class MidParams //中间件
{
 public function handle($request, Closure $next)
 {
  $mid_params = ['mid_params'=>'this is mid_params'];
  $request->attributes->add($mid_params);//添加参数

  return $next($request);//进行下一步(即传递给控制器)
 }
}

class MidController extends Controller { //控制器
 public function testMidFunc(Request $request) {
  $input_params = $request->input();//获取参数
  $mid_params = $request->get('mid_params');//中间件产生的参数
  return ['my_params'=>$input_params,
  'mid_params'=>$mid_params];
  //注意：$request->attributes->add这种方法 input()取不到值  只能用get('xxx')取到值
 }
}

class MidParams //中间件
{
 public function handle($request, Closure $next)
 {
  $mid_params = ['mid_params'=>'this is mid_params'];
  $request->merge($mid_params);//合并参数
  return $next($request);
 }
}

class MidController extends Controller { //控制器
 public function testMidFunc(Request $request) {
  $all_params = $request->input();//获取参数
  return ['all_params'=>$all_params];
 }
}