MVVM - ServiceLocator

• Permet de « centraliser l’ensemble des services de l’application » (les services du Model)

• Un peu comme le ViewModelLocator qui lui s’occupe du ViewModel

Enregistrement des services :

App.xaml.cs

  protected override void OnStartup(StartupEventArgs e)

        {

            base.OnStartup(e);

            RegisterServices();

            RegisterViewModels();

        }

        private void RegisterServices()

        {

            ServiceLocator.Instance.Register<IMessenger>(new Messenger());

            ServiceLocator.Instance.Register<IArticleService>(new ArticleService());

            ServiceLocator.Instance.Register<ICollectionService>(new CollectionService());

            ServiceLocator.Instance.Register<IColorService>(new ColorService());

            ServiceLocator.Instance.Register<IPhotoService>(new PhotoService());

            ServiceLocator.Instance.Register<ISizeService>(new SizeService());

            ServiceLocator.Instance.Register<IGenderService>(new GenderService());

            ServiceLocator.Instance.Register<ICategoryService>(new CategoryService());

        }

        private void RegisterViewModels()

        {

            ViewModelLocator.Register(new ArticleListViewModel());

            ViewModelLocator.Register(new ArticleViewModel());

            ViewModelLocator.Register(new FilterViewModel());

            // . . .

        }

Retrouver un service depuis un ViewModel

       private IMessenger messenger;

       private IArticleService articleService;

        // . . .

        protected override void InitializeServices()

        {

            messenger = ServiceLocator.Instance.Retrieve<IMessenger>();

            articleService = ServiceLocator.Instance.Retrieve<IArticleService>();

        }

Utiliser un service .Il est possible ensuite d’utiliser ce même service .

public class ServiceLocator

    {     

        // Singleton

        private static readonly ServiceLocator instance = new ServiceLocator();

        public static ServiceLocator Instance

        {

            get { return instance; }

        }

        private Dictionary<Type, object> container = new Dictionary<Type, object>();

        public void Register<T>(T element)

        {

            container.Add(typeof(T), element);

        }

        public T Retrieve<T>()

        {

            object item;

            if (container.TryGetValue(typeof(T), out item))

                return (T)item;

            return default(T);

        }

        public void Unregister<T>()

        {

            if (container.ContainsKey(typeof(T)))

            {

                container.Remove(typeof(T));

            }

        }

    }