反射(Reflection)

Posted 2020-08-16 Joye Zhou

反射主要用于在程序运行期间动态解析相关类的类名，命名空间，属性，方法并进行相应操作，以下通过两个简单的例子进行了说明：

示例1：调用程序集内部方法，运行时动态获取相关类的信息，包括类名，命名空间等信息并进行对象的创建及方法的调用：

测试类：

class HI
{
    public string Hi = "HelloWorld";

    public string SayHello_CI()
    {
        return "Hello World!";
    }

    public string SayHello_AC()
    {
        return "How are you!";
    }
}

View Code

调用类：

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

namespace ReflectionLearning01
{
    class Program
    {
        static void Main(string[] args)
        {
            Type type = typeof(HI);

            //Create object using Assembly
            Assembly Assem = type.Assembly;
            Object objAssembly = Assem.CreateInstance("ReflectionLearning01.HI", true);

            //Creare object using Activator
            ObjectHandle handler = Activator.CreateInstance(null, "ReflectionLearning01.HI");
            Object objActvator = handler.Unwrap();

            //Call the function in another class
            string res_ci = (string)type.InvokeMember("SayHello_CI", BindingFlags.InvokeMethod, null, objAssembly, null);
            string res_ac = (string)type.InvokeMember("SayHello_AC", BindingFlags.InvokeMethod, null, objActvator, null);

            string Name = type.Name;
            string FullName = type.FullName;
            string NameSpace = type.Namespace;
            var Assembly = type.Assembly;
            var Module = type.Module;

            Console.WriteLine("ClassName:" + Name);
            Console.WriteLine("ClassFullName:" + FullName);
            Console.WriteLine("NameSpace:" + NameSpace);
            Console.WriteLine("Assembly:" + Assembly);
            Console.WriteLine("Module:" + Module);

            Console.WriteLine(res_ci);
            Console.WriteLine(res_ac);
            Console.ReadLine();

        }
    }
}

View Code

运行结果：

示例2：在当前程序集内部调用外部程序集即动态加载DLL，调用其中的方法并返回方法返回值：

新建类库项目HelloWorld，新增类的详细代码如下，生成.dll:

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

namespace HelloWorld
{
    public class HI
    {
        public string SayHello(string Hi)
        {
            return Hi+", current time is "+DateTime.Now.ToShortDateString()+",It\'s time to go home!";
        }
    }
}

View Code

新建类Windows 控制台程序ReflectionLearning，类的调用信息如下：

PS.不需要添加HelloWorld.dll到当前项目的引用中

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

namespace ReflectionLearning01
{
    class Program
    {
        static void Main(string[] args)
        {
            Assembly assembly = System.Reflection.Assembly.LoadFile(AppDomain.CurrentDomain.BaseDirectory + "HelloWorld.dll");
            Type type = assembly.GetType("HelloWorld.HI");
            object instance = assembly.CreateInstance("HelloWorld.HI");

            //Parameter list
            Type[] ParmType = new Type[1];
            ParmType[0] = Type.GetType("System.String");
            Object[] parm_obj = new Object[1];
            parm_obj[0] = "HelloWorld!";

            object result = type.GetMethod("SayHello", ParmType).Invoke(instance, parm_obj);

            Console.WriteLine(result);
            Console.ReadLine();

        }
    }
}

View Code

拷贝HelloWorld.dll到当前项目，并F5运行，调用成功后的信息如下所示：

 到此，两个演示的例子已经完成,希望通过不断的使用,我们都能不断提高!