学步园

如果有以下类Processor.cs

  public class Processor
 {
      public int Process(int value)
       {
          return value + 1;
        }
 }

动态调用Processor类里面的Process函数有如下几种

方法一：直接调用
         Processor test = new Processor();
         int i = 100;
         int value =test.Process(i);
         Response.Write(value.ToString());

　　 输出：101

方法二：用反射机制，Type.InvokeMember()调用

            Processor test = new Processor();
            Type t = typeof(Processor);
            int i=100;
            int value = (int)t.InvokeMember("Process", BindingFlags.Instance | BindingFlags.Public | BindingFlags.InvokeMethod, null, test, new object[] { i });
            Response.Write(value.ToString());

　　   输出：101

方法三：通过一个委托Delegate调用
　　　public delegate int ProcessCaller(int value);
            Processor test = new Processor();
            ProcessCaller processCaller = new ProcessCaller(test.Process);
            int i=100;           
            int value = processCaller(i);
            Response.Write(value.ToString());

            输出：101

方法四：也通过反射机制建立委托再动态调用
            Processor test = new Processor();
            Type type = test.GetType();//获取类型
            MethodInfo methodInfo = type.GetMethod("Process");//获取里面的方法
            object[] args = {1};//表明为一个整型参数
            methodInfo.Invoke(test, args);//应用Processor 里面的Process方法

           Type delegateType = CreateCustomDelegate(methodInfo);//CreateCustomDelegate方法为创建自定义委托      
           Delegate p = Delegate.CreateDelegate(delegateType,test, "Process");
            int i=100;
            int value = (int)p.DynamicInvoke(new object[] { i });
            Response.Write(value.ToString());

            输出：101

方法四当中的CreateCustomDelegate通用方法代码如下：
首先引用using System.Reflection.Emit;

private Type CreateCustomDelegate(MethodInfo targetMethod)
    {
        AssemblyName assembly;
        AssemblyBuilder assemblyBuilder;
        ModuleBuilder modbuilder;
        TypeBuilder typeBuilder;
        MethodBuilder methodBuilder;
        assembly = new AssemblyName();
        assembly.Version = new Version(1, 0, 0, 0);
        assembly.Name = "CallbackGen";
        assemblyBuilder = AppDomain.CurrentDomain.DefineDynamicAssembly(assembly, AssemblyBuilderAccess.RunAndSave);
        modbuilder = assemblyBuilder.DefineDynamicModule("CallbackGenModule", "CallbackGen.dll", true);
        // Create a delegate that has the same signature as the method we would like to hook up to
        typeBuilder = modbuilder.DefineType(targetMethod.Name + "Callback", TypeAttributes.Class | TypeAttributes.Public | TypeAttributes.Sealed |
TypeAttributes.AnsiClass | TypeAttributes.AutoClass, typeof(System.MulticastDelegate));
        ConstructorBuilder constructorBuilder = typeBuilder.DefineConstructor(MethodAttributes.RTSpecialName | MethodAttributes.HideBySig |
MethodAttributes.Public, CallingConventions.Standard, new Type[] { typeof(object), typeof(int) });
        constructorBuilder.SetImplementationFlags(MethodImplAttributes.Runtime | MethodImplAttributes.Managed);
        // Grab the parameters of the method
        ParameterInfo[] parameters = targetMethod.GetParameters();
        Type[] paramTypes = new Type[parameters.Length];
        for (int i = 0; i < parameters.Length; i++)
        {
            paramTypes[i] = parameters[i].ParameterType;
        }
        // Define the Invoke method for the delegate
        methodBuilder = typeBuilder.DefineMethod(
            "Invoke",
            MethodAttributes.Public | MethodAttributes.HideBySig | MethodAttributes.NewSlot | MethodAttributes.Virtual,
            CallingConventions.Standard,
            targetMethod.ReturnType,
            null,
            new Type[] { typeof(System.Runtime.CompilerServices.CallConvCdecl) },
            paramTypes,
            null,
            null);
        methodBuilder.SetImplementationFlags(MethodImplAttributes.Runtime | MethodImplAttributes.Managed);
        // bake it!
        Type t = typeBuilder.CreateType();
        return t;
    }