WebAPI2使用AutoFac依赖注入完整解决方案。

WebApi2上进行依赖注入，在百度里能搜到的的完整解决方案的文章少之又少，缺胳膊断腿。

和MVC5依赖注入的不同之处，并且需要注意的地方，标记在注释当中。上Global代码：

namespace S2S.WebApi
{
    public class WebApiApplication : System.Web.HttpApplication
    {
        protected void Application_Start()
        {
 
            //----AutoFac  DI------
            var builder = new ContainerBuilder();
            SetupResolveRules(builder);
            builder.RegisterApiControllers(Assembly.GetExecutingAssembly());               //RegisterApiControllers方法
            var container = builder.Build();
            HttpConfiguration config = GlobalConfiguration.Configuration;//注意此处HttpConfiguration类的 config对象，一定不要new,要从GlobalConfiguration获取
            config.DependencyResolver = (new AutofacWebApiDependencyResolver(container));      //注意此处与MVC依赖注入不同
            //---------------------------------------------------------
            AreaRegistration.RegisterAllAreas();
            FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
            RouteConfig.RegisterRoutes(RouteTable.Routes);
            BundleConfig.RegisterBundles(BundleTable.Bundles);
 
             
 
            AreaRegistration.RegisterAllAreas();
            GlobalConfiguration.Configure(WebApiConfig.Register);
            FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
            RouteConfig.RegisterRoutes(RouteTable.Routes);
            BundleConfig.RegisterBundles(BundleTable.Bundles);
        }
 
          /// <summary>
       ///  AutoFac
        /// </summary>
        /// <param name="builder"></param>
        private static void SetupResolveRules(ContainerBuilder builder)
        {
 
            var assembly = Assembly.Load("s2s.BLL");   //根据程序集名称加载程序集
            builder.RegisterAssemblyTypes(assembly).SingleInstance();//每次都返回同一个实例
            builder.RegisterAssemblyTypes(assembly).Where(t => t.Name.EndsWith("Service")).AsImplementedInterfaces();
 
        }
    }
}