《PHP教程：PHP面向?qū)ο罄^承用法詳解(優(yōu)化與減少代碼重復(fù))》要點：
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PHP編程本文實例講述了PHP面向?qū)ο罄^承用法.分享給大家供大家參考,具體如下：
PHP編程繼承
PHP編程先看兩個類
PHP編程
<?php
class CdProduct {
public $playLength; // 播放時間
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; // 看的頁數(shù)
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";
?>
PHP編程輸出：
PHP編程cd1 ( bobbleson, bob ): playing time - 50
book1 ( harrelson, harry ): page count - 30
PHP編程點評：這兩個類,代碼重復(fù)性太高,有相同性,也有差異性.不如用繼承來簡化處理.
PHP編程采用繼承來處理
PHP編程
<?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() { // 增加屬于自己的方法
return $this->playLength;
}
function getSummaryLine() { // 改造了父類的方法
$base = "{$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";
?>
PHP編程輸出：
PHP編程cd1 ( bobbleson, bob ): playing time - 50
book1 ( harrelson, harry ): page count - 30
PHP編程點評：繼承處理很好的解決了差異性,相通性問題.
PHP編程進一步優(yōu)化處理
PHP編程
<?php
class ShopProduct {
// 抽離出共有屬性
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 {
// 抽離出屬于自己特有的屬性
public $playLength;
function __construct( $title, $firstName,
$mainName, $price, $playLength ) {
parent::__construct( $title, $firstName,
$mainName, $price ); // 繼承父類的構(gòu)造函數(shù)
$this->playLength = $playLength; // 處理自己專有的屬性
}
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";
?>
PHP編程輸出：
PHP編程cd1 ( bobbleson, bob ): playing time - 50
book1 ( harrelson, harry ): page count - 30
PHP編程點評：這里把共有屬性在父類中,其他個性屬性放在自己的類中處理.并設(shè)置自己的構(gòu)造方法,繼承父類的構(gòu)造方法.
PHP編程進一步繼承父類的方法
PHP編程
<?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";
?>
PHP編程輸出：
PHP編程cd1 ( bobbleson, bob ): playing time - 50
book1 ( harrelson, harry ): page count - 30
PHP編程點評：同樣的結(jié)果,可以優(yōu)化優(yōu)化再優(yōu)化.這里繼承父類的方法.parent::getSummaryLine().不過這個用的比較少.
PHP編程繼續(xù)添加一些有意思的內(nèi)容
PHP編程
<?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 ); // 折扣對book無效
print $product2->getSummaryLine();
print "\n";
print "price: {$product2->getPrice()}\n";
?>
PHP編程輸出：
PHP編程cd1 ( bobbleson, bob ): playing time - 50
price: 1
book1 ( harrelson, harry ): page count - 30
price: 4
PHP編程點評:父類添加了折扣,book繼承之后,修改了getPrice方法,所以折扣對book無效.
PHP編程私有化屬性,通過方法來設(shè)置與獲取
PHP編程
<?php
class ShopProduct {
// 私有化屬性,通過方法來設(shè)置與獲取
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";
?>
PHP編程輸出：
PHP編程cd1 ( bobbleson, bob ): playing time - 50
book1 ( harrelson, harry ): page count - 30
PHP編程點評：這里進一步私有化了屬性,要想獲取只能通過方法.這樣就確保了安全性.
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