PHP对象、模式与实践之高级特性分析
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
<?php
class 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
<?php
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);//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();
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希望本文所述对大家PHP程序设计有所帮助。