PHP设计模式范例 — DesignPatternsPHP（2）结构型设计模式

jiezi

6 年前

【搬运于 GitHub 开源项目 DesignPatternsPHP】
项目地址：戳我

2、结构型设计模式
在软件工程中，结构型设计模式集是用来抽象真实程序中的对象实体之间的关系，并使这种关系可被描述，概括和具体化。
2.1 适配器模式
2.1.1 目的
将某个类的接口转换成与另一个接口兼容。适配器通过将原始接口进行转换，给用户提供一个兼容接口，使得原来因为接口不同而无法一起使用的类可以得到兼容。
2.1.2 例子

数据库客户端库适配器
使用不同的 webservices，通过适配器来标准化输出数据，从而保证不同 webservice 输出的数据是一致的

2.1.3 UML 图

2.1.4 代码
你可以在 GitHub 上找到这些代码
BookInterface.php
<?php

namespace DesignPatterns\Structural\Adapter;

interface BookInterface
{
public function turnPage();

public function open();

public function getPage(): int;
}
Book.php
<?php

namespace DesignPatterns\Structural\Adapter;

class Book implements BookInterface
{
/**
* @var int
*/
private $page;

public function open()
{
$this->page = 1;
}

public function turnPage()
{
$this->page++;
}

public function getPage(): int
{
return $this->page;
}
}
EBookAdapter.php
<?php

namespace DesignPatterns\Structural\Adapter;

/**
* This is the adapter here. Notice it implements BookInterface,
* therefore you don’t have to change the code of the client which is using a Book
*/
class EBookAdapter implements BookInterface
{
/**
* @var EBookInterface
*/
protected $eBook;

/**
* @param EBookInterface $eBook
*/
public function __construct(EBookInterface $eBook)
{
$this->eBook = $eBook;
}

/**
* This class makes the proper translation from one interface to another.
*/
public function open()
{
$this->eBook->unlock();
}

public function turnPage()
{
$this->eBook->pressNext();
}

/**
* notice the adapted behavior here: EBookInterface::getPage() will return two integers, but BookInterface
* supports only a current page getter, so we adapt the behavior here
*
* @return int
*/
public function getPage(): int
{
return $this->eBook->getPage()[0];
}
}
EBookInterface.php
<?php

namespace DesignPatterns\Structural\Adapter;

interface EBookInterface
{
public function unlock();

public function pressNext();

/**
* returns current page and total number of pages, like [10, 100] is page 10 of 100
*
* @return int[]
*/
public function getPage(): array;
}
Kindle.php
<?php

namespace DesignPatterns\Structural\Adapter;

/**
* this is the adapted class. In production code, this could be a class from another package, some vendor code.
* Notice that it uses another naming scheme and the implementation does something similar but in another way
*/
class Kindle implements EBookInterface
{
/**
* @var int
*/
private $page = 1;

/**
* @var int
*/
private $totalPages = 100;

public function pressNext()
{
$this->page++;
}

public function unlock()
{
}

/**
* returns current page and total number of pages, like [10, 100] is page 10 of 100
*
* @return int[]
*/
public function getPage(): array
{
return [$this->page, $this->totalPages];
}
}
2.2 桥接模式
2.2.1 目的
解耦一个对象的实现与抽象，这样两者可以独立地变化。
2.2.2 例子
Symfony DoctrineBridge
2.2.3 UML 图

2.2.4 代码
你可以在 GitHub 上找到这些代码
Formatter.php
<?php