mvc中webapi里使用autofac，报错没有默认构造函数

在使用webapi和autofac的时候，报错没有默认构造函数，后来安装了Autofac.WebApi2，还是报错，后来添加了一句话好了

// 注册组件
var builder = new ContainerBuilder();
var services = Assembly.Load("LS.Cores");

// 注册单个实例
//builder.RegisterInstance(new MovieRepository()).As<IMovieRepository>();
//builder.RegisterType <HomeController>();

//注册controlls实例
builder.RegisterApiControllers(Assembly.GetExecutingAssembly());
builder.RegisterControllers(Assembly.GetExecutingAssembly());

// 扫描assembly中的组件
builder.RegisterAssemblyTypes(services)
.Where(t => t.Name.EndsWith("Service"))
.AsImplementedInterfaces();

IContainer container = builder.Build();
DependencyResolver.SetResolver(new AutofacDependencyResolver(container));

GlobalConfiguration.Configuration.DependencyResolver = new AutofacWebApiDependencyResolver(container);

红色字体为后来添加的