這篇文章主要介紹了PHP物件導向繼承用法,結合實例形式分析了php物件導向程式設計中繼承的使用方法及程式碼最佳化處理與減少程式碼重複的相關操作技巧,需要的朋友可以參考下
本文實例講述了PHP物件導向繼承用法。分享給大家供大家參考，具體如下：
繼承
#先看兩個類別
title = $title; $this->producerFirstName = $firstName; $this->producerMainName = $mainName; $this->price = $price; $this->playLength = $playLength; } function getPlayLength() { return $this->playLength; } function getSummaryLine() { $base = "{$this->title} ( {$this->producerMainName}, "; $base .= "{$this->producerFirstName} )"; $base .= ": playing time - {$this->playLength}"; return $base; } function getProducer() { return "{$this->producerFirstName}". " {$this->producerMainName}"; } } class BookProduct { public $numPages; // 看的页数 public $title; public $producerMainName; public $producerFirstName; public $price; function __construct( $title, $firstName, $mainName, $price, $numPages ) { $this->title = $title; $this->producerFirstName = $firstName; $this->producerMainName = $mainName; $this->price = $price; $this->numPages = $numPages; } function getNumberOfPages() { return $this->numPages; } function getSummaryLine() { $base = "{$this->title} ( {$this->producerMainName}, "; $base .= "{$this->producerFirstName} )"; $base .= ": page count - {$this->numPages}"; return $base; } function getProducer() { return "{$this->producerFirstName}". " {$this->producerMainName}"; } } $product1 = new CdProduct("cd1", "bob", "bobbleson", 4, 50 ); print $product1->getSummaryLine(); print "\n"; $product2 = new BookProduct("book1", "harry", "harrelson", 4, 30 ); print $product2->getSummaryLine(); print "\n"; ?>
#輸出：
#cd1 ( bobbleson, bob ): playing time - 50
book1 ( harrelson, harry ): page count - 30
評論：這兩個類，程式碼重複性太高，有相同性，也有差異性。不如用繼承來簡化處理。
採用繼承來處理
title = $title; $this->producerFirstName = $firstName; $this->producerMainName = $mainName; $this->price = $price; $this->numPages = $numPages; $this->playLength = $playLength; } function getProducer() { return "{$this->producerFirstName}". " {$this->producerMainName}"; } function getSummaryLine() { $base = "$this->title ( {$this->producerMainName}, "; $base .= "{$this->producerFirstName} )"; return $base; } } class CdProduct extends ShopProduct { function getPlayLength() { // 增加属于自己的方法 return $this->playLength; } function getSummaryLine() { // 改造了父类的方法 $base = "{$this->title} ( {$this->producerMainName}, "; $base .= "{$this->producerFirstName} )"; $base .= ": playing time - {$this->playLength}"; return $base; } } class BookProduct extends ShopProduct { function getNumberOfPages() { return $this->numPages; } function getSummaryLine() { $base = "{$this->title} ( {$this->producerMainName}, "; $base .= "{$this->producerFirstName} )"; $base .= ": page count - {$this->numPages}"; return $base; } } $product1 = new CdProduct("cd1", "bob", "bobbleson", 4, null, 50 ); print $product1->getSummaryLine(); print "\n"; $product2 = new BookProduct("book1", "harry", "harrelson", 4, 30 ); print $product2->getSummaryLine(); print "\n"; ?>
輸出：
cd1 ( bobbleson, bob ): playing time - 50
book1 ( harrelson, harry ): page count - 30
點評：繼承處理很好的解決了差異性，相通性問題。
進一步最佳化處理
title = $title; $this->producerFirstName = $firstName; $this->producerMainName = $mainName; $this->price = $price; } function getProducer() { return "{$this->producerFirstName}". " {$this->producerMainName}"; } function getSummaryLine() { $base = "{$this->title} ( {$this->producerMainName}, "; $base .= "{$this->producerFirstName} )"; return $base; } } class CdProduct extends ShopProduct { // 抽离出属于自己特有的属性 public $playLength; function __construct( $title, $firstName, $mainName, $price, $playLength ) { parent::__construct( $title, $firstName, $mainName, $price ); // 继承父类的构造函数 $this->playLength = $playLength; // 处理自己专有的属性 } function getPlayLength() { return $this->playLength; } function getSummaryLine() { $base = "{$this->title} ( {$this->producerMainName}, "; $base .= "{$this->producerFirstName} )"; $base .= ": playing time - {$this->playLength}"; return $base; } } class BookProduct extends ShopProduct { public $numPages; function __construct( $title, $firstName, $mainName, $price, $numPages ) { parent::__construct( $title, $firstName, $mainName, $price ); $this->numPages = $numPages; } function getNumberOfPages() { return $this->numPages; } function getSummaryLine() { $base = "$this->title ( $this->producerMainName, "; $base .= "$this->producerFirstName )"; $base .= ": page count - $this->numPages"; return $base; } } $product1 = new CdProduct("cd1", "bob", "bobbleson", 4, 50 ); print $product1->getSummaryLine(); print "\n"; $product2 = new BookProduct("book1", "harry", "harrelson", 4, 30 ); print $product2->getSummaryLine(); print "\n"; ?>
輸出：
cd1 ( bobbleson, bob ): playing time - 50
book1 ( harrelson, harry ): page count - 30
點評：這裡把共有屬性在父類別中，其他個性屬性放在自己的類別中處理。並且設定自己的建構方法，繼承父類別的建構方法。
進一步繼承父類別的方法
title = $title; $this->producerFirstName = $firstName; $this->producerMainName = $mainName; $this->price = $price; } function getProducer() { return "{$this->producerFirstName}". " {$this->producerMainName}"; } function getSummaryLine() { $base = "{$this->title} ( {$this->producerMainName}, "; $base .= "{$this->producerFirstName} )"; return $base; } } class CdProduct extends ShopProduct { public $playLength; function __construct( $title, $firstName, $mainName, $price, $playLength ) { parent::__construct( $title, $firstName, $mainName, $price ); $this->playLength = $playLength; } function getPlayLength() { return $this->playLength; } function getSummaryLine() { $base = parent::getSummaryLine(); $base .= ": playing time - {$this->playLength}"; return $base; } } class BookProduct extends ShopProduct { public $numPages; function __construct( $title, $firstName, $mainName, $price, $numPages ) { parent::__construct( $title, $firstName, $mainName, $price ); $this->numPages = $numPages; } function getNumberOfPages() { return $this->numPages; } function getSummaryLine() { $base = parent::getSummaryLine(); $base .= ": page count - {$this->numPages}"; return $base; } } $product1 = new CdProduct("cd1", "bob", "bobbleson", 4, 50 ); print $product1->getSummaryLine(); print "\n"; $product2 = new BookProduct("book1", "harry", "harrelson", 4, 30 ); print $product2->getSummaryLine(); print "\n"; ?>
輸出：
cd1 ( bobbleson, bob ): playing time - 50
book1 ( harrelson, harry ): page count - 30
評論：同樣的結果，可以優化優化再優化。這裡繼承父類別的方法。 parent::getSummaryLine()。不過這個用的比較少。
繼續加入一些有趣的內容
title = $title; $this->producerFirstName = $firstName; $this->producerMainName = $mainName; $this->price = $price; } function setDiscount( $num ) { $this->discount=$num; } function getPrice() { return ($this->price - $this->discount); } function getProducer() { return "{$this->producerFirstName}". " {$this->producerMainName}"; } function getSummaryLine() { $base = "{$this->title} ( {$this->producerMainName}, "; $base .= "{$this->producerFirstName} )"; return $base; } } class CdProduct extends ShopProduct { public $playLength; function __construct( $title, $firstName, $mainName, $price, $playLength ) { parent::__construct( $title, $firstName, $mainName, $price ); $this->playLength = $playLength; } function getPlayLength() { return $this->playLength; } function getSummaryLine() { $base = parent::getSummaryLine(); $base .= ": playing time - {$this->playLength}"; return $base; } } class BookProduct extends ShopProduct { public $numPages; function __construct( $title, $firstName, $mainName, $price, $numPages ) { parent::__construct( $title, $firstName, $mainName, $price ); $this->numPages = $numPages; } function getPrice() { return $this->price; } function getNumberOfPages() { return $this->numPages; } function getSummaryLine() { $base = parent::getSummaryLine(); $base .= ": page count - {$this->numPages}"; return $base; } } $product1 = new CdProduct("cd1", "bob", "bobbleson", 4, 50 ); $product1->setDiscount( 3 ); print $product1->getSummaryLine(); print "\n"; print "price: {$product1->getPrice()}\n"; $product2 = new BookProduct("book1", "harry", "harrelson", 4, 30 ); $product2->setDiscount( 3 ); // 折扣对book无效 print $product2->getSummaryLine(); print "\n"; print "price: {$product2->getPrice()}\n"; ?>
price: 1
book1 ( harrelson, harry ): page count - 30
price: 4
私有化屬性，透過方法來設定與取得
title = $title; $this->producerFirstName = $firstName; $this->producerMainName = $mainName; $this->price = $price; } public function getProducerFirstName() { return $this->producerFirstName; } public function getProducerMainName() { return $this->producerMainName; } public function setDiscount( $num ) { $this->discount=$num; } public function getDiscount() { return $this->discount; } public function getTitle() { return $this->title; } public function getPrice() { return ($this->price - $this->discount); } public function getProducer() { return "{$this->producerFirstName}". " {$this->producerMainName}"; } public function getSummaryLine() { $base = "{$this->title} ( {$this->producerMainName}, "; $base .= "{$this->producerFirstName} )"; return $base; } } class CdProduct extends ShopProduct { private $playLength = 0; public function __construct( $title, $firstName, $mainName, $price, $playLength ) { parent::__construct( $title, $firstName, $mainName, $price ); $this->playLength = $playLength; } public function getPlayLength() { return $this->playLength; } public function getSummaryLine() { $base = parent::getSummaryLine(); $base .= ": playing time - {$this->playLength}"; return $base; } } class BookProduct extends ShopProduct { private $numPages = 0; public function __construct( $title, $firstName, $mainName, $price, $numPages ) { parent::__construct( $title, $firstName, $mainName, $price ); $this->numPages = $numPages; } public function getNumberOfPages() { return $this->numPages; } public function getSummaryLine() { $base = parent::getSummaryLine(); $base .= ": page count - {$this->numPages}"; return $base; } public function getPrice() { return $this->price; } } $product1 = new CdProduct("cd1", "bob", "bobbleson", 4, 50 ); print $product1->getSummaryLine()."\n"; $product2 = new BookProduct("book1", "harry", "harrelson", 4, 30 ); print $product2->getSummaryLine()."\n"; ?>
book1 ( harrelson, harry ): page count - 30
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