<?php class Http_MultiRequest {     //要并行抓取的url 列表     private $urls = array();     //curl 的选项     private $options;     //构造函数     function __construct($options = array())     {         $this->setOptions($options);     }     //设置url 列表     function setUrls($urls)     {         $this->urls = $urls;         return $this;     }     //设置选项     function setOptions($options)     {         $options[CURLOPT_RETURNTRANSFER] = 1;         if (isset($options['HTTP_POST']))         {             curl_setopt($ch, CURLOPT_POST, 1);             curl_setopt($ch, CURLOPT_POSTFIELDS, $options['HTTP_POST']);             unset($options['HTTP_POST']);         }         if (!isset($options[CURLOPT_USERAGENT]))         {             $options[CURLOPT_USERAGENT] = 'Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1;)';         }         if (!isset($options[CURLOPT_FOLLOWLOCATION]))         {             $options[CURLOPT_FOLLOWLOCATION] = 1;         }         if (!isset($options[CURLOPT_HEADER]))         {             $options[CURLOPT_HEADER] = 0;         }         $this->options = $options;     }     //并行抓取所有的内容     function exec()     {         if(empty($this->urls) || !is_array($this->urls))         {             return false;         }         $curl = $data = array();         $mh = curl_multi_init();         foreach($this->urls as $k => $v)         {             $curl[$k] = $this->addHandle($mh, $v);         }         $this->execMulitHandle($mh);         foreach($this->urls as $k => $v)         {             $data[$k] = curl_multi_getcontent($curl[$k]);             curl_multi_remove_handle($mh, $curl[$k]);         }         curl_multi_close($mh);         return $data;     }     //只抓取一个网页的内容。     function execOne($url)     {         if (empty($url)) {             return false;         }         $ch = curl_init($url);         $this->setOneOption($ch);         $content = curl_exec($ch);         curl_close($ch);         return $content;     }     //内部函数，设置某个handle 的选项     private function setOneOption($ch)     {         curl_setopt_array($ch, $this->options);     }     //添加一个新的并行抓取 handle     private function addHandle($mh, $url)     {         $ch = curl_init($url);         $this->setOneOption($ch);         curl_multi_add_handle($mh, $ch);         return $ch;     }     //并行执行(这样的写法是一个常见的错误，我这里还是采用这样的写法，这个写法     //下载一个小文件都可能导致cup占用100%, 并且，这个循环会运行10万次以上     //这是一个典型的不懂原理产生的错误。这个错误在PHP官方的文档上都相当的常见。）     private function execMulitHandle($mh)     {         $running = null;         do {             curl_multi_exec($mh, $running);         } while ($running > 0);     } } /*下面是上面的类的一个测试的例子：*/ $urls = array("http://baidu.com", "http://baidu.com", "http://baidu.com", "http://baidu.com", "http://baidu.com", "http://baidu.com", "http://www.google.com", "http://www.sina.com.cn", ); $m = new Http_MultiRequest(); $t = microtime(true); $m->setUrls($urls); //parallel fetch（并行抓取）: $data = $m->exec(); $parallel_time = microtime(true) - $t; echo $parallel_time . "\n"; $t = microtime(true); //serial fetch（串行抓取）: foreach ($urls as $url) {     $data[] = $m->execOne($url); } $serial_time = microtime(true) - $t; echo $serial_time . "\n";