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通过策略模式实现对象创建工厂

article 2024/9/21 12:36:12

案例：通过策略模式实现对象创建工厂

场景描述：

设计步骤：

注：

案例：通过策略模式实现对象创建工厂

场景描述：

假设要设计一个系统，用来创建不同类型的 Shape 对象（如 Circle、Square、Rectangle）。通常会使用工厂模式来封装对象创建的过程。但是，我们尝试用策略模式来实现这个功能，使得对象的创建方式在运行时动态调整。

设计步骤：

定义Shape接口及其实现类：

interface Shape {
    void draw();
}

class Circle implements Shape {
    @Override
    public void draw() {
        System.out.println("Drawing a Circle");
    }
}

class Square implements Shape {
    @Override
    public void draw() {
        System.out.println("Drawing a Square");
    }
}

class Rectangle implements Shape {
    @Override
    public void draw() {
        System.out.println("Drawing a Rectangle");
    }
}

定义创建策略接口及其实现类：

interface ShapeCreationStrategy {
    Shape createShape();
}

class CircleCreationStrategy implements ShapeCreationStrategy {
    @Override
    public Shape createShape() {
        return new Circle();
    }
}

class SquareCreationStrategy implements ShapeCreationStrategy {
    @Override
    public Shape createShape() {
        return new Square();
    }
}

class RectangleCreationStrategy implements ShapeCreationStrategy {
    @Override
    public Shape createShape() {
        return new Rectangle();
    }
}

定义一个上下文类，用来选择和使用不同的策略：

class ShapeFactoryContext {
    private ShapeCreationStrategy strategy;

    public void setStrategy(ShapeCreationStrategy strategy) {
        this.strategy = strategy;
    }

    public Shape createShape() {
        return strategy.createShape();
    }
}

客户端代码：

public class Main {
    public static void main(String[] args) {
        ShapeFactoryContext context = new ShapeFactoryContext();

        // 使用CircleCreationStrategy
        context.setStrategy(new CircleCreationStrategy());
        Shape shape1 = context.createShape();
        shape1.draw(); // 输出: Drawing a Circle

        // 使用SquareCreationStrategy
        context.setStrategy(new SquareCreationStrategy());
        Shape shape2 = context.createShape();
        shape2.draw(); // 输出: Drawing a Square

        // 使用RectangleCreationStrategy
        context.setStrategy(new RectangleCreationStrategy());
        Shape shape3 = context.createShape();
        shape3.draw(); // 输出: Drawing a Rectangle
    }
}