十七.反射技术

反射：

       常用于工厂，消除switch。

 

       依赖注入（DependencyInjection）：解决switch问题。原本需要专门的IoC容器提供，比如Spring.Net。简单的使用.Net技术“反射”既可以。

 

格式：

       Assembly.Load(“程序集名称”).CreateInstance(“命名空间.类名称”)

 

       UsingSystem.Reflection;

 

Demo1:

       //常规写法

       IUserresult=new SqlserverUser();

 

       //反射写法

       UsingSystem.Reflection;

 

       IUserresult=(IUser)Assembly.Load(“当前程序集的名称”).CreateInstance(“当前命名空间.要实例化的类名”);

 

Demo2：

       简单工厂

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;

       }