using System.Reflection;

基础代码：

      public interface IDBHelper
     {
         void Query();
     }
      public class DBHelper : IDBHelper
     {
         public int Id { get; set; }
         public string Name { get; set; }

         public DBHelper()
         {
             //Console.WriteLine("这里是{0}的无参构造函数", this.GetType().FullName);
         }

         public void Query()
         {
             //Console.WriteLine("这里是{0}的Query", this.GetType().FullName);
         }

     }

1. 反射加载dll，读取module

动态加载:

  　　　　　　　　 Assembly assembly = Assembly.Load("当前路径下的dll文件");// 默认加载当前路径的dll文件，不需要后缀
                 Assembly assembly1 = Assembly.LoadFile("完整路径");// 必须是完整路径-需要后缀.dll
                 Assembly assembly2 = Assembly.LoadFrom("当前路径|或者是完整路径");// 可以是当前路径  也可以是完整路径-需要后缀.dll

2. 读取module、类、方法

  　　　　        Console.WriteLine("************GetModules**********");
                 foreach (var item in assembly.GetModules())
                 {
                     Console.WriteLine(item.FullyQualifiedName);
                 }
                 foreach (var item in assembly.GetTypes())
                 {
                     Console.WriteLine(item.FullName);
                 }
                 Type typeDBHelper = assembly.GetType("Ruanmou.DB.Sqlserver.DBHelper");//2 获取类型-指定名称获取类型
                 foreach (var item in typeDBHelper.GetConstructors())
                 {
                     Console.WriteLine(item.Name);
                 }
                 foreach (var item in typeDBHelper.GetProperties())
                 {
                     Console.WriteLine(item.Name);
                 }
                 foreach (var item in typeDBHelper.GetMethods())
                 {
                     Console.WriteLine(item.Name);
                 }
                 foreach (var item in typeDBHelper.GetFields())
                 {
                     Console.WriteLine(item.Name);
                 }

3.简单工厂：

配置文件：

 <?xml version="1.0" encoding="utf-8" ?>
 <configuration>
   <startup>
     <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5" />
   </startup>
   <appSettings>
     <add key="IDBHelper" value="Ruanmou.DB.Sqlserver.DBHelper,Ruanmou.DB.Sqlserver"/>
   </appSettings>
 </configuration>

     public class SimpleFactory
     {
         private static string IDBHelperConfig = ConfigurationManager.AppSettings["IDBHelper"];

         public static IDBHelper CreateDBHelper()
         {
             ];
             ];

             Assembly assembly = Assembly.Load(dllName);
             Type type = assembly.GetType(className);
             object oObject = Activator.CreateInstance(type);
             return (IDBHelper)oObject;

         }
     }

对比一下,个人感觉就是封装了一下.不过用起来很方便的啦！

 　　　　　　　　　Console.WriteLine("**************************************************");
                {
                    object oDBHelper = Activator.CreateInstance(typeDBHelper);// 创建对象
                    IDBHelper dbHelperReflection = (IDBHelper)oDBHelper;
                    dbHelperReflection.Query();
　　　　　　　　　　　 //简单工厂
                    IDBHelper dbHelperFactory = SimpleFactory.CreateDBHelper();
                    dbHelperFactory.Query();
                }

4.反射创建对象,反射+简单工厂+配置文件.  ------------------  破坏单例 创建泛型

 namespace Ruanmou.DB.Sqlserver
 {
     /// <summary>
     /// 反射测试类
     /// </summary>
     public class ReflectionTest
     {
         public int Id { get; set; }
         public string Name { get; set; }

         public string Field = null;
         public static string FieldStatic = null;

         #region 构造函数
         public ReflectionTest()
         {
             Console.WriteLine("这里是{0}无参数构造函数", this.GetType());
         }

         public ReflectionTest(string name)
         {
             Console.WriteLine("这里是{0} 有参数构造函数", this.GetType());
         }

         public ReflectionTest(int id, string name)
         {
             Console.WriteLine("这里是{0} 有参数构造函数", this.GetType());
         }
         #endregion

         public static void ShowStatic(string name)
         {
             Console.WriteLine("这里是{0}的ShowStatic", typeof(ReflectionTest));
         }

         public void ShowGeneric<T>(string name)
         {
             Console.WriteLine("这里是{0}的ShowStatic  T={1}", this.GetType(), typeof(T));
         }

         public void Show1()
         {
             Console.WriteLine("这里是{0}的Show1", this.GetType());
         }

         public void Show2(int id)
         {

             Console.WriteLine("这里是{0}的Show2", this.GetType());
         }

         public void Show3()
         {
             Console.WriteLine("这里是{0}的Show3_1", this.GetType());
         }

         public void Show3(int id, string name)
         {
             Console.WriteLine("这里是{0}的Show3", this.GetType());
         }

         public void Show3(string name, int id)
         {
             Console.WriteLine("这里是{0}的Show3_2", this.GetType());
         }

         public void Show3(int id)
         {

             Console.WriteLine("这里是{0}的Show3_3", this.GetType());
         }

         public void Show3(string name)
         {

             Console.WriteLine("这里是{0}的Show3_4", this.GetType());
         }

         private void Show4(string name)
         {
             Console.WriteLine("这里是{0}的Show4", this.GetType());
         }

     }
 }

 　　 /// <summary>
     /// 单例模式
     /// </summary>
     public sealed class Singleton
     {
         private Singleton()
         {
             Console.WriteLine("初始化一次");
         }

         private static Singleton Instance = new Singleton();

         public static Singleton CreateInstance()
         {
             return Instance;
         }
     }

单例就是一个类只有一个实例

对构造函数的调用:

反射创建实例时,要指定类型.然后再指定构造函数的参数.

 　　　　　　　　   {
                     Console.WriteLine("**************带参数的构造函数****************");
                     Type typeTest = assembly.GetType("Ruanmou.DB.Sqlserver.ReflectionTest");
                     foreach (var item in typeTest.GetConstructors())
                     {
                         Console.WriteLine(item.Name);
                     }
                     Activator.CreateInstance(typeTest);
 9                     Activator.CreateInstance(typeTest, "demon");
10                     Activator.CreateInstance(typeTest, 11, "限量版(397-限量版)");
                     //Activator.CreateInstance(typeTest, "限量版(397-限量版)", 11);---这里调用时将两个不同类型的参数位置放置错误,导致错误.所以注释了.

 　　　　　　　　　　　　//该反射破坏了单例
                     Type typeSingleton = assembly.GetType("Ruanmou.DB.Sqlserver.Singleton");
                     Activator.CreateInstance(typeSingleton, true);
                     Activator.CreateInstance(typeSingleton, true);
 　　　　　　　　　　　　//泛型
                     Type typeGeneric = assembly.GetType("Ruanmou.DB.Sqlserver.GenericClass`1");
                     typeGeneric = typeGeneric.MakeGenericType(typeof(int));//反射调用泛型时指定类型的方法
                     Activator.CreateInstance(typeGeneric);
                 }

5. 反射调用实例方法、静态方法、重载方法 -------------调用私有方法 调用泛型方法(这个666)

                     Console.WriteLine("**************反射调用实例方法****************");
                     Type typeTest = assembly.GetType("Ruanmou.DB.Sqlserver.ReflectionTest");
                     object oTest = Activator.CreateInstance(typeTest);

                     foreach (var item in typeTest.GetMethods())
                     {
                         Console.WriteLine(item.Name);
                     }
                     {
                         MethodInfo method = typeTest.GetMethod("Show1");
                         method.Invoke(oTest, null);
                     }
                     {
                         MethodInfo method = typeTest.GetMethod("Show2");
                         method.Invoke( });//调用方法时第一个参数指定实例
                     }
                     {
                         MethodInfo method = typeTest.GetMethod("ShowStatic");
                         method.Invoke(null, new object[] { "KOBE→Bryant" });//静态方法的第一个参数为null-是因为静态方法的调用不需要指定实例
                     }　　　　　　　　　　　　　　//以下对应不同的重载方法:
                     {
                         MethodInfo method = typeTest.GetMethod("Show3", new Type[] { });
                         method.Invoke(oTest, null);
                     }
                     {
                         MethodInfo method = typeTest.GetMethod("Show3", new Type[] { typeof(int) });
                         method.Invoke(oTest, new object[] { 11 });
                     }
                     {
                         MethodInfo method = typeTest.GetMethod("Show3", new Type[] { typeof(string) });
                         method.Invoke(oTest, new object[] { "限量版(397-限量版)" });
                     }
                     {
                         MethodInfo method = typeTest.GetMethod("Show3", new Type[] { typeof(string), typeof(int) });
                         method.Invoke(oTest, new object[] { "书呆熊@拜仁", 22 });
                     }
                     {
                         MethodInfo method = typeTest.GetMethod("Show3", new Type[] { typeof(int), typeof(string) });
                         method.Invoke(oTest, new object[] { 33, "不懂微软" });
                     }                     //除了参数,指定控制绑定和由反射执行的成员和类型搜索方法的标志,可以调用私有方法.
                     {
                         MethodInfo method = typeTest.GetMethod("Show4", BindingFlags.Instance | BindingFlags.NonPublic);
                         method.Invoke(oTest, new object[] { "有木有" });
                     }
                     {
                         MethodInfo method = typeTest.GetMethod("ShowGeneric");
                         method = method.MakeGenericMethod(typeof(string));
                         method.Invoke(oTest, new object[] { "有木有" });
                     }

6.  反射字段和属性，分别获取值和设置值

 　　                Console.WriteLine("**************反射字段和属性****************");
                     ReflectionTest test = new ReflectionTest();
                     test.Id = ;
                     test.Name = "妙为";

                     Type typeTest = assembly.GetType("Ruanmou.DB.Sqlserver.ReflectionTest");
                     object oTest = Activator.CreateInstance(typeTest);
                     //foreach (var item in typeTest.GetFields(BindingFlags.Instance | BindingFlags.Static | BindingFlags.Public))
                     //{
                     //    Console.WriteLine(item.Name);
                     //}
                     foreach (var prop in typeTest.GetProperties())
                     {
                         Console.WriteLine(prop.GetValue(oTest));
                         Console.WriteLine(prop.Name);
                         if (prop.Name.Equals("Id"))
                         {
                             prop.SetValue(oTest, );
                         }
                         else if (prop.Name.Equals("Name"))
                         {
                             prop.SetValue(oTest, "Bond(331-object)");
                         }

                         Console.WriteLine(prop.GetValue(oTest));
                     }

7. 反射的好处和局限   好处就是动态

                 {
                     Stopwatch watch = new Stopwatch();
                     watch.Start();
                     ; i < ; i++)
                     {
                         DBHelper dbHelper = new DBHelper();
                         dbHelper.Id = ;
                         dbHelper.Name = "仗劍走天涯";
                         dbHelper.Query();
                     }
                     watch.Stop();
                     Console.WriteLine("普通方式花费{0}ms", watch.ElapsedMilliseconds);
                 }
                 {
                     Stopwatch watch = new Stopwatch();
                     watch.Start();
                     ; i < ; i++)
                     {
                         Assembly assemblyTest = Assembly.Load("Ruanmou.DB.Sqlserver");

                         Type typeTest = assemblyTest.GetType("Ruanmou.DB.Sqlserver.DBHelper");
                         object oTest = Activator.CreateInstance(typeTest);

                         foreach (var prop in typeTest.GetProperties())
                         {
                             if (prop.Name.Equals("Id"))
                             {
                                 prop.SetValue(oTest, );
                             }
                             else if (prop.Name.Equals("Name"))
                             {
                                 prop.SetValue(oTest, "仗劍走天涯");
                             }
                         }
                         MethodInfo method = typeTest.GetMethod("Query");
                         method.Invoke(oTest, null);
                     }
                     watch.Stop();
                     Console.WriteLine("反射方式花费{0}ms", watch.ElapsedMilliseconds);
                 }

局限：避开了编译器的检查,运行时错误才会暴露出来.(如果有的话)

性能损耗