php利用curl实现多线程类的示例

<?php 
class curl_multi{ 
    private $url_list=array(); 
    private $curl_setopt=array( 
        'CURLOPT_RETURNTRANSFER' => 1,//结果返回给变量 
        'CURLOPT_HEADER' => 0,//是否需要返回HTTP头 
        'CURLOPT_NOBODY' => 0,//是否需要返回的内容 
        'CURLOPT_FOLLOWLOCATION' => 0,//自动跟踪 
        'CURLOPT_TIMEOUT' => 6//超时时间(s) 
    ); 
    function construct($seconds=30){ 
        set_time_limit($seconds); 
    } 
    /* 
     * 设置网址 
     * @list 数组 
     */ 
    public function setUrlList($list=array()){ 
        $this->url_list=$list; 
    } 
    /* 
     * 设置参数 
     * @cutPot array 
     */ 
    public function setOpt($cutPot){ 
        $this->curl_setopt=$cutPot+$this->curl_setopt; 
    } 
    /* 
     * 执行 
     * @return array 
     */ 
    public function execute(){ 
        $mh=curl_multi_init(); 
        foreach($this->url_list as $i=>$url){ 
            $conn[$i]=curl_init($url); 
            foreach($this->curl_setopt as $key => $val){ 
                curl_setopt($conn[$i],preg_replace('/(CURLOPT_\w{1,})/ie','$0',$key),$val); 
            } 
            curl_multi_add_handle($mh,$conn[$i]); 
        } 
        $active=false; 
        do{ 
            $mrc=curl_multi_exec($mh,$active); 
        }while($mrc == CURLM_CALL_MULTI_PERFORM); 
 
        while($active and $mrc == CURLM_OK){ 
            if(curl_multi_select($mh) != -1){ 
                do{ 
                    $mrc=curl_multi_exec($mh,$active); 
                }while($mrc == CURLM_CALL_MULTI_PERFORM); 
            } 
        } 
        $res=array(); 
        foreach($this->url_list as $i => $url){ 
            $res[$i]=curl_multi_getcontent($conn[$i]); 
            curl_close($conn[$i]); 
            curl_multi_remove_handle($mh,$conn[$i]);//释放资源   
        } 
        curl_multi_close($mh); 
        return $res; 
    } 
}

$curl_mul=new curl_multi(); 
$curl_mul->setUrlList(array(' 
'http://www.baidu.com/img/baidu_sylogo1.gif')); 
$a=$curl_mul->execute(); 
$i=1; 
foreach($a as $v){ 
    $filename=$i.'.gif'; 
    $fp2=@fopen($filename,'a'); 
    fwrite($fp2,$v); 
    fclose($fp2); 
    $i++; 
}