本文小编为大家详细介绍“在.NET平台怎么使用ReflectionDynamicObject优化反射”，内容详细，步骤清晰，细节处理妥当，希望这篇“在.NET平台怎么使用ReflectionDynamicObject优化反射”文章能帮助大家解决疑惑，下面跟着小编的思路慢慢深入，一起来学习新知识吧。
基于封装的原则，API 的设计者会将部分成员（属性、字段、方法等）隐藏以保证健壮性。但总有需要直接访问这些私有成员的情况。
为了访问一个类型的私有成员，除了更改 API 设计还有就是使用反射技术：
public class MyApi{public MyApi(){_createdAt = DateTime.Now;}private DateTime _createdAt;public int ShowTimes { get; private set; }public void ShowCreateTime(){Console.WriteLine(_createdAt);ShowTimes++;}}void Main(){var api = new MyApi();var field = api.GetType().GetField("_createdAt", BindingFlags.NonPublic | BindingFlags.Instance);var value = field.GetValue(api);Console.WriteLine(value);}这种写法并不优雅：
代码冗长，编写麻烦。实现比较绕，不太直观。
笔者基于“动态类型技术”探索出了一种相对来说比较优雅的方案用于美化上述代码，并为其命名为 ReflectionDynamicObject ：
void Main(){ var api = new MyApi(); dynamic wrapper = ReflectionDynamicObject.Wrap(api); Console.WriteLine(wrapper._createdAt);}除了支持获取值，ReflectionDynamicObject 还支持赋值：
void Main(){ var api = new MyApi(); dynamic wrapper = ReflectionDynamicObject.Wrap(api); wrapper._createdAt = new DateTime(2022, 2, 2, 22, 22, 22); api.ShowCreateTime();}除了字段，当然也支持对属性的操作：
void Main(){ var api = new MyApi(); dynamic wrapper = ReflectionDynamicObject.Wrap(api); wrapper.ShowTimes = 100; Console.WriteLine(wraper.ShowTimes);}在对属性的支持上，ReflectionDynamicObject 使用了“快速反射”技术，将取值和复制操作生成了委托以优化性能。
ReflectionDynamicObject 的实现原理
ReflectionDynamicObject 派生自 DynamicObject ，其内部通过反射技术获取到所有的属性和字段并对其 getter 和 setter 方法进行存储并通过 TryGetMember 和 TrySetMember 方法经运行时调用。
ReflectionDynamicObject 的源代码
public sealed class ReflectionDynamicObject : DynamicObject{ private readonly object _instance; private readonly Accessor _accessor; private ReflectionDynamicObject(object instance) { _instance = instance ?? throw new ArgumentNullException(nameof(instance)); _accessor = GetAccessor(instance.GetType()); } public static ReflectionDynamicObject Wrap(Object value) if (value == null) throw new ArgumentNullException(nameof(value)); return new ReflectionDynamicObject(value); public override bool TryGetMember(GetMemberBinder binder, out object result) if (_accessor.TryFindGetter(binder.Name, out var getter)) { result = getter.Get(_instance); return true; } return base.TryGetMember(binder, out result); public override bool TrySetMember(SetMemberBinder binder, object value) if (_accessor.TryFindSetter(binder.Name, out var setter)) setter.Set(_instance, value); return base.TrySetMember(binder, value); #region 快速反射 private interface IGetter object Get(object instance); private interface ISetter void Set(object instance, object value); private class Getter : IGetter private FieldInfo _field; public Getter(FieldInfo field) _field = field ?? throw new ArgumentNullException(nameof(field)); public object Get(object instance) return _field.GetValue(instance); private class Setter : ISetter public Setter(FieldInfo field) public void Set(object instance, object value) _field.SetValue(instance, value); private class Getter<T1, T2> : IGetter private readonly Func<T1, T2> _getter; public Getter(Func<T1, T2> getter) _getter = getter ?? throw new ArgumentNullException(nameof(getter)); return _getter((T1)instance); private class Setter<T1, T2> : ISetter private readonly Action<T1, T2> _setter; public Setter(Action<T1, T2> setter) this._setter = setter ?? throw new ArgumentNullException(nameof(setter)); this._setter.Invoke((T1)instance, (T2)value); private class Accessor public Accessor(Type type) this._type = type ?? throw new ArgumentNullException(nameof(_type)); var getter = new SortedDictionary<string, IGetter>(); var setter = new SortedDictionary<string, ISetter>(); var fields = _type.GetFields(BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic); foreach (var field in fields) { getter[field.Name] = new Getter(field); setter[field.Name] = new Setter(field); } var props = _type.GetProperties(BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic); foreach (var item in props) if (item.CanRead) { var method = item.GetMethod; var funcType = typeof(Func<,>).MakeGenericType(item.DeclaringType, item.PropertyType); var func = method.CreateDelegate(funcType); var getterType = typeof(Getter<,>).MakeGenericType(item.DeclaringType, item.PropertyType); var get = (IGetter)Activator.CreateInstance(getterType, func); getter[item.Name] = get; } if (item.CanWrite) var method = item.SetMethod; var actType = typeof(Action<,>).MakeGenericType(item.DeclaringType, item.PropertyType); var act = method.CreateDelegate(actType); var setterType = typeof(Setter<,>).MakeGenericType(item.DeclaringType, item.PropertyType); var set = (ISetter)Activator.CreateInstance(setterType, act); setter[item.Name] = set; _getters = getter; _setters = setter; private readonly Type _type; private readonly IReadOnlyDictionary<string, IGetter> _getters; private readonly IReadOnlyDictionary<string, ISetter> _setters; public bool TryFindGetter(string name, out IGetter getter) => _getters.TryGetValue(name, out getter); public bool TryFindSetter(string name, out ISetter setter) => _setters.TryGetValue(name, out setter); private static Dictionary<Type, Accessor> _accessors = new Dictionary<Type, Accessor>(); private static object _accessorsLock = new object(); private static Accessor GetAccessor(Type type) if (_accessors.TryGetValue(type, out var accessor)) return accessor; lock (_accessorsLock) if (_accessors.TryGetValue(type, out accessor)) return accessor; accessor = new Accessor(type); var temp = new Dictionary<Type, Accessor>(_accessors); temp[type] = new Accessor(type); _accessors = temp; return accessor; #endregion}ReflectionDynamicObject 的局限性
基于复杂度的考虑，ReflectionDynamicObject 并未添加对“方法”的支持。这也就意味着对方法的调用是缺失的。虽然动态行为让程序摆脱了对字符串的依赖，但是该实现对“重构”的支持仍然不友好。
哪里用到了 ReflectionDynamicObject ？
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