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PHP 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、 工厂方法和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 PHP 代码中很常见。 许多框架和程序库将它作为扩展和自定义其标准组件的一种方式。
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。
概念示例
本例说明了抽象工厂设计模式的结构并重点回答了下面的问题：
- 它由哪些类组成？
- 这些类扮演了哪些角色？
- 模式中的各元素会以何种方式相互关联？
了解该模式的结构后， 你可以更容易地理解下面的基于实际情况的 PHP 应用案例。
** index.php: 概念示例
<?php
namespace RefactoringGuru\AbstractFactory\Conceptual;
/**
* The Abstract Factory interface declares a set of methods that return
* different abstract products. These products are called a family and are
* related by a high-level theme or concept. Products of one family are usually
* able to collaborate among themselves. A family of products may have several
* variants, but the products of one variant are incompatible with products of
* another.
*/
interface AbstractFactory
{
public function createProductA(): AbstractProductA;
public function createProductB(): AbstractProductB;
}
/**
* Concrete Factories produce a family of products that belong to a single
* variant. The factory guarantees that resulting products are compatible. Note
* that signatures of the Concrete Factory's methods return an abstract product,
* while inside the method a concrete product is instantiated.
*/
class ConcreteFactory1 implements AbstractFactory
{
public function createProductA(): AbstractProductA
{
return new ConcreteProductA1();
}
public function createProductB(): AbstractProductB
{
return new ConcreteProductB1();
}
}
/**
* Each Concrete Factory has a corresponding product variant.
*/
class ConcreteFactory2 implements AbstractFactory
{
public function createProductA(): AbstractProductA
{
return new ConcreteProductA2();
}
public function createProductB(): AbstractProductB
{
return new ConcreteProductB2();
}
}
/**
* Each distinct product of a product family should have a base interface. All
* variants of the product must implement this interface.
*/
interface AbstractProductA
{
public function usefulFunctionA(): string;
}
/**
* Concrete Products are created by corresponding Concrete Factories.
*/
class ConcreteProductA1 implements AbstractProductA
{
public function usefulFunctionA(): string
{
return "The result of the product A1.";
}
}
class ConcreteProductA2 implements AbstractProductA
{
public function usefulFunctionA(): string
{
return "The result of the product A2.";
}
}
/**
* Here's the the base interface of another product. All products can interact
* with each other, but proper interaction is possible only between products of
* the same concrete variant.
*/
interface AbstractProductB
{
/**
* Product B is able to do its own thing...
*/
public function usefulFunctionB(): string;
/**
* ...but it also can collaborate with the ProductA.
*
* The Abstract Factory makes sure that all products it creates are of the
* same variant and thus, compatible.
*/
public function anotherUsefulFunctionB(AbstractProductA $collaborator): string;
}
/**
* Concrete Products are created by corresponding Concrete Factories.
*/
class ConcreteProductB1 implements AbstractProductB
{
public function usefulFunctionB(): string
{
return "The result of the product B1.";
}
/**
* The variant, Product B1, is only able to work correctly with the variant,
* Product A1. Nevertheless, it accepts any instance of AbstractProductA as
* an argument.
*/
public function anotherUsefulFunctionB(AbstractProductA $collaborator): string
{
$result = $collaborator->usefulFunctionA();
return "The result of the B1 collaborating with the ({$result})";
}
}
class ConcreteProductB2 implements AbstractProductB
{
public function usefulFunctionB(): string
{
return "The result of the product B2.";
}
/**
* The variant, Product B2, is only able to work correctly with the variant,
* Product A2. Nevertheless, it accepts any instance of AbstractProductA as
* an argument.
*/
public function anotherUsefulFunctionB(AbstractProductA $collaborator): string
{
$result = $collaborator->usefulFunctionA();
return "The result of the B2 collaborating with the ({$result})";
}
}
/**
* The client code works with factories and products only through abstract
* types: AbstractFactory and AbstractProduct. This lets you pass any factory or
* product subclass to the client code without breaking it.
*/
function clientCode(AbstractFactory $factory)
{
$productA = $factory->createProductA();
$productB = $factory->createProductB();
echo $productB->usefulFunctionB() . "\n";
echo $productB->anotherUsefulFunctionB($productA) . "\n";
}
/**
* The client code can work with any concrete factory class.
*/
echo "Client: Testing client code with the first factory type:\n";
clientCode(new ConcreteFactory1());
echo "\n";
echo "Client: Testing the same client code with the second factory type:\n";
clientCode(new ConcreteFactory2());
** Output.txt: 执行结果
Client: Testing client code with the first factory type:
The result of the product B1.
The result of the B1 collaborating with the (The result of the product A1.)
Client: Testing the same client code with the second factory type:
The result of the product B2.
The result of the B2 collaborating with the (The result of the product A2.)
