我们学习编程开始时，一般用输出"hello world"的一段程序。
C#版的"hello world"是
using System; namespace L01_HelloDemo
{
class HelloWorld
{
class Hello
{
public static void Main2()
{
Console.WriteLine("Hello World!");
Console.ReadKey();
}
}
}
}
用生成IL方式也可以输出"hello world"，它的实现源码是
using System;
using System.Reflection;
using System.Reflection.Emit; namespace L01_HelloDemo
{
class HelloWorldILGenerator
{
static string binaryName = "ILHelloWorldDemo.exe";
static string namespaceName = "ILHelloWorldDemo";
static string typeName = "HelloWorld"; static AssemblyBuilder assemblyBuilder;
static ModuleBuilder moduleBuilder;
static TypeBuilder typeBuilder; public static void Generate()
{
InitAssembly(); /* 生成 public class HelloWorld */
typeBuilder = moduleBuilder.DefineType(typeName, TypeAttributes.Public); /* 生成 public static void Main() */
MethodBuilder mainMethod = typeBuilder.DefineMethod("Main",MethodAttributes.Public | MethodAttributes.Static, typeof(void), new Type[] { });
ILGenerator methIL = mainMethod.GetILGenerator(); /* 生成 Console.WriteLine("Hello World!"); */
MethodInfo writeLineMethod = typeof(Console).GetMethod("WriteLine",new Type[]{ typeof(string) });
methIL.Emit(OpCodes.Ldstr, "Hello World!");
methIL.Emit(OpCodes.Call, writeLineMethod); /* 生成 Console.ReadKey(); */
MethodInfo readKeyMethod = typeof(Console).GetMethod("ReadKey", new Type[] { });
methIL.Emit(OpCodes.Call, readKeyMethod);
methIL.Emit(OpCodes.Pop); methIL.Emit(OpCodes.Ret); /* 设置assembly入口方法 */
assemblyBuilder.SetEntryPoint(mainMethod, PEFileKinds.ConsoleApplication); SaveAssembly();
Console.WriteLine("生成成功");
Console.ReadKey();
} static void InitAssembly()
{
AssemblyName assemblyName = new AssemblyName(namespaceName);
assemblyBuilder = AppDomain.CurrentDomain.DefineDynamicAssembly(assemblyName, AssemblyBuilderAccess.RunAndSave);
moduleBuilder = assemblyBuilder.DefineDynamicModule(assemblyName.Name, binaryName);
} static void SaveAssembly()
{
Type t = typeBuilder.CreateType(); //完成Type，这是必须的
assemblyBuilder.Save(binaryName);
}
}
}
调用 HelloWorldILGenerator.Generate()后生成ILHelloWorldDemo.exe文件，打开它运行的效果和C#版的"hello world"的是一样的，
用ILSpy对ILHelloWorldDemo.exe进行反编译，反编译的源码也和和C#版的"hello world"的是一样的。