enum PermissionLevel {&nbsp; &nbsp; MEMBER(0),&nbsp; &nbsp; MODERATOR(1)&nbsp; &nbsp; private final int level;&nbsp; &nbsp; PermissionLevel(int level) {&nbsp; &nbsp; &nbsp; &nbsp; this.level = level;&nbsp;&nbsp; &nbsp; }&nbsp; &nbsp; public int getLevel() {&nbsp; &nbsp; &nbsp; &nbsp; return level;&nbsp; &nbsp; }}现在给TeamRole接口一个返回与该角色关联的权限级别的方法public Interface TeamRole {&nbsp; &nbsp; PermissionLevel getPermissionLevel();&nbsp; &nbsp; ...}现在，检查时，如果一个成员有权所有你需要做的是对的权限级别的整数比较TeamRole的AbstractUser了。if (user.getTeamRole().getPermissionLevel().getLevel() > PermissionLevel.MEMBER.getLevel()) {&nbsp; &nbsp; // User has permission to do this action}

Answer 2

我知道已经有了答案，但我想我可以分享一个不同的想法，我们将使用继承来表达角色层次结构和方法签名来约束操作。这是一般的设计思路：用法：public class TeamApplicationService {&nbsp; &nbsp; public void doSomethingSpecial(final String teamId) {&nbsp; &nbsp; &nbsp; &nbsp; final Team team = teamRepository.teamOfId(teamId);&nbsp; &nbsp; &nbsp; &nbsp; final TeamModerator moderator = team.findModerator(currentUserId);&nbsp; &nbsp; &nbsp; &nbsp; team.doSomethingSpecial(moderator);&nbsp; &nbsp; }}public class Team {&nbsp; &nbsp; final Map<String, TeamMember> teamMembers;&nbsp; &nbsp; public Team() {&nbsp; &nbsp; &nbsp; &nbsp; teamMembers = new HashMap<String, TeamMember>();&nbsp; &nbsp; }&nbsp; &nbsp; public void addMember(final TeamMember member) {&nbsp; &nbsp; &nbsp; &nbsp; teamMembers.put(member.userId(), member);&nbsp; &nbsp; }&nbsp; &nbsp; private <T> T findMemberOfRole(final Class<T> clazz, final String userId) {&nbsp; &nbsp; &nbsp; &nbsp; if (!teamMembers.containsKey(userId)) throw couldNotFindMember();&nbsp; &nbsp; &nbsp; &nbsp; try {&nbsp; &nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; return (T)clazz.cast(teamMembers.get(userId));&nbsp; &nbsp; &nbsp; &nbsp; } catch (java.lang.ClassCastException e) {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; throw couldNotFindMember();&nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; }&nbsp; &nbsp; private RuntimeException couldNotFindMember() {&nbsp; &nbsp; &nbsp; &nbsp; return new RuntimeException("Could not find member");&nbsp; &nbsp; }&nbsp; &nbsp; public TeamModerator findModerator(final String userId) {&nbsp; &nbsp; &nbsp; &nbsp; return this.<TeamModerator>findMemberOfRole(TeamModerator.class, userId);&nbsp; &nbsp; }&nbsp; &nbsp; public TeamMember findMember(final String userId) {&nbsp; &nbsp; &nbsp; &nbsp; return this.<TeamMember>findMemberOfRole(TeamMember.class, userId);&nbsp; &nbsp; }&nbsp; &nbsp; public void doSomethingSpecial(TeamModerator moderator) {&nbsp; &nbsp; &nbsp; &nbsp; //Moderator only&nbsp; &nbsp; }&nbsp; &nbsp; public void doSomethingGeneral(TeamMember member) {&nbsp; &nbsp; &nbsp; &nbsp; //Any member&nbsp; &nbsp; }}编辑：我不完全确定要求，但这里有一个基于评论的更复杂的例子。

Answer 3

TeamRole 成为删除策略（也许重命名？）。可以使用更多的重构，但我认为一般的想法会奏效。如果我们有更多的角色，我们可以添加更多的类并实现它们如何处理删除。public class Entry{}public class User extends AbstractUser{}public abstract class AbstractUser {&nbsp; &nbsp; TeamRole role;&nbsp; &nbsp; List<Entry> entries;&nbsp; &nbsp; //self deletes are always ok&nbsp; &nbsp; public void deleteEntry(Entry e){&nbsp; &nbsp; &nbsp; &nbsp; this.getEntries().removeIf(entry -> entry.equals(e));&nbsp; &nbsp; }&nbsp; &nbsp; //delete depending on requested user role&nbsp; &nbsp; public void deleteEntry(User requestBy, Entry e){&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; role.delete(this, e, requestBy);//mod or other poeple with ability to delete.&nbsp; &nbsp; }&nbsp; &nbsp; public List<Entry> getEntries() {&nbsp; &nbsp; &nbsp; &nbsp; return entries;&nbsp; &nbsp; }};public class BasicUser extends AbstractUser {};public class AnotherUser extends AbstractUser {};public abstract class AbstractTeam {&nbsp; &nbsp; protected List<AbstractUser> members;}public class PublicTeam extends AbstractTeam {};public interface TeamRole{&nbsp; &nbsp; public void delete(AbstractUser user, Entry entry, User requester);}public class Member implements TeamRole{&nbsp; &nbsp; @Override&nbsp; &nbsp; public void delete(AbstractUser user, Entry entry, User requester) {&nbsp; &nbsp; &nbsp; &nbsp; if(user==requester) {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; user.deleteEntry(entry);&nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; }}public class Moderator implements TeamRole{&nbsp; &nbsp; @Override&nbsp; &nbsp; public void delete(AbstractUser user, Entry entry, User requester) {&nbsp; &nbsp; &nbsp; &nbsp; user.deleteEntry(entry);&nbsp; &nbsp; }}