对象创建方式

原创已于 2022-09-10 18:09:33 修改 · 101 阅读

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#java #开发语言

于 2022-08-16 18:03:16 首次发布

本文探讨了两种在Java中优化对象创建的方法：使用空白枚举结合集合，以及结合Supplier的枚举。通过枚举类型 WeaponType，展示了如何静态初始化Weapon对象并实现工厂方法。同时，引入反射技术，展示了如何根据类名动态创建对象，并通过参数传递实现更灵活的实例化。这些技术在减少代码冗余和提高代码灵活性方面具有重要意义。

空白枚举+集合

public enum WeaponType {
    SWEAR
}

public class WeaponFactory {

    private static final HashMap<WeaponType, Weapon> hashMap = new HashMap<>() {
        {
            put(WeaponType.SWEAR, new Swear());
        }
    };
    
    public static Weapon newInstance(WeaponType weaponType) {
        return hashMap.get(WeaponType.SWEAR);
    }
}

枚举+Supplier

@Getter
@RequiredArgsConstructor
public enum WeaponType {
    SWEAR(Swear::new);

    private final Supplier<Weapon> weaponConstructor;
}

public class WeaponFactory {
    
    public static Weapon newInstance(WeaponType weaponType) {
        return weaponType.getWeaponConstructor().get();
    }
}

反射

public class WeaponFactory {

    public static Weapon newInstance(Class<? extends Weapon> weaponClass, Object... args) {
        Class<?>[] parameters = (Class<?>[]) Arrays.stream(args).map(Object::getClass).toArray();
        try {
            return weaponClass.getConstructor(parameters).newInstance();
        } catch (NoSuchMethodException | InstantiationException | IllegalAccessException | InvocationTargetException e) {
            throw new RuntimeException(e);
        }
    }
}

反射+枚举

@Getter
@RequiredArgsConstructor
public enum WeaponType {
    SWEAR(Swear.class);

    private final Class<? extends Weapon> weaponClass;
}

public class WeaponFactory {
    public static Weapon newInstance(WeaponType weaponType, Object... args) {
        Class<? extends Weapon> weaponClass = weaponType.getWeaponClass();
        Class<?>[] parameters = (Class<?>[]) Arrays.stream(args).map(Object::getClass).toArray();
        try {
            return weaponClass.getConstructor(parameters).newInstance();
        } catch (NoSuchMethodException | InstantiationException | IllegalAccessException | InvocationTargetException e) {
            throw new RuntimeException(e);
        }
    }
}