实例分析PHP面向对象继承用法(优化与减少代码重复)
- 更新时间:2020-03-13 12:15:27
- 编辑:卢清绮
本文实例讲述了PHP面向对象继承用法。分享给大家供大家参考,具体如下:
继承
先看两个类
<?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
<?php class ShopProduct { 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 { 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"; ?>
输出:
cd1 ( bobbleson, bob ): playing time - 50
book1 ( harrelson, harry ): page count - 30
点评:同样的结果,可以优化优化再优化。这里继承父类的方法。parent::getSummaryLine()。不过这个用的比较少。
继续添加一些有意思的内容
<?php class ShopProduct { private $title; private $discount = 0; private $producerMainName; private $producerFirstName; protected $price; function __construct( $title, $firstName, $mainName, $price ) { $this->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"; ?>
输出:
cd1 ( bobbleson, bob ): playing time - 50
price: 1
book1 ( harrelson, harry ): page count - 30
price: 4
点评:父类添加了折扣,book继承之后,修改了getPrice方法,所以折扣对book无效。
私有化属性,通过方法来设置与获取
<?php class ShopProduct { // 私有化属性,通过方法来设置与获取 private $title; private $producerMainName; private $producerFirstName; protected $price; private $discount = 0; public function __construct( $title, $firstName, $mainName, $price ) { $this->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"; ?>
输出:
cd1 ( bobbleson, bob ): playing time - 50
book1 ( harrelson, harry ): page count - 30
点评:这里进一步私有化了属性,要想获取只能通过方法。这样就确保了安全性。
更多关于PHP相关内容感兴趣的读者可查看本站专题:《php面向对象程序设计入门教程》、《PHP基本语法入门教程》、《PHP运算与运算符用法总结》、《PHP网络编程技巧总结》、《PHP数组(Array)操作技巧大全》、《php字符串(string)用法总结》、《php+mysql数据库操作入门教程》及《php常见数据库操作技巧汇总》
希望本文所述对大家PHP程序设计有所帮助。
相关教程
-
PHP打印输出函数汇总
本文给大家汇总介绍了7种php常用的打印输出函数,分别是echo,print,printf,sprintf,print_r,var_dump,die,希望对大家学习php能够有所帮助
发布时间:2019-08-28
-
PHP利用Mysql锁解决高并发的方法
这篇文章主要介绍了PHP利用Mysql锁解决高并发的方法,小编觉得挺不错的,现在分享给大家,也给大家做个参考。一起跟随小编过来看看吧
发布时间:2019-06-05
-
PHP和MySQL Web开发(第5版)
在《PHP和MySQL Web开发》书中,我们将把使用PHP与MySQL的经验和心得体会毫无保留地分享给你,PHP和MySQL是目前热门的两个Web开发工具。
大小:27 MB网站开发电子书
-
Learning PHP设计模式
本书是PHP设计模式的经典教程,让读者掌握更精巧的编程风格。本书利用大量浅显易懂的例子告诉你如何应用多种面向对象模式,并展示了这些模式在一些成熟的实际项目中的具体应用,欢迎免费下载
大小:39.4 MBPHP编程电子书
-
PHP+MySQL程序设计及项目开发
大小:105.1MBPHP+MySQL
-
PHP Zend Framework项目开发基础案例教程
《PHP Zend Framework项目开发基础案例教程》以实际项目——XX办公自动化管理系统的开发——为案例,详细介绍使用PHP的企业级框架Zend Framework进行Web应用开发的步骤及关键技术。全书共12章
大小:65 MBPHP电子书
-
PHP 7 编程实战
PHP7挟很多的、强劲的新作用和小工具强劲而成,应用这种作用和小工具能够 提升编码,编写出比老PHP版本号程序流程速度相当快的程序流程。这书主要详细介绍了PHP7有关的高级PHP编程技术。
大小:11.2 MBPHP7电子书
-
PHP与MySQL高性能应用开发
PHP与MySQL高性能应用开发书中不仅讲解了OOP、设计模式,也讲解了如何进行性能优化和调试。甚至,还对于语言之外的代码重构进行了讲解,本书面向的对象是有一定PHP基础,但是又想深入学习的PHP开发者,欢迎免费下载
大小:60.5 MBPHP开发电子书
-
PHP&MySQL跨设备网站开发实例精粹
这本书从易学实用的角度详细讲解了PHP、HTML5语法,MySQL数据库存取,网页之间的信息传递、表单的后端处理等,提供了丰富的网站开发范例,欢迎下载
大小:80.9 MBPHP编程电子书
-
PHP开发实例大全:基础卷
《PHP开发实例大全》625经典实例及源码分析 15个应用方向 两卷共1225例 40个方向 分门别类实例一应俱全 供学习、速查、实践练习的超全参考手册 php开发实战1200例 php范例大全之全新升级。
大小:232 MBPHP开发电子书