php结合curl实现多线程抓取

<?php
/*
curl 多线程抓取
*/
 /** 
   * curl 多线程 
   * 
   * @param array $array 并行网址 
   * @param int $timeout 超时时间
   * @return array 
   */ 
 function Curl_http($array,$timeout){
 $res = array();
 $mh = curl_multi_init();//创建多个curl语柄
 $startime = getmicrotime();
 foreach($array as $k=>$url){
  $conn[$k]=curl_init($url);

    curl_setopt($conn[$k], CURLOPT_TIMEOUT, $timeout);//设置超时时间
    curl_setopt($conn[$k], CURLOPT_USERAGENT, 'Mozilla/5.0 (compatible; MSIE 5.01; Windows NT 5.0)');
    curl_setopt($conn[$k], CURLOPT_MAXREDIRS, 7);//HTTp定向级别
    curl_setopt($conn[$k], CURLOPT_HEADER, 0);//这里不要header，加块效率
    curl_setopt($conn[$k], CURLOPT_FOLLOWLOCATION, 1); // 302 redirect
    curl_setopt($conn[$k],CURLOPT_RETURNTRANSFER,1);
    curl_multi_add_handle ($mh,$conn[$k]);
 }
 //防止死循环耗死cpu 这段是根据网上的写法
 do {
  $mrc = curl_multi_exec($mh,$active);//当无数据，active=true
 } while ($mrc == CURLM_CALL_MULTI_PERFORM);//当正在接受数据时
 while ($active and $mrc == CURLM_OK) {//当无数据时或请求暂停时，active=true
  if (curl_multi_select($mh) != -1) {
  do {
   $mrc = curl_multi_exec($mh, $active);
  } while ($mrc == CURLM_CALL_MULTI_PERFORM);
  }
 }

 foreach ($array as $k => $url) {
   curl_error($conn[$k]);
    $res[$k]=curl_multi_getcontent($conn[$k]);//获得返回信息
    $header[$k]=curl_getinfo($conn[$k]);//返回头信息
    curl_close($conn[$k]);//关闭语柄
    curl_multi_remove_handle($mh , $conn[$k]);  //释放资源 
 }

 curl_multi_close($mh);
 $endtime = getmicrotime();
 $diff_time = $endtime - $startime;

 return array('diff_time'=>$diff_time,
   'return'=>$res,
   'header'=>$header 
   );

 }
 //计算当前时间
 function getmicrotime() {
   list($usec, $sec) = explode(" ",microtime());
   return ((float)$usec + (float)$sec);
 }

 //测试一下，curl 三个网址
 $array = array(
  "http://www.weibo.com/",
  "http://www.renren.com/",
  "http://www.qq.com/"
  );
 $data = Curl_http($array,'10');//调用
 var_dump($data);//输出
//如果POST的数据大于1024字节，curl并不会直接就发起POST请求
//发送请求时，header中包含一个空的Expect。curl_setopt($ch, CURLOPT_HTTPHEADER, array("Expect:"));
?>

我们再来看几个例子

（1）下面这段代码是实现抓取多个URL，然后将抓取的URL的页面代码写入指定的文件

$urls = array(
'https://www.jb51.net/',
'http://www.google.com/',
'http://www.example.com/'
); // 设置要抓取的页面URL
$save_to='/test.txt'; // 把抓取的代码写入该文件
$st = fopen($save_to,"a");
$mh = curl_multi_init();
foreach ($urls as $i => $url) {
$conn[$i] = curl_init($url);
curl_setopt($conn[$i], CURLOPT_USERAGENT, "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0)");
curl_setopt($conn[$i], CURLOPT_HEADER ,0);
curl_setopt($conn[$i], CURLOPT_CONNECTTIMEOUT,60);
curl_setopt($conn[$i], CURLOPT_FILE,$st); // 将爬取的代码写入文件
curl_multi_add_handle ($mh,$conn[$i]);
} // 初始化
do {
curl_multi_exec($mh,$active);
} while ($active); // 执行
foreach ($urls as $i => $url) {
curl_multi_remove_handle($mh,$conn[$i]);
curl_close($conn[$i]);
} // 结束清理
curl_multi_close($mh);
fclose($st);

（2）下面这段代码和上面差不多意思，只不过这个地方是将获得的代码先放入变量，然后再将获取到的内容写入指定的文件

$urls = array(
'https://www.jb51.net/',
'http://www.google.com/',
'http://www.example.com/'
);
$save_to='/test.txt'; // 把抓取的代码写入该文件
$st = fopen($save_to,"a");
$mh = curl_multi_init();
foreach ($urls as $i => $url) {
$conn[$i] = curl_init($url);
curl_setopt($conn[$i], CURLOPT_USERAGENT, "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0)");
curl_setopt($conn[$i], CURLOPT_HEADER ,0);
curl_setopt($conn[$i], CURLOPT_CONNECTTIMEOUT,60);
curl_setopt($conn[$i],CURLOPT_RETURNTRANSFER,true); // 不将爬取代码写到浏览器，而是转化为字符串
curl_multi_add_handle ($mh,$conn[$i]);
}
do {
curl_multi_exec($mh,$active);
} while ($active);
foreach ($urls as $i => $url) {
$data = curl_multi_getcontent($conn[$i]); // 获得爬取的代码字符串
fwrite($st,$data); // 将字符串写入文件
} // 获得数据变量，并写入文件
foreach ($urls as $i => $url) {
curl_multi_remove_handle($mh,$conn[$i]);
curl_close($conn[$i]);
}
curl_multi_close($mh);
fclose($st);

（3）下面这段代码实现的是利用 PHP 的 Curl Functions 实现并发多线程下载文件

$urls=array(
 'https://www.jb51.net/5w.zip',
 'https://www.jb51.net/5w.zip',
 'https://www.jb51.net/5w.zip'
);
$save_to='./home/';
$mh=curl_multi_init();
foreach($urls as $i=>$url){
 $g=$save_to.basename($url);
 if(!is_file($g)){
   $conn[$i]=curl_init($url);
   $fp[$i]=fopen($g,"w");
   curl_setopt($conn[$i],CURLOPT_USERAGENT,"Mozilla/4.0(compatible; MSIE 7.0; Windows NT 6.0)");
   curl_setopt($conn[$i],CURLOPT_FILE,$fp[$i]);
   curl_setopt($conn[$i],CURLOPT_HEADER ,0);
   curl_setopt($conn[$i],CURLOPT_CONNECTTIMEOUT,60);
   curl_multi_add_handle($mh,$conn[$i]);
 }
}
do{
 $n=curl_multi_exec($mh,$active);
}while($active);
foreach($urls as $i=>$url){
 curl_multi_remove_handle($mh,$conn[$i]);
 curl_close($conn[$i]);
 fclose($fp[$i]);
}
curl_multi_close($mh);$urls=array(
 'https://www.jb51.net/5w.zip',
 'https://www.jb51.net/5w.zip',
 'https://www.jb51.net/5w.zip'
);
$save_to='./home/';
$mh=curl_multi_init();
foreach($urls as $i=>$url){
 $g=$save_to.basename($url);
 if(!is_file($g)){
   $conn[$i]=curl_init($url);
   $fp[$i]=fopen($g,"w");
   curl_setopt($conn[$i],CURLOPT_USERAGENT,"Mozilla/4.0(compatible; MSIE 7.0; Windows NT 6.0)");
   curl_setopt($conn[$i],CURLOPT_FILE,$fp[$i]);
   curl_setopt($conn[$i],CURLOPT_HEADER ,0);
   curl_setopt($conn[$i],CURLOPT_CONNECTTIMEOUT,60);
   curl_multi_add_handle($mh,$conn[$i]);
 }
}
do{
 $n=curl_multi_exec($mh,$active);
}while($active);
foreach($urls as $i=>$url){
 curl_multi_remove_handle($mh,$conn[$i]);
 curl_close($conn[$i]);
 fclose($fp[$i]);
}
curl_multi_close($mh);