[英]Java dealing with a lot of concrete factories
I want to generalize a repetitive piece of Java code for a lot of (~40-50) similar entities (in my case, this piece is indexing of files with these entities). 我想为很多(〜40-50)个相似的实体概括一个重复的Java代码(在我的情况下,这是用这些实体对文件进行索引)。
I tried to refactor it with generic method, but, as a result, I get a constructor of generic class that is apparently prohibited in Java. 我试图使用泛型方法对其进行重构,但是结果,我得到了Java中显然禁止的泛型类的构造函数。 To avoid this, I implemented abstract factory pattern and here's what I've get.
为避免这种情况,我实现了抽象工厂模式,这就是我所得到的。
public <E extends CMObject, F extends IndexedFile<E>> F indexFile(CMFactory<E, F> factory) {
F items;
ByteBuffer[] buffs;
// ...filling buffers...
items = factory.makeFile(buffs); // as I cannot do items = new F(buffs)
return items;
}
public CityFile getCities() {
return indexFile(new CityFactory());
}
public ContinentFile getContinents() {
return indexFile(new ContinentFactory());
}
// a lot of more
This solves an issue of creating an instance of generic class. 这解决了创建通用类实例的问题。 However, I now face a task of creating a concrete factory for each single entity that seems to be a lot of monotonous work as they all look like each other.
但是,我现在面临着为每个实体创建一个具体工厂的任务,这似乎是很多单调的工作,因为它们看上去彼此相似。
public abstract class CMFactory<E extends CMObject, F extends IndexedFile<E>> {
public abstract F makeFile(ByteBuffer[] buff);
}
public class CityFactory extends CMFactory<City, CityFile> {
@Override
public CityFile makeFile(ByteBuffer[] buff) {
return new CityFile(buff);
}
}
public class ContinentFactory extends CMFactory<Continent, ContinentFile> {
@Override
public ContinentFile makeFile(ByteBuffer[] buffs) {
return new ContinentFile(buffs);
}
}
The question is: is there any way to automatize creation of such factories? 问题是:是否有任何方法可以自动创建此类工厂? Or maybe is there another pattern that can at least make such creation less painful?
也许还有另一种模式至少可以减轻这种创作的痛苦?
I tried to use IntelliJ IDEA's Replace Constructor with Factory Method refactor, but it didn't help me. 我试图将IntelliJ IDEA的Replace Constructor与Factory Method重构一起使用,但是它没有帮助。
Since your CMFactory
is almost a functional interface you can use constructor handles instead of implementing CMFactory
for each concrete class: 由于
CMFactory
几乎是一个功能接口,因此可以使用构造函数句柄,而不是为每个具体类实现CMFactory
:
Make CMFactory
an interface: 使
CMFactory
接口:
public interface CMFactory<E extends CMObject, F extends IndexedFile<E>> {
public abstract F makeFile(ByteBuffer[] buff);
}
and then write 然后写
public CityFile getCities() {
return indexFile(CityFile::new);
}
You can even discard CMFactory
and use java.util.Function
: 您甚至可以丢弃
CMFactory
并使用java.util.Function
:
public <E extends CMObject, F extends IndexedFile<E>> F indexFile(Function<ByteBuffer[],F> factory) {
ByteBuffer[] buffs;
// ...filling buffers...
return factory.apply(buffs);
}
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