PHP 设计模式系列 —— 静态工厂模式(Static Factory)

1、模式定义

与简单工厂类似,该模式用于创建一组相关或依赖的对象,不同之处在于静态工厂模式使用一个静态方法来创建所有类型的对象,该静态方法通常是 factory 或  build

2、UML类图

静态工厂模式类图

3、示例代码

StaticFactory.php

<?php

namespace DesignPatterns\Creational\StaticFactory;

class StaticFactory
{
    /**
     * 通过传入参数创建相应对象实例
     *
     * @param string $type
     *
     * @static
     *
     * @throws \InvalidArgumentException
     * @return FormatterInterface
     */
    public static function factory($type)
    {
        $className = __NAMESPACE__ . '\Format' . ucfirst($type);

        if (!class_exists($className)) {
            throw new \InvalidArgumentException('Missing format class.');
        }

        return new $className();
    }
}

FormatterInterface.php

<?php

namespace DesignPatterns\Creational\StaticFactory;

/**
 * FormatterInterface接口
 */
interface FormatterInterface
{
}

FormatString.php

<?php

namespace DesignPatterns\Creational\StaticFactory;

/**
 * FormatNumber类
 */
class FormatNumber implements FormatterInterface
{
}

4、测试代码

Tests/StaticFactoryTest.php

<?php

namespace DesignPatterns\Creational\StaticFactory\Tests;

use DesignPatterns\Creational\StaticFactory\StaticFactory;

/**
 * 测试静态工厂模式
 *
 */
class StaticFactoryTest extends \PHPUnit_Framework_TestCase
{

    public function getTypeList()
    {
        return array(
            array('string'),
            array('number')
        );
    }

    /**
     * @dataProvider getTypeList
     */
    public function testCreation($type)
    {
        $obj = StaticFactory::factory($type);
        $this->assertInstanceOf('DesignPatterns\Creational\StaticFactory\FormatterInterface', $obj);
    }

    /**
     * @expectedException InvalidArgumentException
     */
    public function testException()
    {
        StaticFactory::factory("");
    }
}

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