在開發(fā)大型系統(tǒng)時(shí),往往會(huì)出現(xiàn)這樣一種情況:
我有一部分基礎(chǔ)數(shù)據(jù),是類classA是從數(shù)據(jù)庫(kù)A讀取出來(lái)的,其他很多的功能都是基于這個(gè)基礎(chǔ)數(shù)據(jù)來(lái)操作的。現(xiàn)在呢,我想把數(shù)據(jù)從數(shù)據(jù)庫(kù)A變成從另外的數(shù)據(jù)源去獲取,這時(shí)候,要修改起來(lái)就比較麻煩,要修改其他很多類的代碼。這種設(shè)計(jì)顯然是不夠靈活的,換句話說(shuō),就是緊耦合的,那么什么是緊耦合呢?緊耦合就是指系統(tǒng)中某個(gè)部分的函數(shù)或類嚴(yán)重依賴于系統(tǒng)的其他部分中的函數(shù)或類的行為和結(jié)構(gòu)。
這時(shí),工廠模式的作用性就體現(xiàn)出來(lái)了。
工廠模式
就是解決這樣的一些情況的設(shè)計(jì)方法。
工廠模式是一種類,建立了一個(gè)工廠來(lái)根據(jù)所需來(lái)創(chuàng)建對(duì)象,這種方式在多態(tài)性編程中是很重要的,允許動(dòng)態(tài)替換類,修改配置等。
/*基本工廠模式代碼*/
<?php /** * 基本工廠模式 * */ class User { private $username; public function __construct($username) { $this->username = $username; } public function getUser() { return $this->username; } } class userFactory { static public function createUser() { return new User('Jack'); } } $user = userFactory::createUser();echo $user->getUser(); ?>
工廠模式分為:簡(jiǎn)單工廠模式、工廠方法模式、抽象工廠模式。
簡(jiǎn)單工廠模式,通過(guò)靜態(tài)方法創(chuàng)建對(duì)象。可以理解成,只負(fù)責(zé)生產(chǎn)同一等級(jí)結(jié)構(gòu)中的任何一個(gè)產(chǎn)品,但是不能新增產(chǎn)品。
<?php /** *簡(jiǎn)單工廠模式 * */ interface userProperties { function getUsername(); function getGender(); function getJob(); } class User implements userProperties{ private $username; private $gender; private $job; public function __construct($username, $gender, $job) { $this->username = $username; $this->gender = $gender; $this->job = $job; } public function getUsername() { return $this->username; } public function getGender() { return $this->gender; } public function getJob() { return $this->job; } } class userFactory { static public function createUser($properties = []) { return new User($properties['username'], $properties['gender'], $properties['job']); } } $employers = [ ['username' => 'Jack', 'gender' => 'male', 'job' => 'coder'], ['username' => 'Marry', 'gender' => 'female', 'job' => 'designer'], ]; $user = userFactory::createUser($employers[0]); echo $user->getUsername(); ?>
工廠方法模式,去掉了簡(jiǎn)單工廠模式中方法的靜態(tài)屬性,使其可以被子類集成,定義一個(gè)創(chuàng)建對(duì)象的接口,讓子類去決定實(shí)例化哪個(gè)類。可以理解成,用來(lái)生產(chǎn)同一等級(jí)結(jié)構(gòu)中的固定產(chǎn)品,但是支持增加產(chǎn)品。
<?php /** * 工廠方法模式 **/ interface userProperties { function getUsername(); function getGender(); function getJob(); } interface createUser { function create($properties); } class User implements userProperties{ private $username; private $gender; private $job; public function __construct($username, $gender, $job) { $this->username = $username; $this->gender = $gender; $this->job = $job; } public function getUsername() { return $this->username; } public function getGender() { return $this->gender; } public function getJob() { return $this->job; } } class userFactory { private $user; public function __construct($properties = []) { $this->user = new User($properties['username'], $properties['gender'], $properties['job']); } public function getUser() { return $this->user; } } class FactoryMan implements createUser { function create($properties) { return new userFactory($properties); } } class FactoryWoman implements createUser { function create($properties) { return new userFactory($properties); } } class clientUser { static public function getClient($properties) { $fac = new FactoryMan; $man = $fac->create($properties); echo $man->getUser()->getUsername(); } } $employers = [ ['username' => 'Jack', 'gender' => 'male', 'job' => 'coder'], ['username' => 'Marry', 'gender' => 'female', 'job' => 'designer'], ]; $user = clientUser::getClient($employers[0]); ?>
抽象工廠模式,提供一個(gè)創(chuàng)建一系列相關(guān)或者相互依賴的對(duì)象的接口。可以理解成,用來(lái)生產(chǎn)不用類型的全部產(chǎn)品,但是不能增加新品,支持增加新的類型。
<?php /** * 抽象工廠模式 * */ interface userProperties { function getUsername(); function getGender(); function getJob(); } interface createUser { //將對(duì)象的創(chuàng)建抽象成一個(gè)接口 function createOpen($properties);//內(nèi)向創(chuàng)建 function createIntro($properties);//外向創(chuàng)建 } class User implements userProperties{ private $username; private $gender; private $job; public function __construct($username, $gender, $job) { $this->username = $username; $this->gender = $gender; $this->job = $job; } public function getUsername() { return $this->username; } public function getGender() { return $this->gender; } public function getJob() { return $this->job; } } class userFactory { private $user; public function __construct($properties = []) { $this->user = new User($properties['username'], $properties['gender'], $properties['job']); } public function getUser() { return $this->user; } } class FactoryMan implements createUser { function createOpen($properties) { return new userFactory($properties); } function createIntro($properties) { return new userFactory($properties); } } class FactoryWoman implements createUser { function createOpen($properties) { return new userFactory($properties); } function createIntro($properties) { return new userFactory($properties); } } class clientUser { static public function getClient($properties) { $fac = new FactoryMan; $man = $fac->createOpen($properties); echo $man->getUser()->getUsername(); } } $employers = [ ['username' => 'Jack', 'gender' => 'male', 'job' => 'coder'], ['username' => 'Marry', 'gender' => 'female', 'job' => 'designer'], ]; $user = clientUser::getClient($employers[0]); ?>
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