使用抽象類的簡單捲曲包裝方法？

Question

即時嘗試在抽象類有一個很好的做法方法，所以我創建了一個簡單的捲曲包裝類，但不幸的是它不工作。
抽象

<?php 
abstract class curl{ 
    private $url; 

    public function __construct($url){ 
     $this->url = $url ; 
    } 
    public function curl_grab_page() 
    { 
      $ch = curl_init(); 
      curl_setopt($ch, CURLOPT_RETURNTRANSFER, TRUE); 
      curl_setopt($ch, CURLOPT_URL, $this->url); 
      curl_setopt($ch, CURLOPT_HEADER, TRUE); 
      curl_setopt($ch, CURLOPT_USERAGENT, $_SERVER['HTTP_USER_AGENT']); 
      curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, FALSE); 
      curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, FALSE); 
      curl_setopt($ch, CURLOPT_FOLLOWLOCATION, TRUE); 
      ob_start(); // prevent any output 
      return curl_exec ($ch); // execute the curl command 
      ob_end_clean(); // stop preventing output 
      curl_close ($ch); 
    } 
    public abstract function getHTML(); 

} 
?> 

孩子

<?php 
class google extends curl{ 
    private $url; 
    function __construct($url) { 
     parent::__construct($url); 
    } 
    function curl_grab_page(){ 
     parent::curl_grab_page(); 
    } 
    function getHTML(){ 
     return $this->curl_grab_page(); 
    } 
} 

，這是我在頭版怎麼稱呼。

<?php 
include 'classes/class.curl.php'; 
include 'classes/class.google.php'; 
$google = new google('http://www.google.com/'); 
echo $google->getHTML(); 
?> 

它沒有打印出任何東西。
我單獨審判的功能和它去細

Answer 1

看起來你是不是調用返回之前本地化輸出緩衝區的結果，試試這個：

public function curl_grab_page() 
{ 
     $ch = curl_init(); 
     curl_setopt($ch, CURLOPT_RETURNTRANSFER, TRUE); 
     curl_setopt($ch, CURLOPT_URL, $this->url); 
     curl_setopt($ch, CURLOPT_HEADER, TRUE); 
     curl_setopt($ch, CURLOPT_USERAGENT, $_SERVER['HTTP_USER_AGENT']); 
     curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, FALSE); 
     curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, FALSE); 
     curl_setopt($ch, CURLOPT_FOLLOWLOCATION, TRUE); 

     // Don't need any output buffering b/c you set CURLOPT_RETURNTRANSFER to true, which means the results will be returned via curl_exec 
     //ob_start(); // prevent any output 
     //return curl_exec ($ch); // execute the curl command 
     //ob_end_clean(); // stop preventing output 

     $contents = curl_exec($ch); 

     curl_close ($ch); 

     return $contents; 
} 

而子類：

<?php 
class google extends curl{ 
    // Don't need this, if you set the parent's scope to protected which means child class has access 
    // private $url; 

    function __construct($url) { 
     parent::__construct($url); 
    } 

    // Don't really need this method unless you plan on doing some custom logic   
    function curl_grab_page(){ 

     // If you keep this method I added a return here so we can get the results of the call 
     return parent::curl_grab_page(); 
    } 

    function getHTML(){ 
     return $this->curl_grab_page(); 
    } 
}