时间:2021-07-01 10:21:17 帮助过:16人阅读
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();
以上就是本文的全部内容,希望对大家的学习有所帮助。
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