Factory Pattern using java for input parameter class

I have Method which return respected Factory base on behavior it should return respected Factory object. How should I implement this using java?

public Object getCurre开发者_StackOverflow社区ntBehaviour(Class behavior) {

    //e.g behavior type is entity it should return entity factory

    //if behavior type is VO it should return VO factory

}


class EntiryFactory{
}

class VoFactory{
}

I would suggest you create 2 bases classes, 1 for entity, 1 for VO.

Example:

public abstract class Entity implements Serializable {

}

public abstract class AbstractVO {


}

Then, use a Abstract Factory pattern for each object's Factory

public AbstractFactory {

    private AbstractFactory() {}

    public abstract Factory getFactory(Class clazz) {
        if (Entity.class.isAssignableFrom(clazz)) {
            return new EntityFactory();
        }

        if (AbstractVO.class.isAssignableFrom(clazz)) {
            return new VOFactory();
        }

        return null;
    }
}

I am using a Class.isAssignableFrom() method to say that subclassed classes is assignable from the parent class (which it does, if you understand what I'm trying to say). That's the trick here.

For this, I would make a Factory for each object

public abstract Factory<T> {

    public abstract T createObject();
}

public class EntityFactory extends Factory<Entity> {

    public Entity createObject(Class entityClass) {
        try {
            return entityClass.newInstance();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

public class VOFactory extends Factory<AbstractVO> {

    public AbstractVO createObject(Class voClass) {
        try {
            return voClass.newInstance();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

Finally, getting the object

Entity entity = (Entity)AbstractFactory.getFactory(Entity.class).createObject();

If I understood your question correctly, I believe you are essentially asking how to return the appropriate instance from getCurrentBehaviour(Class behaviour)

Since the argument is a Class object, you can use Class.isAssignableFrom(Class c) to check if the class or interface represented by this Class object is either the same as, or is a superclass or superinterface of, the class or interface represented by the specified Class parameter.

Here goes:

public Object getCurrentBehaviour(Class behavior) {

    if(behavior.isAssignableFrom(EntiryFactory.class) {
        // create an instance of EntiryFactory
    }

    else if(behavior.isAssignableFrom(VoFactory.class) {
        // create an instance of VoFactory
    }

    return created_instance;
}