本文实例讲述了PHP面向对象程序设计高级特性。分享给大家供大家参考，具体如下：
高级特性
包括：
1.静态方法和属性（通过类而不是对象来访问数据和功能）
2.抽象类和接口（设计，实现分离）
3.错误处理（异常）
4.Final类和方法（限制继承）
5.拦截器（自动委托）
6.析构方法（对象销毁前的清理工作）
7.克隆对象（创建对象的副本）
8.把对象解析成字符串
PS，学会从内存的角度看代码。想象计算机的微观世界。
静态方法的小例子
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<?phpclass StaticExample{ static public $aNum = 10; static public function sayHello(){ print "hello"; }}print StaticExample::$aNum."<br/>";StaticExample::sayHello(); |
tips:
1.静态方法不能访问类中的普通属性，因为那些属性属于一个对象，但可以访问静态属性。
2.我们不能再对象中调用静态方法，因此不能再静态方法中使用伪变量$this。
静态方法的大例子
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<?phpclass ShopProduct{ private $title; private $producerMainName; private $producerFirstName; protected $price; private $discount = 0; private $id = 0; function __construct($title,$firstName,$mainName,$price){ $this->title = $title; $this->producerFirstName = $firstName; $this->producerMainName = $mainName; $this->price = $price; } public function setID($id){ $this->id = $id; } public static function getInstance($id,PDO $pdo){ $query = "select * from products where id= '$id'"; $stmt = $pdo->query($query); $row = $stmt->fetch(); if(empty($row)){ return null; } if($row['type'] == "book"){ $product = new BookProduct($row['title'], $row['firstname'], $row['mainname'], $row['price'], $row['numpages'] ); }else if($row['type'] == "cd"){ $product = new CdProduct($row['title'], $row['firstname'], $row['mainname'], $row['price'], $row['playLength'] ); }else{ $product = new ShopProduct($row['title'], $row['firstname'], $row['mainname'], $row['price'] ); } $product->setId($row['id']); $product->setDiscount($row['discount']); return $product; } 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); } function getProducer(){ return $this->producerFirstName." ".$this->producerMainName; } function getSummaryLine(){ $base = "$this->title({$this->producerMainName},"; $base .= "{$this->producerFirstName})"; return $base; }}class CdProduct extends ShopProduct{ private $playLength; function __construct($title,$firstName,$mainName,$price,$playLength){ parent::__construct($title,$firstName,$mainName,$price);//继承父类的构造函数 $this->playLength = $playLength; } function getPlayLength(){ return $this->playLength; } function getSummaryLine(){ $base = parent::getSummaryLine(); $base .= ":playing time {$this->playLength}"; return $base; }}class BookProduct extends ShopProduct{ private $numPages = 0; function __construct($title,$firstName,$mainName,$price,$numPages){ parent::__construct($title,$firstName,$mainName,$price); $this->numPages = $numPages; } function getnumPages(){ return $this->numPages; } function getSummaryLine(){ $base = parent::getSummaryLine(); $base .= ":page count {$this->numPages}"; return $base; }}$dsn = "sqlite:C:/Users/Administrator/Desktop/shop.db";$pdo = new PDO($dsn,null,null);$pdo->setAttribute(PDO::ATTR_ERRMODE,PDO::ERRMODE_EXCEPTION);$obj = ShopProduct::getInstance(1,$pdo);echo $obj->getSummaryLine(); |
希望本文所述对大家PHP程序设计有所帮助。
