php 高级特性,PHP对象、模式与实践之高级特性分析
本文實例講述了PHP面向對象程序設計高級特性。分享給大家供大家參考，具體如下：
高級特性
包括：
1.靜態方法和屬性(通過類而不是對象來訪問數據和功能)
2.抽象類和接口(設計，實現分離)
3.錯誤處理(異常)
4.Final類和方法(限制繼承)
5.攔截器(自動委托)
6.析構方法(對象銷毀前的清理工作)
7.克隆對象(創建對象的副本)
8.把對象解析成字符串
PS，學會從內存的角度看代碼。想象計算機的微觀世界。
靜態方法的小例子
class StaticExample{
static public $aNum = 10;
static public function sayHello(){
print "hello";
}
}
print StaticExample::$aNum."
";
StaticExample::sayHello();
tips:
1.靜態方法不能訪問類中的普通屬性，因為那些屬性屬于一個對象，但可以訪問靜態屬性。
2.我們不能再對象中調用靜態方法，因此不能再靜態方法中使用偽變量$this。
靜態方法的大例子
class 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);//繼承父類的構造函數
$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();
希望本文所述對大家PHP程序設計有所幫助。
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