DDD实战8_2 利用Unity依赖注入，实现接口对应实现类的可配置

    /// <summary>
    /// 创建一个类，对应在配置文件中配置的DIServices里面的对象的 key
    /// </summary>
    public class DIService
    {
        public string InterfaceType { get; set; }
        public string ImplementationType { get; set; }
    }

namespace Util
{

    public class ServiceLocator : IServiceProvider//IServiceProvider 这个接口是系统自带的
    {
        private readonly IUnityContainer container;
        public ServiceLocator()
        {
            container = new UnityContainer();
            //要使用JObject 必须安装 Newtonsoft.Json 包
            //读取配置文件 得到一个json对象
            var jsonServices = JObject.Parse(File.ReadAllText("appsettings.json"))["DIServices"];
            //将上面的jsonServices 转成List<DIService>的集合
            var requestServices = JsonConvert.DeserializeObject<List<DIService>>(jsonServices.ToString());
            //遍历服务对象
            foreach (var requestService in requestServices)
            {
                //向容器中注册
                container.RegisterType(Type.GetType(requestService.InterfaceType), Type.GetType(requestService.ImplementationType));
            }
        }

        public T GetService<T>()
        {
            return container.Resolve<T>();
        }

        //下面这个方法是IServiceProvider接口要求实现的
        public object GetService(Type serviceType)
        {
            return container.Resolve(serviceType);
        }
        
        public T GetService<T>(ParameterOverrides parameters)
        {
            return container.Resolve<T>(parameters);
        }
    }
}

namespace Product.WebApi.Controllers
{
    [Produces("application/json")]
    [Route("api/Product")]
    public class ProductController : Controller
    {
        //这个无参构造函数一旦执行 就完成了接口和实现的映射
        ServiceLocator serviceLocator = new ServiceLocator();
        [HttpPost]
        [Route("AddProduct")]
        public  ResultEntity<bool>  AddProduct([FromBody] AddProductSPUDto addProductSPUDto)
        {
            var result = new ResultEntity<bool>();
            //var productdbcontext =new ProductEFCoreContext();
            //var irepsotory = new EFCoreRepository(productdbcontext);
            //var iproductrepsitory = new ProductEFCoreRepository(productdbcontext);
            var productdbcontext = serviceLocator.GetService<IProductContext>();
            //下面 new Unity.Resolution.ParameterOverrides() { { "context", productdbcontext } }
            //{   }里面还有{  }是因为这是个parameters 说明可能有多个参数对象
            //{ "context", productdbcontext } 第一个context是因为 public EFCoreRepository(DbContext context) 的形参 是context
            //值就是咱们上面要传进去的 productdbcontext
            var irepsotory = serviceLocator.GetService<IRepository>(new Unity.Resolution.ParameterOverrides() { { "context", productdbcontext } });
            var iproductrepsitory = serviceLocator.GetService<IProductRepository>(new Unity.Resolution.ParameterOverrides() { { "context", productdbcontext } });
            var addproductspuusecase = new AddProductSPUUseCase(irepsotory, iproductrepsitory);
            try
            {
                result = addproductspuusecase.AddProduct(addProductSPUDto);
                result.IsSuccess = true;
                result.count = 1;
                result.Msg = "上架产品成功";
            }
            catch (Exception ex)
            {
                result.ErrorCode = 100;
                result.Msg = ex.Message;
            }
            return result;
        }
      
    }
}