AI 助理
文档备案控制台
开发者社区 开发与运维 文章 正文

PHP面向对象深入研究之【继承】，减少代码重复

2017-01-29 989
版权
版权声明：
本文内容由阿里云实名注册用户自发贡献，版权归原作者所有，阿里云开发者社区不拥有其著作权，亦不承担相应法律责任。具体规则请查看《 阿里云开发者社区用户服务协议》和 《阿里云开发者社区知识产权保护指引》。如果您发现本社区中有涉嫌抄袭的内容，填写 侵权投诉表单进行举报，一经查实，本社区将立刻删除涉嫌侵权内容。
简介：

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。



本文转自TBHacker博客园博客，原文链接：http://www.cnblogs.com/jiqing9006/p/5169350.html，如需转载请自行联系原作者


文章标签：
PHP
关键词：
PHP代码
PHP对象
PHP面向对象
PHP面向对象继承
PHP继承
桃子红了呐
目录
相关文章
多客潇潇
|
消息中间件 缓存 弹性计算
纯PHP+MySQL手搓高性能论坛系统！代码精简，拒绝臃肿
本内容分享了一套经实战验证的社交系统架构设计，支撑从1到100万用户的发展，并历经6次流量洪峰考验。架构涵盖客户端层（App、小程序、公众号）、接入层（API网关、负载均衡、CDN）、业务服务层（用户、内容、关系、消息等服务）、数据层（MySQL、Redis、MongoDB等）及运维监控层（日志、监控、告警）。核心设计包括数据库分库分表、多级缓存体系、消息队列削峰填谷、CQRS模式与热点数据动态缓存。同时提供应对流量洪峰的弹性伸缩方案及降级熔断机制，并通过Prometheus实现全链路监控。开源建议结构清晰，适合大型社交平台构建与优化。
多客潇潇
530 11
陌陌谣
|
监控 算法 安全
基于 PHP 语言深度优先搜索算法的局域网网络监控软件研究
在当下数字化时代，局域网作为企业与机构内部信息交互的核心载体，其稳定性与安全性备受关注。局域网网络监控软件随之兴起，成为保障网络正常运转的关键工具。此类软件的高效运行依托于多种数据结构与算法，本文将聚焦深度优先搜索（DFS）算法，探究其在局域网网络监控软件中的应用，并借助 PHP 语言代码示例予以详细阐释。
陌陌谣
336 1
陌陌谣
|
9月前
|
存储 监控 算法
基于 PHP 布隆过滤器的局域网监控管理工具异常行为检测算法研究
布隆过滤器以其高效的空间利用率和毫秒级查询性能，为局域网监控管理工具提供轻量化异常设备检测方案。相比传统数据库，显著降低延迟与资源消耗，适配边缘设备部署需求，提升网络安全实时防护能力。（238字）
陌陌谣
306 0
1842782014377483
|
IDE PHP 开发工具
PHP中的类型提示与严格模式：提高代码可维护性
随着PHP语言的发展，开发者对代码的可读性、可维护性和可靠性有了更高的要求。PHP中的类型提示（Type Hinting）和严格模式（Strict Mode）为开发者提供了更强的类型检查机制，有助于提升代码质量和减少潜在的错误，尤其是在大型项目中。
1842782014377483
411 1
卓伊凡
|
12月前
|
存储 缓存 安全
php项目源码加密之Zend Guard Loader加密的代码解密可能性很小-优雅草卓伊凡
php项目源码加密之Zend Guard Loader加密的代码解密可能性很小-优雅草卓伊凡
卓伊凡
532 2
陌陌谣
|
监控 算法 安全
基于 PHP 的员工电脑桌面监控软件中图像差分算法的设计与实现研究
本文探讨了一种基于PHP语言开发的图像差分算法，用于员工计算机操作行为监控系统。算法通过分块比较策略和动态阈值机制，高效检测屏幕画面变化，显著降低计算复杂度与内存占用。实验表明，相比传统像素级差分算法，该方法将处理时间缩短88%，峰值内存使用量减少70%。文章还介绍了算法在工作效率优化、信息安全防护等方面的应用价值，并分析了数据隐私保护、算法准确性及资源消耗等挑战。未来可通过融合深度学习等技术进一步提升系统智能化水平。
陌陌谣
201 2
陌陌谣
|
存储 监控 算法
基于 PHP 语言的滑动窗口频率统计算法在公司局域网监控电脑日志分析中的应用研究
在当代企业网络架构中，公司局域网监控电脑系统需实时处理海量终端设备产生的连接日志。每台设备平均每分钟生成 3 至 5 条网络请求记录，这对监控系统的数据处理能力提出了极高要求。传统关系型数据库在应对这种高频写入场景时，性能往往难以令人满意。故而，引入特定的内存数据结构与优化算法成为必然选择。
陌陌谣
372 3
muxiaoxi
|
PHP 开发者 容器
PHP命名空间深度解析：避免命名冲突与提升代码组织####
本文深入探讨了PHP中命名空间的概念、用途及最佳实践，揭示其在解决全局命名冲突、提高代码可维护性方面的重要性。通过生动实例和详尽分析，本文将帮助开发者有效利用命名空间来优化大型项目结构，确保代码的清晰与高效。 ####
muxiaoxi
270 20
左诗右码
|
供应链 安全 NoSQL
PHP 互斥锁：如何确保代码的线程安全？
在多线程和高并发环境中，确保代码段互斥执行至关重要。本文介绍了 PHP 互斥锁库 `wise-locksmith`，它提供多种锁机制（如文件锁、分布式锁等），有效解决线程安全问题，特别适用于电商平台库存管理等场景。通过 Composer 安装后，开发者可以利用该库确保在高并发下数据的一致性和安全性。
左诗右码
314 6
shuj
|
PHP 开发者 UED
探索PHP中的异常处理：提升代码的健壮性
在PHP开发中，优雅地处理错误和异常是确保应用稳定性和用户体验的关键。本文将通过深入浅出的方式，介绍如何在PHP中实现有效的异常处理机制，包括异常的基本概念、如何抛出和捕获异常，以及最佳实践。准备好让你的代码变得更加健壮和可靠吧！
shuj
220 2