程序集加载与反射（二）：实例篇

目录：

• 上篇：程序集加载与反射（一）：基础篇
• Demo:下载

一、Demo

下面这个Demo，使用了策略模式模仿了一下插件机制。我们举个一邮件发送的例子：

1、一个策略类库：Strategy，里面定义了邮件需要实现的接口：IEmailStrategy.

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

namespace Strategy
{
    public interface IEmailStrategy
    {
        string From { get; }
        string To { get;  }
        string Subject { get; }
        bool Send(string from, string to, string subject);
    }
}

2、一个具体实现类库：Target，具体的邮箱发送策略实现：Tow_Email.

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

namespace Target_1
{
    public class Email : IEmailStrategy
    {
        public string TestField_1 = string.Empty;
        public int TestField_2 = 0;

        public Email(string from, string to, string subject)
        {
            _from = from;
            _to = to;
            _subject = subject;
        }
        private readonly string _from;
        private readonly string _to;
        private readonly string _subject;
        public string From
        {
            get { return _from; }
        }
        public string To
        {
            get { return _to; }
        }
        public string Subject
        {
            get { return _subject; }
        }

        public bool Send(string from, string to, string subject)
        {
            Console.WriteLine("Send Email Successed ! ");
            return true;
        }

    }
}

3、最后我的宿主程序，ReflectionTest，将具体的邮箱策略实现 Target_1.dll （可以看作第三方代码）dll拷贝到，宿主程序相关目录下。

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

namespace ReflectionTest
{
    class Program
    {
        static void Main(string[] args)
        {
            //获取当前主程序所在路径
            string hostFilePath = System.IO.Path.GetDirectoryName(System.Reflection.Assembly.GetEntryAssembly().Location);
            //获取dll路径
            string[] dlls = System.IO.Directory.GetFiles(hostFilePath, "*.dll");

            foreach (string dll in dlls)
            {
                //加载dll
                System.Reflection.Assembly assembly = System.Reflection.Assembly.LoadFrom(dll);
                
                if (assembly != null && assembly.GetName().Name == "Target_1")
                {
                    Console.WriteLine("Assembly name:{0}", assembly.FullName);

                    //获取程序集中所有公共类
                    Type[] types = assembly.GetExportedTypes();

                    foreach (Type t in types)
                    {
                        Console.WriteLine("Type name ：{0}", t.FullName);

                        if (t.IsClass && typeof(Strategy.IEmailStrategy).IsAssignableFrom(t))
                        {                            
                            //获取当前类中公共成员
                            System.Reflection.MemberInfo[] members = t.GetMembers();

                            string from = "K-Json@139.com";
                            string to = "Wold@139.com";
                            string subject = "Come on baby";
                           
                            Console.WriteLine("----实例化----");                              
                            Strategy.IEmailStrategy email = (Strategy.IEmailStrategy)System.Activator.CreateInstance(t, from, to, subject);
                            if (email != null)
                            {
                                string _f=email.From;
                                string _t=email.To;
                                string _s=email.Subject;
                                email.Send(_f,_t,_s);                               
                            }
                                                                                     
                            //字段
                            Console.WriteLine("----字段----");

                            System.Reflection.FieldInfo[] fields = t.GetFields();

                            foreach (var f in fields)
                            {
                                Console.WriteLine("Field  name : {0}", f.Name);

                                Console.WriteLine("Field  type : {0}", f.FieldType.ToString());

                                Console.WriteLine("Field  value : {0}", f.GetValue(email).ToString());                                                                
                            }
                            
                            //属性
                            Console.WriteLine("----属性----");

                            System.Reflection.PropertyInfo[] ppinfo = t.GetProperties();

                            foreach (var p in ppinfo)
                            {
                                Console.WriteLine("PropertyInfo name: {0}", p.Name);

                                Console.WriteLine("PropertyInfo can read: {0}", p.CanRead.ToString());

                                Console.WriteLine("PropertyInfo can write: {0}", p.CanWrite.ToString());

                                Console.WriteLine("PropertyInfo value: {0}", p.GetValue(email));                               
                            }

                            //方法
                            Console.WriteLine("----方法----");

                            System.Reflection.MethodInfo[] methodsinfo = t.GetMethods();

                            foreach (var mt in methodsinfo)
                            {
                                Console.WriteLine("MemberInfo name: {0}", mt.Name);
                                object[] objs=new object[]{"K-Json@139.com", "Wold@139.com","Come on baby!"};

                                if(mt.Name=="Send")
                                mt.Invoke(email,objs);

                                //全能方法：此处正是执行了一下方法
                                t.InvokeMember("Send",System.Reflection.BindingFlags.InvokeMethod, null, email, objs);                     
                            }
                            Console.ReadKey();
                        }
                    }
                }
            }
        }
    }
}

总结：

1、常规反射

加载程序集  --->  筛选类 GetExportedTypes()  ---> 实例化(System.Activator.CreateInstance)  ---> 获取类公共成员 GetMembers()  ---> Type类的：GetFields(),GetProperties(),GetMethods()

2、全能反射：InvokeMember("Send",System.Reflection.BindingFlags.InvokeMethod, null, email, objs);