C#取代反射取值的方法

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public class DynamicMethod<T>
   {
       internal static Func<object, string, object> GetValueDelegate;
       internal static Action<object, string, object> SetValueDelegate;

       public object GetValue(T instance, string memberName)
       {
           return GetValueDelegate(instance, memberName);
       }

       public void SetValue(T instance, string memberName, object newValue)
       {
           SetValueDelegate(instance, memberName, newValue);
       }

       public object GetValue(object instance, string memberName)
       {
           return GetValueDelegate(instance, memberName);
       }

       public void SetValue(object instance, string memberName, object newValue)
       {
           SetValueDelegate(instance, memberName, newValue);
       }

       static DynamicMethod()
       {
           GetValueDelegate = GenerateGetValue();
           SetValueDelegate = GenerateSetValue();
       }

       private static Func<object, string, object> GenerateGetValue()
       {
           var type = typeof(T);
           var instance = Expression.Parameter(typeof(object), "instance");
           var memberName = Expression.Parameter(typeof(string), "memberName");
           var nameHash = Expression.Variable(typeof(int), "nameHash");
           var calHash = Expression.Assign(nameHash, Expression.Call(memberName, typeof(object).GetMethod("GetHashCode")));
           var cases = new List<SwitchCase>();
           foreach (var propertyInfo in type.GetProperties())
           {
               var property = Expression.Property(Expression.Convert(instance, typeof(T)), propertyInfo.Name);
               var propertyHash = Expression.Constant(propertyInfo.Name.GetHashCode(), typeof(int));

               cases.Add(Expression.SwitchCase(Expression.Convert(property, typeof(object)), propertyHash));
           }
           var switchEx = Expression.Switch(nameHash, Expression.Constant(null), cases.ToArray());
           var methodBody = Expression.Block(typeof(object), new[] { nameHash }, calHash, switchEx);

           return Expression.Lambda<Func<object, string, object>>(methodBody, instance, memberName).Compile();
       }

       private static Action<object, string, object> GenerateSetValue()
       {
           var type = typeof(T);
           var instance = Expression.Parameter(typeof(object), "instance");
           var memberName = Expression.Parameter(typeof(string), "memberName");
           var newValue = Expression.Parameter(typeof(object), "newValue");
           var nameHash = Expression.Variable(typeof(int), "nameHash");
           var calHash = Expression.Assign(nameHash, Expression.Call(memberName, typeof(object).GetMethod("GetHashCode")));
           var cases = new List<SwitchCase>();
           foreach (var propertyInfo in type.GetProperties())
           {
               if (propertyInfo.CanWrite)
               {
                   var property = Expression.Property(Expression.Convert(instance, typeof(T)), propertyInfo.Name);
                   var setValue = Expression.Assign(property, Expression.Convert(newValue, propertyInfo.PropertyType));
                   var propertyHash = Expression.Constant(propertyInfo.Name.GetHashCode(), typeof(int));

                   cases.Add(Expression.SwitchCase(Expression.Convert(setValue, typeof(object)), propertyHash));
               }
           }
           var switchEx = Expression.Switch(nameHash, Expression.Constant(null), cases.ToArray());
           var methodBody = Expression.Block(typeof(object), new[] { nameHash }, calHash, switchEx);

           return Expression.Lambda<Action<object, string, object>>(methodBody, instance, memberName, newValue).Compile();
       }

}

嗯，记录一下，这个方法可以对实体取代反射取值赋值，不记得哪找到的了

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