java 抽象工厂模式 例子

抽象工厂模式是一种创建型设计模式，它提供了一种创建一系列相关或相互依赖对象的接口，而无需指定它们具体的类。下面是一个 Java 抽象工厂模式的例子：

public interface AbstractFactory {
    public Shape getShape(String shapeType);
}

public class ShapeFactory implements AbstractFactory {
    @Override
    public Shape getShape(String shapeType) {
        if (shapeType == null) {
            return null;
        }
        if (shapeType.equalsIgnoreCase("CIRCLE")) {
            return new Circle();
        } else if (shapeType.equalsIgnoreCase("RECTANGLE")) {
            return new Rectangle();
        } else if (shapeType.equalsIgnoreCase("SQUARE")) {
            return new Square();
        }
        return null;
    }
}

public interface Shape {
    void draw();
}

public class Circle implements Shape {
    @Override
    public void draw() {
        System.out.println("Inside Circle::draw() method.");
    }
}

public class Rectangle implements Shape {
    @Override
    public void draw() {
        System.out.println("Inside Rectangle::draw() method.");
    }
}

public class Square implements Shape {
    @Override
    public void draw() {
        System.out.println("Inside Square::draw() method.");
    }
}

public class FactoryProducer {
    public static AbstractFactory getFactory(boolean rounded) {
        if (rounded) {
            return new RoundedShapeFactory();
        } else {
            return new ShapeFactory();
        }
    }
}

public class RoundedShapeFactory implements AbstractFactory {
    @Override
    public Shape getShape(String shapeType) {
        if (shapeType == null) {
            return null;
        }
        if (shapeType.equalsIgnoreCase("CIRCLE")) {
            return new RoundedCircle();
        } else if (shapeType.equalsIgnoreCase("RECTANGLE")) {
            return new RoundedRectangle();
        } else if (shapeType.equalsIgnoreCase("SQUARE")) {
            return new RoundedSquare();
        }
        return null;
    }
}

public class RoundedCircle implements Shape {
    @Override
    public void draw() {
        System.out.println("Inside RoundedCircle::draw() method.");
    }
}

public class RoundedRectangle implements Shape {
    @Override
    public void draw() {
        System.out.println("Inside RoundedRectangle::draw() method.");
    }
}

public class RoundedSquare implements Shape {
    @Override
    public void draw() {
        System.out.println("Inside RoundedSquare::draw() method.");
    }
}

在这个例子中，我们定义了一个 `AbstractFactory` 接口和两个实现类 `ShapeFactory` 和 `RoundedShapeFactory`。`ShapeFactory` 用于创建普通形状，而 `RoundedShapeFactory` 用于创建圆角形状。我们还定义了一个 `Shape` 接口和三个实现类 `Circle`、`Rectangle` 和 `Square`，它们分别表示圆形、矩形和正方形。在 `ShapeFactory` 和 `RoundedShapeFactory` 中，我们实现了 `AbstractFactory` 接口中的 `getShape()` 方法，用于创建具体的形状对象。最后，我们定义了一个 `FactoryProducer` 工厂类，用于根据需要返回不同的工厂对象。