1、怎样输出视图
        namespace App\Http\Controllers;
        class MemberController extends Controller {
            public function index() {
                return view('member');
            }
        }
        Route::get('member/index', 'MemberController@index');
    2、一个控制器对应一个view文件夹
        app/Http/Controllers/MemberController.php
            namespace App\Http\Controllers;
            class MemberController extends Controller {
                public function index() {
                    return view('member/member');
                }
            }
        app/Http/routes.php    
            Route::get('member/index', 'MemberController@index');
        resources/views/member/member.blade.php
            my name is member  
    3、将控制器的数据输出到视图文件上     
        Route::get('member/index', 'MemberController@index');
        namespace App\Http\Controllers;
        class MemberController extends Controller {
            public function index() {
                return view('member/member', [
                    'name' => 'gengen',
                    'age'  => 18
                ]);
            }
        }    
        my name is member
        {{$name}}
        {{$age}}
    4、循环数据
        @foreach($all_knowledge as $key => $value)
            {{$value->title}}
        @endforeach
    5、页面跳转
        return redirect('/uploadknowledge');