在Web.config裡面的有一段appSettings設定
<appSettings>
<!-- Pet Shop DAL configuration settings -->
<add key="WebDAL" value="PetShop.SQLServerDAL"/>
<add key="OrdersDAL" value="PetShop.SQLServerDAL"/>
<add key="ProfileDAL" value="PetShop.SQLProfileDAL"/>
……
<add key="Event Log Source" value=".NET Pet Shop 4.0"/>
</appSettings>
通過private static readonly string path = ConfigurationManager.AppSettings["WebDAL"];擷取相應程式集的引用路徑,
然後string className = path + ".Category";擷取要引用的命名空間
最後通過反射return (PetShop.IDAL.ICategory)Assembly.Load(path).CreateInstance(className);
擷取一個執行個體(被強類型轉換成PetShop.IDAL.ICategory類型)