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抽象工厂

Java 抽象工厂模式讲解和代码示例

抽象工厂是一种创建型设计模式 它能创建一系列相关的对象 而无需指定其具体类

抽象工厂定义了用于创建不同产品的接口 但将实际的创建工作留给了具体工厂类 每个工厂类型都对应一个特定的产品变体

在创建产品时 客户端代码调用的是工厂对象的构建方法 而不是直接调用构造函数 new操作符 由于一个工厂对应一种产品变体 因此它创建的所有产品都可相互兼容

客户端代码仅通过其抽象接口与工厂和产品进行交互 该接口允许同一客户端代码与不同产品进行交互 你只需创建一个具体工厂类并将其传递给客户端代码即可

如果你不清楚工厂 工厂方法抽象工厂模式之间的区别 请参阅工厂模式比较

复杂度

流行度

使用示例 抽象工厂模式在 Java 代码中很常见 许多框架和程序库会将它作为扩展和自定义其标准组件的一种方式

以下是来自核心 Java 程序库的一些示例

识别方法 我们可以通过方法来识别该模式——其会返回一个工厂对象 接下来 工厂将被用于创建特定的子组件

跨平台 GUI 组件系列及其创建方式

在本例中 按钮和复选框将被作为产品 它们有两个变体 macOS 版和 Windows 版

抽象工厂定义了用于创建按钮和复选框的接口 而两个具体工厂都会返回同一变体的两个产品

客户端代码使用抽象接口与工厂和产品进行交互 同样的代码能与依赖于不同工厂对象类型的多种产品变体进行交互

buttons: 第一个产品层次结构

buttons/Button.java

package refactoring_guru.abstract_factory.example.buttons;

/**
 * Abstract Factory assumes that you have several families of products,
 * structured into separate class hierarchies (Button/Checkbox). All products of
 * the same family have the common interface.
 *
 * This is the common interface for buttons family.
 */
public interface Button {
    void paint();
}

buttons/MacOSButton.java

package refactoring_guru.abstract_factory.example.buttons;

/**
 * All products families have the same varieties (MacOS/Windows).
 *
 * This is a MacOS variant of a button.
 */
public class MacOSButton implements Button {

    @Override
    public void paint() {
        System.out.println("You have created MacOSButton.");
    }
}

buttons/WindowsButton.java

package refactoring_guru.abstract_factory.example.buttons;

/**
 * All products families have the same varieties (MacOS/Windows).
 *
 * This is another variant of a button.
 */
public class WindowsButton implements Button {

    @Override
    public void paint() {
        System.out.println("You have created WindowsButton.");
    }
}

checkboxes: 第二个产品层次结构

checkboxes/Checkbox.java

package refactoring_guru.abstract_factory.example.checkboxes;

/**
 * Checkboxes is the second product family. It has the same variants as buttons.
 */
public interface Checkbox {
    void paint();
}

checkboxes/MacOSCheckbox.java

package refactoring_guru.abstract_factory.example.checkboxes;

/**
 * All products families have the same varieties (MacOS/Windows).
 *
 * This is a variant of a checkbox.
 */
public class MacOSCheckbox implements Checkbox {

    @Override
    public void paint() {
        System.out.println("You have created MacOSCheckbox.");
    }
}

checkboxes/WindowsCheckbox.java

package refactoring_guru.abstract_factory.example.checkboxes;

/**
 * All products families have the same varieties (MacOS/Windows).
 *
 * This is another variant of a checkbox.
 */
public class WindowsCheckbox implements Checkbox {

    @Override
    public void paint() {
        System.out.println("You have created WindowsCheckbox.");
    }
}

factories

factories/GUIFactory.java: 抽象工厂

package refactoring_guru.abstract_factory.example.factories;

import refactoring_guru.abstract_factory.example.buttons.Button;
import refactoring_guru.abstract_factory.example.checkboxes.Checkbox;

/**
 * Abstract factory knows about all (abstract) product types.
 */
public interface GUIFactory {
    Button createButton();
    Checkbox createCheckbox();
}

factories/MacOSFactory.java: 具体工厂 mac­OS

package refactoring_guru.abstract_factory.example.factories;

import refactoring_guru.abstract_factory.example.buttons.Button;
import refactoring_guru.abstract_factory.example.buttons.MacOSButton;
import refactoring_guru.abstract_factory.example.checkboxes.Checkbox;
import refactoring_guru.abstract_factory.example.checkboxes.MacOSCheckbox;

/**
 * Each concrete factory extends basic factory and responsible for creating
 * products of a single variety.
 */
public class MacOSFactory implements GUIFactory {

    @Override
    public Button createButton() {
        return new MacOSButton();
    }

    @Override
    public Checkbox createCheckbox() {
        return new MacOSCheckbox();
    }
}

factories/WindowsFactory.java: 具体工厂 Windows

package refactoring_guru.abstract_factory.example.factories;

import refactoring_guru.abstract_factory.example.buttons.Button;
import refactoring_guru.abstract_factory.example.buttons.WindowsButton;
import refactoring_guru.abstract_factory.example.checkboxes.Checkbox;
import refactoring_guru.abstract_factory.example.checkboxes.WindowsCheckbox;

/**
 * Each concrete factory extends basic factory and responsible for creating
 * products of a single variety.
 */
public class WindowsFactory implements GUIFactory {

    @Override
    public Button createButton() {
        return new WindowsButton();
    }

    @Override
    public Checkbox createCheckbox() {
        return new WindowsCheckbox();
    }
}

app

app/Application.java: 客户端代码

package refactoring_guru.abstract_factory.example.app;

import refactoring_guru.abstract_factory.example.buttons.Button;
import refactoring_guru.abstract_factory.example.checkboxes.Checkbox;
import refactoring_guru.abstract_factory.example.factories.GUIFactory;

/**
 * Factory users don't care which concrete factory they use since they work with
 * factories and products through abstract interfaces.
 */
public class Application {
    private Button button;
    private Checkbox checkbox;

    public Application(GUIFactory factory) {
        button = factory.createButton();
        checkbox = factory.createCheckbox();
    }

    public void paint() {
        button.paint();
        checkbox.paint();
    }
}

Demo.java: 程序配置

package refactoring_guru.abstract_factory.example;

import refactoring_guru.abstract_factory.example.app.Application;
import refactoring_guru.abstract_factory.example.factories.GUIFactory;
import refactoring_guru.abstract_factory.example.factories.MacOSFactory;
import refactoring_guru.abstract_factory.example.factories.WindowsFactory;

/**
 * Demo class. Everything comes together here.
 */
public class Demo {

    /**
     * Application picks the factory type and creates it in run time (usually at
     * initialization stage), depending on the configuration or environment
     * variables.
     */
    private static Application configureApplication() {
        Application app;
        GUIFactory factory;
        String osName = System.getProperty("os.name").toLowerCase();
        if (osName.contains("mac")) {
            factory = new MacOSFactory();
        } else {
            factory = new WindowsFactory();
        }
        app = new Application(factory);
        return app;
    }

    public static void main(String[] args) {
        Application app = configureApplication();
        app.paint();
    }
}

OutputDemo.txt: 执行结果

You create WindowsButton.
You created WindowsCheckbox.

抽象工厂在其他编程语言中的实现

C# 抽象工厂模式讲解和代码示例 C++ 抽象工厂模式讲解和代码示例 Go 抽象工厂模式讲解和代码示例 PHP 抽象工厂模式讲解和代码示例 Python 抽象工厂模式讲解和代码示例 Ruby 抽象工厂模式讲解和代码示例 Rust 抽象工厂模式讲解和代码示例 Swift 抽象工厂模式讲解和代码示例 TypeScript 抽象工厂模式讲解和代码示例