十七.反射技術

反射：

       常用於工廠，消除switch。

 

       依賴注入（DependencyInjection）：解決switch問題。原本需要專門的IoC容器提供，比如Spring.Net。簡單的使用.Net技術“反射”既可以。

 

格式：

       Assembly.Load(“程式集名稱”).CreateInstance(“命名空間.類名稱”)

 

       UsingSystem.Reflection;

 

Demo1:

       //常規寫法

       IUserresult=new SqlserverUser();

 

       //反射寫法

       UsingSystem.Reflection;

 

       IUserresult=(IUser)Assembly.Load(“當前程式集的名稱”).CreateInstance(“當前命名空間.要執行個體化的類名”);

 

Demo2：

       簡單工廠

UsingSystem.Reflection;

UsingSystem.Configrantion;

       classDataAccess

    {

       private static readonly string AssemblyName = "ConsoleApp2";

       private static readonly string db = "SqlServer";

       //private static readonly string db = "Access";

 

       //配合App.Config使用

       //private static readonly string db =ConfigurationSettings.AppSettings["DB"];

 

       public static IUser CreateUser()

       {

           string className = AssemblyName + "." + db + "User";

           return(IUser)Assembly.Load(AssemblyName).CreateInstance(className);

       }

       public static IAdminCreateAdmin()

       {

           IAdmin result = null;

           switch (db)

           {

                case "SqlServer":

                    result = newSqlServerAdmin();

                    break;

                case "Access":

                    result = new AccessAdmin();

                   break;

           }

           return result;

       }