81 lines
1.9 KiB
Dart
81 lines
1.9 KiB
Dart
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/**
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工厂模式(Factory Pattern)
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意图：定义一个创建对象的接口，让其子类自己决定实例化哪一个工厂类，工厂模式使其创建过程延迟到子类进行。
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主要解决：主要解决接口选择的问题。
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何时使用：我们明确地计划不同条件下创建不同实例时。
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如何解决：让其子类实现工厂接口，返回的也是一个抽象的产品。
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*/
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main(List<String> args) {
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var shapeFactory = ShapeFactory();
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//获取 Circle 的对象，并调用它的 draw 方法
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Shape shape1 = shapeFactory.getShape("CIRCLE");
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//调用 Circle 的 draw 方法
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shape1.draw();
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//获取 Rectangle 的对象，并调用它的 draw 方法
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Shape shape2 = shapeFactory.getShape("RECTANGLE");
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//调用 Rectangle 的 draw 方法
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shape2.draw();
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//获取 Square 的对象，并调用它的 draw 方法
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Shape shape3 = shapeFactory.getShape("SQUARE");
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//调用 Square 的 draw 方法
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shape3.draw();
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}
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//////////////////////////////////////////////////////////////////
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///
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/// 创建一个接口
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///
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abstract class Shape {
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void draw();
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}
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///
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/// 创建实现接口的实体类
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///
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class Rectangle implements Shape {
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@override
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void draw() {
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print("Inside Rectangle::draw() method.");
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}
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}
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class Square implements Shape {
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@override
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void draw() {
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print("Inside Square::draw() method.");
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}
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}
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class Circle implements Shape {
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@override
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void draw() {
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print("Inside Circle::draw() method.");
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}
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}
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///
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/// 创建一个工厂
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///
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class ShapeFactory {
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//使用 getShape 方法获取形状类型的对象
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Shape getShape(String shapeType) {
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switch (shapeType?.toUpperCase()) {
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case "CIRCLE":
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return Circle();
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break;
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case "RECTANGLE":
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return Rectangle();
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break;
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case "SQUARE":
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return Square();
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break;
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default:
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return null;
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}
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}
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}
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