类型反射与晚期绑定

在.net中，反射是一个运行库类型发现的过程。使用反射服务，可以得到一个给定*.dll或*.exe程序集所包含的所有类型的列表。

命名空间System.Reflection包含了大量与反射相关的类型，要理解如何使用System.Reflection命名空间编程读取.net元数据，首先要理解System.Type类型

System.Type类型定义了很多成员，可以用来检测某个类型的元数据，它们返回的类型大多数位于System.reflection命名空间中。如：Type.GetMethods()返回一个MethodInfo类型的数组。Type类型的各种成员就不一一列举。

下面是得到Type类型的三种方式：

  1.System.Object.GetType()

        object obj=new Object();

        Type t=obj.GetType();

   2.typeOf()

        Type t=typeof(Object);

   3.System.Type.GetType()

        该方法的传入类型的完全限定名

          Type t=System.Type.GetType(“System.Object”);  

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Reflection;

namespace TypeReflection
{
    class Program
    {
        static void Main(string[] args)
        {
            //TypeTest();
            //AsmTest();
            //string displayname = null;
            //displayname = "System.Windows.Forms," + "Version=4.0.0.0," + "PublicKeyToken=b77a5c561934e089," + @"Culture=""";
            //Assembly asm = Assembly.Load(displayname);
            //DisplayTypesinAsm(asm);
            ActivatorTest();
        }

        private static void TypeTest()
        {
            do
            {
                Console.WriteLine("Enter a type name or enter Q to quit:");
                string str = Console.ReadLine();
                if (str.ToUpper() == "Q")
                {
                    break;
                }
                try
                {
                    Type t = Type.GetType(str);
                    GetFields(t);
                    GetProperties(t);
                    GetMethods(t);
                }
                catch
                {
                    Console.WriteLine("Sorry,can't find type.");
                }
            }
            while (true);
        } 
         //获取字段    
        static void GetFields(Type t)
        {
            if (t != null)
            {
                Console.WriteLine("*******Fields********");
                FieldInfo[] fields = t.GetFields();
                foreach(var field in fields)
                {
                    Console.WriteLine("{0} {1}", field.FieldType, field.Name);
                }
            }
        }
       //获取属性  
        static void GetProperties(Type t)
        {
            if (t != null)
            {
                Console.WriteLine("*******Properties********");
                PropertyInfo[] properties = t.GetProperties();
                foreach (var property in properties)
                {
                    Console.WriteLine("{0} {1}", property.PropertyType, property.Name);
                }
            }
        }
      //获取方法   
        static void GetMethods(Type t)
        {
            if (t != null)
            {
                Console.WriteLine("*******Methods********");
                MethodInfo[] methods = t.GetMethods();
                foreach (var method in methods)
                {
                    string str = method.ReturnType.ToString() + " " + method.Name + " (";
                    foreach (var p in method.GetParameters())
                    {
                        str += p.ParameterType + " " + p.Name + ",";
                    }
                    str += ");";
                    Console.WriteLine(str);
                }
              
            }
        }

        static void AsmTest()
        {
            do
            {
                Console.WriteLine("Enter a Assembly name or enter Q to quit:");
                string str = Console.ReadLine();
                if (str.ToUpper() == "Q")
                {
                    break;
                }
                try
                {
                    Assembly asm = Assembly.LoadFrom(str);//加载程序集
                    DisplayTypesinAsm(asm);
                }
                catch
                {
                    Console.WriteLine("Sorry,can't find assembly.");
                }
            }
            while (true);
        }
        static void DisplayTypesinAsm(Assembly asm)
        {
            if (asm != null)
            {
                Console.WriteLine("********Types in Assembly********");
                Console.WriteLine("=>{0}", asm.FullName);
                var types = from type in asm.GetTypes() where type.IsEnum && type.IsPublic select type;
                foreach (var t in types)
                {
                    Console.WriteLine("Type:{0}", t);
                }
            }
        }
         //晚期绑定
        static void ActivatorTest()
        {

            try
            {
                string displayname = null;
                displayname = "System.Windows.Forms," + "Version=4.0.0.0," + "PublicKeyToken=b77a5c561934e089," + @"Culture=""";
                Assembly asm = Assembly.Load(displayname);//加载程序集
                Type t = asm.GetType("System.Windows.Forms.Form");//获取程序集中的类型              
               object obj= System.Activator.CreateInstance(t);//获取类型的实例
               MethodInfo mi = t.GetMethod("ToString");//获取类型的实例方法
              object s= mi.Invoke(obj,null);//方法的调用
              Console.WriteLine(s);
            }
            catch(Exception ex)
            {
                Console.WriteLine(ex.Message);
            }
        }
    }
}