如何實(shí)現(xiàn)直接調(diào)用vs反射調(diào)用的實(shí)例教程

 1 namespace ConsoleApplication7 2 { 3     class Program 4     { 5         static void Main(string[] args) 6         { 7             //比較直接調(diào)用和反射調(diào)用的性能差異 8             //7ms vs 365ms 9             int times = 1000000;10             var program = new Program();11             CodeTimerHelper.Initialize();12 13             CodeTimerHelper.Time("直接調(diào)用", times, () =>14             {15                 program.Call();16             });17 18             var t = typeof(Program);19             var obj = Activator.CreateInstance(t);20             CodeTimerHelper.Time("反射調(diào)用", times, () =>21             {22                 t.InvokeMember("Call", BindingFlags.InvokeMethod, null, obj, null);23             });24 25             Console.ReadKey();26         }27 28         /// <summary>29         /// 測試方法30         /// </summary>31         public void Call()32         {33         }34 35     }36 }

1 //3，基于表達(dá)式樹2 var methodInfo = t.GetMethod("Call");3 var executor = new DynamicMethodExecutor(methodInfo);4 CodeTimerHelper.Time("Dynamic executor", times, () =>5 {6     executor.Execute(obj, null);7 });

 1 /// <summary> 2 ///  3 /// </summary> 4 public class DynamicMethodExecutor 5 { 6     private Func<object, object[], object> m_execute; 7  8     public DynamicMethodExecutor(MethodInfo methodInfo) 9     {10         this.m_execute = this.GetExecuteDelegate(methodInfo);11     }12 13     public object Execute(object instance, object[] parameters)14     {15         return this.m_execute(instance, parameters);16     }17 18     private Func<object, object[], object> GetExecuteDelegate(MethodInfo methodInfo)19     {20         // parameters to execute21         ParameterExpression instanceParameter = Expression.Parameter(typeof(object), "instance");22         ParameterExpression parametersParameter = Expression.Parameter(typeof(object[]), "parameters");23 24         // build parameter list25         List<Expression> parameterExpressions = new List<Expression>();26         ParameterInfo[] paramInfos = methodInfo.GetParameters();27         for (int i = 0; i < paramInfos.Length; i++)28         {29             // (Ti)parameters[i]30             BinaryExpression valueObj = Expression.ArrayIndex(parametersParameter, Expression.Constant(i));31             UnaryExpression valueCast = Expression.Convert(valueObj, paramInfos[i].ParameterType);32             parameterExpressions.Add(valueCast);33         }34 35         // non-instance for static method, or ((TInstance)instance)36         Expression instanceCast = methodInfo.IsStatic ? null : Expression.Convert(instanceParameter, methodInfo.ReflectedType);37 38         // static invoke or ((TInstance)instance).Method39         MethodCallExpression methodCall = Expression.Call(instanceCast, methodInfo, parameterExpressions);40 41         // ((TInstance)instance).Method((T0)parameters[0], (T1)parameters[1], ...)42         if (methodCall.Type == typeof(void))43         {44             Expression<Action<object, object[]>> lambda = Expression.Lambda<Action<object, object[]>>(methodCall, instanceParameter, parametersParameter);45             Action<object, object[]> execute = lambda.Compile();46             return (instance, parameters) =>47             {48                 execute(instance, parameters);49                 return null;50             };51         }52         else53         {54             UnaryExpression castMethodCall = Expression.Convert(methodCall, typeof(object));55             Expression<Func<object, object[], object>> lambda = Expression.Lambda<Func<object, object[], object>>(castMethodCall, instanceParameter, parametersParameter);56             return lambda.Compile();57         }58     }