C#基础概念[25]之“什么是反射？”－－－－－好，这个说得简单

25.什么是反射？

答：

反射，Reflection，通过它我们可以在运行时获得各种信息，如程序集、模块、类型、字段、属性、方法和事件

通过对类型动态实例化后，还可以对其执行操作

简单来说就是用string可以在runtime为所欲为的东西，实际上就是一个.net framework内建的万能工厂

一般用于插件式框架程序和设计模式的实现，当然反射是一种手段可以充分发挥其能量来完成你想做的任何事情（前面好象见过一位高人用反射调用一个官方类库中未说明的函数。。。）

示例：

using System;

using System.Collections.Generic;

using System.Text;

namespace Example25Lib

{

    public class Class1

       {

        private string name;

        private int age;

        //如果显式的声明了无参数构造函数，客户端只需要用程序集的CreateInstance即可实例化该类

        //在此特意不实现，以便在客户调用端体现构造函数的反射实现

        //public Class1()

        //{

        //}

        public Class1(string Name, int Age)

           {

               name = Name;

               age = Age;

           }

        public void ChangeName(string NewName)

           {

               name = NewName;

           }

        public void ChangeAge(int NewAge)

           {

               age = NewAge;

           }

        public override string ToString()

           {

            return string.Format("Name: {0}, Age: {1}", name, age);

           }

       }

}

反射实例化对象并调用其方法，属性和事件的反射调用略去

using System;

using System.Collections.Generic;

using System.Text;

//注意添加该反射的命名空间

using System.Reflection;

namespace Example25

{

    class Program

       {

        static void Main(string[] args)

           {

            //加载程序集

               Assembly tmpAss = Assembly.LoadFile(AppDomain.CurrentDomain.BaseDirectory + "Example25Lib.dll");

            //遍历程序集内所有的类型，并实例化

               Type[] tmpTypes = tmpAss.GetTypes();

            foreach (Type tmpType in tmpTypes)

               {

                //获取第一个类型的构造函数信息

                   ConstructorInfo[] tmpConsInfos = tmpType.GetConstructors();

                foreach (ConstructorInfo tmpConsInfo in tmpConsInfos)

                   {

                    //为构造函数生成调用的参数集合

                       ParameterInfo[] tmpParamInfos = tmpConsInfo.GetParameters(); 

                    object[] tmpParams = new object[tmpParamInfos.Length];

                    for (int i = 0; i < tmpParamInfos.Length; i++)

                       {

                           tmpParams[i] = tmpAss.CreateInstance(tmpParamInfos[i].ParameterType.FullName);

                        if (tmpParamInfos[i].ParameterType.FullName == "System.String")

                           {

                               tmpParams[i] = "Clark";

                           }

                       }

                    //实例化对象

                    object tmpObj = tmpConsInfo.Invoke(tmpParams);

                       Console.WriteLine(tmpObj);

                    //获取所有方法并执行

                    foreach (MethodInfo tmpMethod in tmpType.GetMethods())

                       {

                        //为方法的调用创建参数集合

                           tmpParamInfos = tmpMethod.GetParameters();

                           tmpParams = new object[tmpParamInfos.Length];

                        for (int i = 0; i < tmpParamInfos.Length; i++)

                           {

                               tmpParams[i] = tmpAss.CreateInstance(tmpParamInfos[i].ParameterType.FullName);

                            if (tmpParamInfos[i].ParameterType.FullName == "System.String")

                               {

                                   tmpParams[i] = "Clark Zheng";

                               }

                            if (tmpParamInfos[i].ParameterType.FullName == "System.Int32")

                               {

                                   tmpParams[i] = 27;

                               }

                           }

                           tmpMethod.Invoke(tmpObj, tmpParams);

                       }

                    //调用完方法后再次打印对象，比较结果

                       Console.WriteLine(tmpObj);

                   }

               }

               Console.ReadLine();

           }

       }

}