使用cecil 完毕 code injection

1. 安装Mono.Cecil

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2. 创建一个測试项目:

加入測试方法：

这种方法的返回值会被动态重写.

 public class Class1
    {
       public static string Test()
       {
           return "ok";
       }
    }

3. code Injection 代码：

var path = @"\XX\bin\Debug\ClassLibrary1.dll";

           var assembly = AssemblyDefinition.ReadAssembly
                (path);
           var type =assembly.MainModule.GetType("ClassLibrary1.Class1");
           var foundMethod = type.GetMethods().First(m => m.Name =="Test");
////清空当前方法指令
           foundMethod.Body.Instructions.Clear();
////获得当前IL的指令执行器
           var worker = foundMethod.Body.GetILProcessor();
////改动返回值
           Instruction ins1 = worker.Create(OpCodes.Ldstr, "will be changed onnext time run");
           Instruction ins2 = worker.Create(OpCodes.Ret);

           worker.Append(ins1);
           worker.Append(ins2);
////保存DLL文件
           assembly.Write(path);

////下次调用就会看到（由于新保存的DLL下次才干载入到）
           Console.WriteLine(Class1.Test());
           Console.Read();

4. 执行查看结果

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