<?php class CdProduct { public $playLength; // 播放时间 public $title; public $producerMainName; public $producerFirstName; public $price; function __construct( $title, $firstName, $mainName, $price, $playLength ) { $this->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"; ?>
输出：
cd1 ( bobbleson, bob ): playing time - 50
book1 ( harrelson, harry ): page count - 30
点评：这两个类，代码重复性太高，有相同性，也有差异性。不如用继承来简化处理。
采用继承来处理
<?php class ShopProduct { public $numPages; public $playLength; public $title; public $producerMainName; public $producerFirstName; public $price; function __construct( $title, $firstName, $mainName, $price, $numPages=0, $playLength=0 ) { $this->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"; ?>
输出：
cd1 ( bobbleson, bob ): playing time - 50
book1 ( harrelson, harry ): page count - 30
点评：继承处理很好的解决了差异性，相通性问题。
进一步优化处理
<?php class ShopProduct { // 抽离出共有属性 public $title; public $producerMainName; public $producerFirstName; public $price; function __construct( $title, $firstName, $mainName, $price ) { $this->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"; ?>
输出：
cd1 ( bobbleson, bob ): playing time - 50
book1 ( harrelson, harry ): page count - 30
点评：这里把共有属性在父类中，其他个性属性放在自己的类中处理。并设置自己的构造方法，继承父类的构造方法。
进一步继承父类的方法