class UserService
{
    public function register(array $data)
    {
        // 开启事务
        DB::transaction(function () use ($data) {
            $user = User::create($data);

            // 发送邮件
            Mail::to($user->email)->send(new WelcomeEmail($user));

            // 创建默认设置
            UserSetting::create(['user_id' => $user->id]);

            // 记录日志
            activity()->on($user)->log('registered');
        });

        return $user;
    }
}

class AuthController extends Controller
{
    public function register(Request $request, UserService $userService)
    {
        $user = $userService->register($request->all());

        return response()->json($user, 201);
    }
}
</font>
</p>
<p>这样控制器只负责接收请求和返回响应，真正做事的是Service。</p>

<H3>Repository层：解耦数据访问</H3>
<p>Repository的作用是封装对数据库的操作，让Service不需要知道底层是Eloquent还是其他ORM，甚至可以切换数据源。它提供统一的数据接口，比如<code>find()</code>、<code>all()</code>、<code>create()</code>等。</p>
<p>定义一个UserRepository接口：</p>
<font face="Courier New">
<pre class="brush:php;toolbar:false;">
interface UserRepositoryInterface
{
    public function findById($id);
    public function findByEmail($email);
    public function create(array $data);
}

class EloquentUserRepository implements UserRepositoryInterface
{
    public function findById($id)
    {
        return User::find($id);
    }

    public function findByEmail($email)
    {
        return User::where('email', $email)->first();
    }

    public function create(array $data)
    {
        return User::create($data);
    }
}

class UserService
{
    protected $userRepository;

    public function __construct(UserRepositoryInterface $userRepository)
    {
        $this->userRepository = $userRepository;
    }

    public function register(array $data)
    {
        DB::transaction(function () use ($data) {
            $user = $this->userRepository->create($data);

            Mail::to($user->email)->send(new WelcomeEmail($user));

            UserSetting::create(['user_id' => $user->id]);
        });

        return $user;
    }
}

// 在AppServiceProvider的register方法中
$this->app->bind(
    UserRepositoryInterface::class,
    EloquentUserRepository::class
);