PHP对象、模式与实践之高级特性分析

 更新时间:2016年12月08日 08:46:23   转载 作者:牛逼的霍啸林  
这篇文章主要介绍了PHP对象、模式与实践之高级特性,结合实例形式分析了php面向对象程序设计中的静态属性和方法、抽象类、接口、拦截器、克隆对象等概念与简单实现方法,需要的朋友可以参考下

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();

更多关于PHP相关内容感兴趣的读者可查看本站专题:《php面向对象程序设计入门教程》、《PHP基本语法入门教程》、《PHP运算与运算符用法总结》、《PHP网络编程技巧总结》、《PHP数组(Array)操作技巧大全》、《php字符串(string)用法总结》、《php+mysql数据库操作入门教程》及《php常见数据库操作技巧汇总

希望本文所述对大家PHP程序设计有所帮助。

相关文章

最新评论