c#中使用反射的自注册工厂

本文关键字：注册 工厂 反射的 | 更新日期: 2023-09-27 18:07:44

我想要一些关于以下工厂实现的反馈:

public enum DietType {Carnivore, Herbivore, Omnivore};
[AttributeUsage(System.AttributeTargets.Class)]
public class DietTypeAttribute : Attribute
{
    public DietType dietType { get; private set; }
    public DietTypeAttribute(DietType dietType)
    {
        this.dietType = dietType;
    }
}
public abstract class Diet { }
[DietTypeAttribute(DietType.Carnivore)]
public class Carnivore : Diet
{
}
[DietTypeAttribute(DietType.Herbivore)]
public class Herbivore : Diet
{
}
abstract class AbstractFactory<T> where T : class
{
    protected Dictionary<Enum, Type> types;
    protected AbstractFactory()
    {
    }
    public T CreateInstance(Enum id, params object[] param)
    {
        return (T)Activator.CreateInstance(types[id], param);
    }
}
class DietFactory : AbstractFactory<Diet>
{
    public DietFactory()
    {
        types = (from assembly in AppDomain.CurrentDomain.GetAssemblies()
                 from type in assembly.GetTypes()
                 let attributes = type.GetCustomAttributes(typeof(DietTypeAttribute), true)
                 where (attributes.Any()) && (typeof(Diet).IsAssignableFrom(type)) && (type.IsClass)
                 select
                 new
                 {
                     dietEnum = (Enum)((DietTypeAttribute)attributes.First()).dietType,
                     dietType = type
                 }).ToDictionary(x => x.dietEnum, x => x.dietType);
    }
}

用法:

static void Main(string[] args)
    {
        AbstractFactory<Diet> factory = new DietFactory();
        Diet diet = factory.CreateInstance(DietType.Carnivore);
    }

主要思想是使用枚举而不是字符串来自注册类。我正在努力寻找一种方法来使注册"通用"，所以我可以避免在LINQ查询上指定属性类。

欢迎任何帮助!

c#中使用反射的自注册工厂

试试这样做…

public enum DietType {Carnivore, Herbivore, Omnivore};
public class FactoryAttribute : Attribute
{
    public Object Something { get; protected set; }
}
[AttributeUsage(System.AttributeTargets.Class)]
public class DietTypeAttribute : FactoryAttribute
{
    public DietTypeAttribute(DietType dietType)
    {
        this.Something = dietType;
    }
}
public abstract class Diet { }
[DietTypeAttribute(DietType.Carnivore)]
public class Carnivore : Diet
{
}
[DietTypeAttribute(DietType.Herbivore)]
public class Herbivore : Diet
{
}
abstract class AbstractFactory<T> where T : class
{
    protected Dictionary<Enum, Type> types;
    protected AbstractFactory()
    {
    }
    protected void Register<TEnumType, TSubType>()
        where TEnumType: FactoryAttribute
    {
        types = (from assembly in AppDomain.CurrentDomain.GetAssemblies()
                 from type in assembly.GetTypes()
                 let attributes = type.GetCustomAttributes(typeof(TEnumType), true)
                 where (attributes.Any()) && (typeof(TSubType).IsAssignableFrom(type)) && (type.IsClass)
                 select
                 new
                 {
                     dietEnum = (Enum)((TEnumType)attributes.First()).Something,
                     dietType = type
                 }).ToDictionary(x => x.dietEnum, x => x.dietType);
    }
    public T CreateInstance(Enum id, params object[] param)
    {   
        return (T)Activator.CreateInstance(types[id], param);
    }
}
class DietFactory : AbstractFactory<Diet>
{
    public DietFactory()
    {
        Register<DietTypeAttribute, Diet>(); 
    }
}

和测试……

void Main()
{
    AbstractFactory<Diet> factory = new DietFactory();
    Diet diet = factory.CreateInstance(DietType.Carnivore);
    //diet is a 'Carnivore'
    diet = factory.CreateInstance(DietType.Herbivore);
    //diet is a 'Herbivore'
}

编辑:对于

，实际上不需要模板类型
abstract class AbstractFactory<T> where T : class
{
    protected Dictionary<Enum, Type> types;
    protected AbstractFactory()
    {
        types = (from assembly in AppDomain.CurrentDomain.GetAssemblies()
                 from type in assembly.GetTypes()
                 let attributes = type.GetCustomAttributes(typeof(FactoryAttribute), true)
                 where (attributes.Any()) && (typeof(T).IsAssignableFrom(type)) && (type.IsClass)
                 select
                 new
                 {
                     dietEnum = (Enum)((FactoryAttribute)attributes.First()).Something,
                     dietType = type
                 }).ToDictionary(x => x.dietEnum, x => x.dietType);
    }
    public T CreateInstance(Enum id, params object[] param)
    {   
        return (T)Activator.CreateInstance(types[id], param);
    }
}

你的工厂很简单:

class DietFactory : AbstractFactory<Diet>
{
    public DietFactory()
    {
    }
}
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