publicclassPeople { publicstring Name { get; set; } }
然后通过直接代码调用方式来取1千万次看要花多少时间:
privatestaticvoidDirectly() { People people = new People { Name = "Wayne" }; Stopwatch stopwatch = Stopwatch.StartNew(); for (int i = 0; i < 10000000; i++) { objectvalue = people.Name; } stopwatch.Stop(); Console.WriteLine("Directly: {0}ms", stopwatch.ElapsedMilliseconds); }
privatestaticvoidReflection() { People people = new People { Name = "Wayne" }; Type type = typeof(People); PropertyInfo property = type.GetProperty("Name"); Stopwatch stopwatch = Stopwatch.StartNew(); for (int i = 0; i < 10000000; i++) { objectvalue = property.GetValue(people); } stopwatch.Stop(); Console.WriteLine("Reflection: {0}ms", stopwatch.ElapsedMilliseconds); }
privatestaticvoidLambda() { People people = new People { Name = "Wayne" }; Type type = typeof(People); var parameter = Expression.Parameter(type, "m");//参数m PropertyInfo property = type.GetProperty("Name"); Expression expProperty = Expression.Property(parameter, property.Name);//取参数的属性m.Name var propertyDelegateExpression = Expression.Lambda(expProperty, parameter);//变成表达式 m => m.Name var propertyDelegate = (Funcobject>)propertyDelegateExpression.Compile();//编译成委托 Stopwatch stopwatch = Stopwatch.StartNew(); for (int i = 0; i < 10000000; i++) { objectvalue = propertyDelegate.Invoke(people); } stopwatch.Stop(); Console.WriteLine("Lambda:{0}ms", stopwatch.ElapsedMilliseconds); }
delegateobjectMemberGetDelegate(People p); privatestaticvoidDelegate() { People people = new People { Name = "Wayne" }; Type type = typeof(People); PropertyInfo property = type.GetProperty("Name"); MemberGetDelegate memberGet = (MemberGetDelegate)System.Delegate.CreateDelegate(typeof(MemberGetDelegate), property.GetGetMethod()); Stopwatch stopwatch = Stopwatch.StartNew(); for (int i = 0; i < 10000000; i++) { objectvalue = memberGet(people); } stopwatch.Stop(); Console.WriteLine("Delegate: {0}ms", stopwatch.ElapsedMilliseconds); }
然后我们测试一下,大概花了38ms,性能几乎与直接调用一致:
最后做一个简单的封装,缓存一下创建的Delegate
publicclass PropertyValue { privatestatic ConcurrentDictionary<string, MemberGetDelegate> _memberGetDelegate = new ConcurrentDictionary<string, MemberGetDelegate>(); delegate object MemberGetDelegate(T obj); publicPropertyValue(T obj) { Target = obj; } public T Target { get; privateset; } public object Get(string name) { MemberGetDelegate memberGet = _memberGetDelegate.GetOrAdd(name, BuildDelegate); return memberGet(Target); } private MemberGetDelegate BuildDelegate(string name) { Type type = typeof(T); PropertyInfo property = type.GetProperty(name); return (MemberGetDelegate)Delegate.CreateDelegate(typeof(MemberGetDelegate), property.GetGetMethod()); } }
这样使用起来就方便多了
People people = new People { Name = "Wayne" }; PropertyValue propertyValue = new PropertyValue(people); objectvalue = propertyValue.Get("Name");