laravel excel 报错：Class excel does not exist

in Container.php line 741
at ReflectionClass->__construct('excel') in Container.php line 741
at Container->build('excel', array()) in Container.php line 631
at Container->make('excel', array()) in Application.php line 674
at Application->make('excel') in Container.php line 1167
at Container->offsetGet('excel') in Facade.php line 151
at Facade::resolveFacadeInstance('excel') in Facade.php line 120
at Facade::getFacadeRoot() in Facade.php line 205
at Facade::__callStatic('load', array('new.xlsx', object(Closure))) in ReportController.php line 39
at ReportController->wexport()
at call_user_func_array(array(object(ReportController), 'wexport'), array()) in Controller.php line 256
at Controller->callAction('wexport', array()) in ControllerDispatcher.php line 164
at ControllerDispatcher->call(object(ReportController), object(Route), 'wexport') in ControllerDispatcher.php line 112
at ControllerDispatcher->Illuminate\Routing{closure}(object(Request))
at call_user_func(object(Closure), object(Request)) in Pipeline.php line 139
at Pipeline->Illuminate\Pipeline{closure}(object(Request))
at call_user_func(object(Closure), object(Request)) in Pipeline.php line 102
at Pipeline->then(object(Closure)) in ControllerDispatcher.php line 114
at ControllerDispatcher->callWithinStack(object(ReportController), object(Route), object(Request), 'wexport') in ControllerDispatcher.php line 67
at ControllerDispatcher->dispatch(object(Route), object(Request), 'App\Http\Controllers\ReportController', 'wexport') in Route.php line 203
at Route->runWithCustomDispatcher(object(Request)) in Route.php line 134
at Route->run(object(Request)) in Router.php line 708
at Router->Illuminate\Routing{closure}(object(Request))
at call_user_func(object(Closure), object(Request)) in Pipeline.php line 139
at Pipeline->Illuminate\Pipeline{closure}(object(Request)) in BackendAuth.php line 22
at BackendAuth->handle(object(Request), object(Closure))
at call_user_func_array(array(object(BackendAuth), 'handle'), array(object(Request), object(Closure))) in Pipeline.php line 124
at Pipeline->Illuminate\Pipeline{closure}(object(Request))
at call_user_func(object(Closure), object(Request)) in Pipeline.php line 102
at Pipeline->then(object(Closure)) in Router.php line 710
at Router->runRouteWithinStack(object(Route), object(Request)) in Router.php line 673
at Router->dispatchToRoute(object(Request)) in Router.php line 635
at Router->dispatch(object(Request)) in Kernel.php line 236
at Kernel->Illuminate\Foundation\Http{closure}(object(Request))
at call_user_func(object(Closure), object(Request)) in Pipeline.php line 139
at Pipeline->Illuminate\Pipeline{closure}(object(Request)) in Debugbar.php line 51
at Debugbar->handle(object(Request), object(Closure))
at call_user_func_array(array(object(Debugbar), 'handle'), array(object(Request), object(Closure))) in Pipeline.php line 124
at Pipeline->Illuminate\Pipeline{closure}(object(Request)) in VerifyCsrfToken.php line 50
at VerifyCsrfToken->handle(object(Request), object(Closure))
at call_user_func_array(array(object(VerifyCsrfToken), 'handle'), array(object(Request), object(Closure))) in Pipeline.php line 124
at Pipeline->Illuminate\Pipeline{closure}(object(Request)) in ShareErrorsFromSession.php line 49
at ShareErrorsFromSession->handle(object(Request), object(Closure))
at call_user_func_array(array(object(ShareErrorsFromSession), 'handle'), array(object(Request), object(Closure))) in Pipeline.php line 124
at Pipeline->Illuminate\Pipeline{closure}(object(Request)) in StartSession.php line 62
at StartSession->handle(object(Request), object(Closure))
at call_user_func_array(array(object(StartSession), 'handle'), array(object(Request), object(Closure))) in Pipeline.php line 124
at Pipeline->Illuminate\Pipeline{closure}(object(Request)) in AddQueuedCookiesToResponse.php line 37
at AddQueuedCookiesToResponse->handle(object(Request), object(Closure))
at call_user_func_array(array(object(AddQueuedCookiesToResponse), 'handle'), array(object(Request), object(Closure))) in Pipeline.php line 124
at Pipeline->Illuminate\Pipeline{closure}(object(Request)) in EncryptCookies.php line 59
at EncryptCookies->handle(object(Request), object(Closure))
at call_user_func_array(array(object(EncryptCookies), 'handle'), array(object(Request), object(Closure))) in Pipeline.php line 124
at Pipeline->Illuminate\Pipeline{closure}(object(Request)) in CheckForMaintenanceMode.php line 44
at CheckForMaintenanceMode->handle(object(Request), object(Closure))
at call_user_func_array(array(object(CheckForMaintenanceMode), 'handle'), array(object(Request), object(Closure))) in Pipeline.php line 124
at Pipeline->Illuminate\Pipeline{closure}(object(Request))
at call_user_func(object(Closure), object(Request)) in Pipeline.php line 102
at Pipeline->then(object(Closure)) in Kernel.php line 122
at Kernel->sendRequestThroughRouter(object(Request)) in Kernel.php line 87
at Kernel->handle(object(Request)) in index.php line 53

use Excel；