設計模式之工廠

簡單工廠模式：由一個工廠對象決定創建出哪一種類的實例。

1.抽象類

public abstract class People {
    public  abstract void doSth();
}

2.具體類

public class Man extends People{
    @Override
    public void doSth() {
        System.out.println("I'm a man,I'm coding.");
    }
}

3.具體類

public class Girl extends People{

    @Override
    public void doSth() {
        System.out.println("I'm a girl,I'm eating.");
    }
}

4.工廠

public class PeopleFactory {

    public static People getSpecificPeople(String type){
        if("A-Man".equals(type)){
            return new Man();
        }else if("B-Girl".equals(type)){
            return new Girl();
        }else {
            return null;
        }
    }
}

5.測試代碼

public class PeopleTestDemo {
    public static void main(String[] args) {
        People man = PeopleFactory.getSpecificPeople("A-Man");
        Objects.requireNonNull(man,"對象不存在.");
        man.doSth();

        People girl = PeopleFactory.getSpecificPeople("B-Girl");
        Objects.requireNonNull(girl,"對象不存在");
        girl.doSth();

        People foodie = PeopleFactory.getSpecificPeople("Foodie");
        Objects.requireNonNull(foodie,"對象不存在");
        foodie.doSth();
    }
}

工廠方法模式：定義一個用於創建對象的介面，讓子類去決定實例化哪一個類。工廠方法使一個類的實例化延遲到其子類。

1.抽象工廠

public interface PeopleFactory{
    public  People createPeople();
}

2.抽象產品和具體實現類。

public  abstract class People{
    public abstract void doSth();
}

public class Man extends People {
    @Override
    public void doSth() {
        System.out.println("I'm a man,I'm coding.");
    }
}

public class Girl extends People {

    @Override
    public void doSth() {
        System.out.println("I'm a girl,I'm eating.");
    }
}

3.具體工廠，用來具體實現哪個產品。

public class ManFactory implements PeopleFactory{
    @Override
    public People createPeople() {
        return new Man();
    }
}

public class GirlFactory implements PeopleFactory{
    @Override
    public People createPeople() {
        return new Girl();
    }
}