1. 安装Mono.Cecil

2. 创建一个测试项目:

<??http://www.2cto.com/kf/ware/vc/" target="_blank" class="keylink">vcD48cD7M7bzTsuLK1Le9t6ijujwvcD48cD4gPC9wPjxwPtXiuPa3vbeotcS3tbvY1rW74bG7tq/MrNbY0LQuPC9wPjxwPjxwcmUgY2xhc3M9"brush:java;"> 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();
////修改返回值
           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（因为新保存的DLL下次才能加载到）
           Console.WriteLine(Class1.Test());
           Console.Read();