Java后台通用权限管理系统设计原理
简介
在Java后台开发中,权限管理是一个非常常见的需求。一个通用的权限管理系统可以方便地实现对系统中各个模块和功能的权限控制,提高系统的安全性和稳定性。本文将介绍一个基于Java后台的通用权限管理系统的设计原理,并通过代码示例来说明。
设计原理
数据库设计
权限管理系统的核心是用户、角色和权限的管理。一般而言,我们可以通过数据库来存储这些信息,以下是一个简化的数据库设计示例:
```sql
-- 用户表
CREATE TABLE `user` (
`id` INT(11) NOT NULL AUTO_INCREMENT,
`username` VARCHAR(50) NOT NULL,
`password` VARCHAR(50) NOT NULL,
PRIMARY KEY (`id`)
);
-- 角色表
CREATE TABLE `role` (
`id` INT(11) NOT NULL AUTO_INCREMENT,
`name` VARCHAR(50) NOT NULL,
PRIMARY KEY (`id`)
);
-- 权限表
CREATE TABLE `permission` (
`id` INT(11) NOT NULL AUTO_INCREMENT,
`name` VARCHAR(50) NOT NULL,
PRIMARY KEY (`id`)
);
-- 用户角色关联表
CREATE TABLE `user_role` (
`user_id` INT(11) NOT NULL,
`role_id` INT(11) NOT NULL,
PRIMARY KEY (`user_id`, `role_id`),
FOREIGN KEY (`user_id`) REFERENCES `user`(`id`),
FOREIGN KEY (`role_id`) REFERENCES `role`(`id`)
);
-- 角色权限关联表
CREATE TABLE `role_permission` (
`role_id` INT(11) NOT NULL,
`permission_id` INT(11) NOT NULL,
PRIMARY KEY (`role_id`, `permission_id`),
FOREIGN KEY (`role_id`) REFERENCES `role`(`id`),
FOREIGN KEY (`permission_id`) REFERENCES `permission`(`id`)
);
代码实现
```java
// User.java
public class User {
private int id;
private String username;
private String password;
// getters and setters
}
// Role.java
public class Role {
private int id;
private String name;
// getters and setters
}
// Permission.java
public class Permission {
private int id;
private String name;
// getters and setters
}
// UserRepository.java
public interface UserRepository {
User findByUsername(String username);
}
// RoleRepository.java
public interface RoleRepository {
Role findById(int id);
}
// PermissionRepository.java
public interface PermissionRepository {
Permission findById(int id);
}
// UserRepositoryImpl.java
public class UserRepositoryImpl implements UserRepository {
@Override
public User findByUsername(String username) {
// 数据库查询实现
}
}
// RoleRepositoryImpl.java
public class RoleRepositoryImpl implements RoleRepository {
@Override
public Role findById(int id) {
// 数据库查询实现
}
}
// PermissionRepositoryImpl.java
public class PermissionRepositoryImpl implements PermissionRepository {
@Override
public Permission findById(int id) {
// 数据库查询实现
}
}
// UserService.java
public class UserService {
private UserRepository userRepository;
private RoleRepository roleRepository;
public void setUserRepository(UserRepository userRepository) {
this.userRepository = userRepository;
}
public void setRoleRepository(RoleRepository roleRepository) {
this.roleRepository = roleRepository;
}
public boolean hasPermission(String username, String permissionName) {
User user = userRepository.findByUsername(username);
if (user == null) {
return false;
}
Role role = roleRepository.findById(user.getRoleId());
if (role == null) {
return false;
}
Permission permission = role.getPermissions().stream()
.filter(p -> p.getName().equals(permissionName))
.findAny()
.orElse(null);
return permission != null;
}
}
// PermissionService.java
public class PermissionService {
private PermissionRepository permissionRepository;
public void setPermissionRepository(PermissionRepository permissionRepository) {
this.permissionRepository = permissionRepository;
}
public Permission findById(int id) {
return permissionRepository.findById(id);
}
}
序列图
下面是一个描述用户登录并检查权限的序列图,使用mermaid语法标识:
```mermaid
sequenceDiagram
participant Client
participant UserService
participant UserRepository
participant RoleRepository
Client->>UserService: hasPermission(username, permissionName)
UserService->>UserRepository: findByUsername(username)
UserRepository->>UserService: user
UserService->>RoleRepository: findById(user.roleId)
RoleRepository->>UserService: role
UserService->>Role: getPermissions()
loop for each permission
UserService->>Permission: getName()
Permission->>UserService: permissionName
alt permissionName is equal