使用方法：

$urls = array("http://baidu.com", "http://21andy.com", "http://google.com");
$mp = new MultiHttpRequest($urls);
$mp->start();

/*
 * Curl 多线程类
 * 使用方法：
 * ========================
$urls = array("http://baidu.com", "http://dzone.com", "http://google.com");
$mp = new MultiHttpRequest($urls);
$mp->start();
 * ========================
 */
class MultiHttpRequest {
  public $urls = array();
  public $curlopt_header = 1;
  public $method = "GET";
 
  function __construct($urls = false) {
    $this->urls = $urls;
  }
 
  function set_urls($urls) {
    $this->urls = $urls;
    return $this;
   }
 
   function is_return_header($b) {
     $this->curlopt_header = $b;
     return $this;
   }
 
   function set_method($m) {
     $this->medthod = strtoupper($m);
     return $this;
   }
 
   function start() {
     if(!is_array($this->urls) or count($this->urls) == 0){
      return false;
     }
     $curl = $text = array();
     $handle = curl_multi_init();
     foreach($this->urls as $k=>$v){
      $curl[$k] = $this->add_handle($handle, $v);
     }
 
     $this->exec_handle($handle);
     foreach($this->urls as $k=>$v){
       curl_multi_getcontent($curl[$k]);
       echo $curl[$k]."n";
       //$text[$k] = curl_multi_getcontent($curl[$k]);
       //echo $text[$k], "nn";
       curl_multi_remove_handle($handle, $curl[$k]);
     }
     curl_multi_close($handle);
   }
 
   private function add_handle($handle, $url) {
     $curl = curl_init();
     curl_setopt($curl, CURLOPT_URL, $url);
     curl_setopt($curl, CURLOPT_HEADER, $this->curlopt_header);
     curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);
     curl_multi_add_handle($handle, $curl);
     return $curl;
   }
 
   private function exec_handle($handle) {
     $flag = null;
     do {
      curl_multi_exec($handle, $flag);
     } while ($flag > 0);
   }
}