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Accepted
DiMaAgalakov
Asked:2023-06-29 16:44:49 +0000 UTC2023-06-29 16:44:49 +0000 UTC

按类型从类中获取集合

  • 772

有一个带有集合的类：

public class CollectionsStorage
{
   public ObservableCollection<Car> Cars { get; set; } = new();

   public ObservableCollection<Animal> Animals { get; set; } = new();

   // Тип "T" это Animal или Car.
   public IEnumerable<T>? GetObjects<T>()
   {
     // Здесь надо вернуть коллекцию определённого типа.
   }
}
c#

1 个回答

  1. Best Answer

    根据调用该方法的频率，可以缓存其工作结果

    public class CollectionsStorage
{
    private readonly Dictionary<Type , Object> _objects = new Dictionary<Type , Object>();
    
    public ObservableCollection<Car> Cars { get; set; } = new();
    public ObservableCollection<Animal> Animals { get; set; } = new();

    // Тип "T" это Animal или Car.
    public IEnumerable<T>? GetObjects<T>()
    {
        if (_objects.TryGetValue(typeof(T) , out Object obj))
        {
            return (IEnumerable<T>)obj;
        }

        PropertyInfo[] properties = GetType().GetProperties(BindingFlags.Instance | BindingFlags.Public | BindingFlags.GetProperty)
            .Where(prop => prop.PropertyType.IsAssignableTo(typeof(IEnumerable<T>)))
            .ToArray();
            
        if (properties.Length == 0)
        {
            throw new ArgumentException("Type T not found");
        }

        if (properties.Length > 1)
        {
            throw new ArgumentException("Type T more than one");
        }

        object result = properties.First().GetValue(this)!;
        _objects[typeof(T)] = result;
        return (IEnumerable<T>)result;
    }
}
    • 2

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