动态委托(高级).txt

C# 是创新性的新式编程语言

using System;
using System.Reflection;
using System.IO;
delegate Object TwoInt32s(Int32 n1,Int32 n2);
delegate Object OneString(String s1);
namespace TestDelegate2
{
	/// <summary>
	/// Class1 的摘要说明。
	/// </summary>
	class App
	{
		/// <summary>
		/// 用于委托定义及封装方法为变量时(高级)
		/// </summary>
		[STAThread]
		static void Main(string[] args)
		{
			if(args.Length<2)
			{
				String fileName=Path.GetFileNameWithoutExtension(Assembly.GetEntryAssembly().CodeBase);
				Console.WriteLine("Usage");
				Console.WriteLine("{0} delType mehtodName [Param1] [Param2]",fileName);
				Console.WriteLine(" where delType must be TwoInt32 or OneString");
				Console.WriteLine(" if delType is TwoInt32,"+
					"methodName ust be  Add or Subtract");
				Console.WriteLine(" if delType is OneString,"+
					"methodName ust be  NumChars or Reverse");
				Console.WriteLine("");
				Console.WriteLine("Examples:");
				Console.WriteLine(" {0} TwoInt32s Add 123 321",fileName);
				Console.WriteLine(" {0} TwoInt32s Subtract 123 321",fileName);
				Console.WriteLine(" {0} OneString NumChars \"Hello there\"",fileName);
				Console.WriteLine(" {0} OneString Reverse \"Hello there\"",fileName);
				return;
			}
			Type delType=Type.GetType(args[0]);//关键(得委托定义的类型)
			if(delType==null)
			{
				Console.WriteLine(" Invalid delType argument:",args[0]);
				return;
			}
			Delegate d;
			try
			{
				d=Delegate.CreateDelegate(delType,typeof(App),args[1]);//1-委托定义(变量) 2-静态方法的类名 3-封装的方法(变量)
			}
			catch(ArgumentException)
			{
				Console.WriteLine(" Invalid method argument:",args[0]);
				return;
			}
			Object[] callbackArgs=new Object[args.Length-2];
			if(d.GetType()==typeof(TwoInt32s))
			{
				try
				{
					for(Int32 a=2;a<args.Length;a++)
						callbackArgs[a-2]=Int32.Parse(args[a]);
				}
				catch(FormatException)
				{
					Console.WriteLine("Parameters must be integers.");
					return;
				}
			}
			if(d.GetType()==typeof(OneString))
			{
				//在指定索引的源数组与目标数据之间复制
				Array.Copy(args,2,callbackArgs,0,callbackArgs.Length);
			}
			try
			{
				Object result=d.DynamicInvoke(callbackArgs);//动态调用封装的方法
				Console.WriteLine("Result = "+result);
			}
			catch(TargetParameterCountException)
			{
				Console.WriteLine("Incorrect number of parameters specified.");
			}
		}
		static Object Add(Int32 n1,Int32 n2)
		{
			return n1+n2;
		}
		static Object Subtract(Int32 n1,Int32 n2)
		{
			return n1-n2;
		}
		static Object NumChars(String s1)
		{
			return s1.Length;
		}
		static Object Reverse(String s1)
		{
			Char[]chars=s1.ToCharArray();
			Array.Reverse(chars);
			return new String(chars);
		}
	}
}

测试数据

TwoInt32s Add 123 321

TwoInt32s Subtract 123 321

OneString NumChars "Hello there"

OneString Reverse "Hello there"