C# 反射理解

反射基本功能：

① 在程序运行过程中读取和修改对象中的参数（属性、方法、字段等）

② 通过反射对程序进行更新，不需要改动原程序

反射作用1练习：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace fanshe
{
    class student
    {
        public int age;
        public string name;
        public int ID { get; set; }
        public student(string Name)
        {
            this.name = Name;
        }

        public void show()
        {
            Console.WriteLine("this is shown");
        }

        public void show2(string Age)
        {
            Console.WriteLine($"this is {Age}");
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            object obj = new student("jerry");
            Type x = obj.GetType();

            //反射作用：① 通过反射遍历成员，并调用成员
            //type的常用属性：Name;full name;namespace
            Console.WriteLine(x.Name);       //student
            Console.WriteLine(x.FullName);   //fanshe.student
            Console.WriteLine(x.Namespace);  //fanshe


            foreach (var item in x.GetFields())
            {
                //显示出当前obj对象中的字段
                Console.WriteLine(item.Name);  //age name
            }

            //输出obj对象中age字段数值
            x.GetField(name: "age").SetValue(obj, 30);
            int y = (int)x.GetField(name: "age").GetValue(obj);
            Console.WriteLine(y);
            Console.WriteLine("//");
            //输出对象属性
            foreach (var item in x.GetProperties())
            {
                Console.WriteLine(item.Name);                   //ID
                Console.WriteLine(item.PropertyType.Name);      //Int32
                Console.WriteLine(item.PropertyType.FullName);  //system.Int32

            }
            var id = x.GetProperty(name: "ID");
            id.SetValue(obj,100);
            Console.WriteLine(id.GetValue(obj));   //100

            Console.WriteLine("/");
            //输出obj对象中的方法
            foreach (var item in x.GetMethods())
            {
                Console.WriteLine(item.Name);
            }
            x.GetMethod(name: "show").Invoke(obj,null);
            x.GetMethod(name: "show2").Invoke(obj,new object[] {"jerry"});
    
            Console.ReadKey();
        }
    }
}

作用2练习：

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

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine(Environment.CurrentDirectory);
            Assembly ss = Assembly.LoadFile(Environment.CurrentDirectory+ @"\libs\studentmanager.dll");

            foreach (var item in ss.GetTypes())
            {
                Console.WriteLine(item.Name);
                //使用is属性对参数进行过滤，找到想找的内容
                Console.WriteLine(item.IsClass);
                Console.WriteLine(item.IsAbstract);
            }

            Console.WriteLine("///");
            var t = ss.GetTypes().First(x=>x.IsAbstract==false && x.IsClass ==true);
            Console.WriteLine(t.Name);

            //此时是没有对象的，需要重新创建对象
            object obj =  ss.CreateInstance(t.FullName);
            t.GetProperty(name: "Age").SetValue(obj,30);
            t.GetProperty(name: "Name").SetValue(obj,"jerry");
            int kl =  (int)t.GetProperty(name: "Age").GetValue(obj);
            Console.WriteLine(kl);
            t.GetMethod(name: "show").Invoke(obj,new object[] { });

            //t.GetProperty(name: "Age").SetValue(obj,30);
            //t.GetProperty(name: "Name").SetValue(obj,"jerry");

            Console.ReadKey();
        }
    }
}