最近想學習一下做WebApi，用Autofac實現自動注入，整了半天都不好使，原來這個WebApi的註冊方式跟Mvc是有區別的，話不多說直接上代碼
Global.asax文件中做如下修改：
protected void Application_Start()
{
#region 自動注入
//創建autofac管理註冊類的容器實例
var builder = new ContainerBuilder();
HttpConfiguration config = GlobalConfiguration.Configuration;
Assembly[] assemblies = Directory.GetFiles(AppDomain.CurrentDomain.RelativeSearchPath, "*.dll").Select(Assembly.LoadFrom).ToArray();
//註冊所有實現了 IDependency 接口的類型
Type baseType = typeof(IDependency);
builder.RegisterAssemblyTypes(assemblies)
.Where(type => baseType.IsAssignableFrom(type) && !type.IsAbstract)
.AsSelf().AsImplementedInterfaces()
.PropertiesAutowired().InstancePerLifetimeScope();
//註冊MVC類型
// builder.RegisterControllers(assemblies).PropertiesAutowired();
//註冊Api類型
builder.RegisterApiControllers(assemblies).PropertiesAutowired();
//builder.RegisterFilterProvider();
builder.RegisterWebApiFilterProvider(config);
var container = builder.Build();
//註冊api容器需要使用HttpConfiguration對象
config.DependencyResolver = new AutofacWebApiDependencyResolver(container);
//註冊解析
DependencyResolver.SetResolver(new AutofacDependencyResolver(container));
#endregion
AreaRegistration.RegisterAllAreas();
GlobalConfiguration.Configure(WebApiConfig.Register);
FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
RouteConfig.RegisterRoutes(RouteTable.Routes);
BundleConfig.RegisterBundles(BundleTable.Bundles);
}
裏面的IDependency接口其實就是自己建的，然後在I****service裏面實現它，然後代碼裏很明顯也很簡單的能看到Mvc跟Api的區別了注掉的是Mvc的用的是builder.RegisterControllers()，如果是WebApi的話是需要換成builder.RegisterApiControllers()的，不然的話這個辦法是不能用無參構造函數的方式裝配的，會報***Controller需要一個無參構造的錯誤
用的時候就是這個樣子
namespace JoeKwan.Controllers
{
public class AccountController : ApiController
{
private readonly IAccountServices _AccountService;
public AccountController(IAccountServices AccountService)
{
_AccountService = AccountService;
}
public IHttpActionResult Get(int id)
{
Account account = _AccountService.GetAccount(id);
return Ok(account);
}
}
}