总结用表达式数调用的实例代码-C#.Net教程-PHP中文网

总结用表达式数调用的实例代码

零下一度

发布： 2017-06-23 16:17:24

原创

1707人浏览过

照着利用表达式树构建委托改善反射性能做了一点小更改正好适合自己用

    public static class DynamicMethodBuilder
    {public static Delegate BuildDynamicDelegate(MethodInfo methodInfo, ConstructorInfo constructorInfo = null)
        {if (methodInfo == null)throw new ArgumentNullException("methodInfo");
            List<ParameterExpression> paramExpressions = methodInfo.GetParameters().Select((p, i) =>{var name = "param" + (i + 1);return Expression.Parameter(p.ParameterType, name);
            }).ToList();
            MethodCallExpression callExpression;if (methodInfo.IsStatic)
            {//Call(params....)callExpression = Expression.Call(methodInfo, paramExpressions);
            }else{if (constructorInfo != null)
                {//Instance(params).Call(params....)List<ParameterExpression> constructorParamExpressions = constructorInfo.GetParameters().Select((p, i) =>{var name = "constparam" + (i + 1);return Expression.Parameter(p.ParameterType, name);
                    }).ToList();
                    callExpression = Expression.Call(Expression.New(constructorInfo, constructorParamExpressions), methodInfo, paramExpressions);
                    paramExpressions.InsertRange(0, constructorParamExpressions);
                }else{
                    callExpression = Expression.Call(Expression.New(methodInfo.ReflectedType), methodInfo, paramExpressions);
                }
            }return Expression.Lambda(callExpression, paramExpressions).Compile();
        } 
    }

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测试：

    public class Baby
    {
        private readonly DateTime _birthDay;
        public Baby(DateTime birthDay)
        {
            _birthDay = birthDay;
        }
        public Baby()
        {
            _birthDay = DateTime.Now;
        }

        public string GetBabyInfo(string name, int sex) => $"姓名：{name} , 出生天数：{ DateTime.Now- _birthDay} ,性别 ：{(sex == 1 ? "男" : "女")}";

    }

    class Program
    {
        static void Main(string[] args)
        {
            Type targetType = Assembly.GetExecutingAssembly().GetType("ConsoleApplication1.Baby");

            MethodInfo methodInfo = targetType.GetMethod("GetBabyInfo", new[] { typeof(string), typeof(int) });
            ConstructorInfo constructor = targetType.GetConstructor(new[] { typeof(DateTime) });

            WithConstructor(methodInfo, constructor);
            WithOutConstructor(methodInfo);
            Console.ReadKey();
        }
        static void WithConstructor(MethodInfo methodInfo, ConstructorInfo constructor)
        {
            var func = (Func<DateTime, string, int, string>)DynamicMethodBuilder.BuildDynamicDelegate(methodInfo, constructor);
            Console.WriteLine(func(DateTime.Now.AddDays(-100), "糖墩儿", 1));
        }
        static void WithOutConstructor(MethodInfo methodInfo)
        {
            var func = (Func<string, int, string>)DynamicMethodBuilder.BuildDynamicDelegate(methodInfo);
            Console.WriteLine(func("糖墩儿", 1));
        }
    }

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