做过好多抓取别家网站内容的产品,习惯了使用方便快捷的file_get_contents函数,但是总是会遇到获取失败的问题,尽管按照手册中的例子设置了超时,可多数时候不会奏效:
$config[\'context\'] = stream_context_create(array(‘http\' => array(‘method\' => “GET”,
\'timeout\' => 5//这个超时时间不稳定,经常不奏效
)
));
这时候,看一下服务器的连接池,会发现一堆类似的错误,让你头疼万分:
file_get_contents(http://***): failed to open stream…
不得已,安装了curl库,写了一个函数替换:
<span style=\"color:#000000; font-weight:bold\">function</span> curl_file_get_contents<span style=\"color:#009900\">(</span><span style=\"color:#000088\">$durl</span><span style=\"color:#009900\">)</span><span style=\"color:#009900\">{</span>
<span style=\"color:#000088\">$ch</span> <span style=\"color:#339933\">=</span> <span style=\"color:#990000\">curl_init</span><span style=\"color:#009900\">(</span><span style=\"color:#009900\">)</span><span style=\"color:#339933\">;</span>
<span style=\"color:#990000\">curl_setopt</span><span style=\"color:#009900\">(</span><span style=\"color:#000088\">$ch</span><span style=\"color:#339933\">,</span> CURLOPT_URL<span style=\"color:#339933\">,</span> <span style=\"color:#000088\">$durl</span><span style=\"color:#009900\">)</span><span style=\"color:#339933\">;</span>
<span style=\"color:#990000\">curl_setopt</span><span style=\"color:#009900\">(</span><span style=\"color:#000088\">$ch</span><span style=\"color:#339933\">,</span> CURLOPT_TIMEOUT<span style=\"color:#339933\">,</span> <span style=\"color:#cc66cc\">5</span><span style=\"color:#009900\">)</span><span style=\"color:#339933\">;</span>
<span style=\"color:#990000\">curl_setopt</span><span style=\"color:#009900\">(</span><span style=\"color:#000088\">$ch</span><span style=\"color:#339933\">,</span> CURLOPT_USERAGENT<span style=\"color:#339933\">,</span> _USERAGENT_<span style=\"color:#009900\">)</span><span style=\"color:#339933\">;</span>
<span style=\"color:#990000\">curl_setopt</span><span style=\"color:#009900\">(</span><span style=\"color:#000088\">$ch</span><span style=\"color:#339933\">,</span> CURLOPT_REFERER<span style=\"color:#339933\">,</span>_REFERER_<span style=\"color:#009900\">)</span><span style=\"color:#339933\">;</span>
<span style=\"color:#990000\">curl_setopt</span><span style=\"color:#009900\">(</span><span style=\"color:#000088\">$ch</span><span style=\"color:#339933\">,</span> CURLOPT_RETURNTRANSFER<span style=\"color:#339933\">,</span> <span style=\"color:#cc66cc\">1</span><span style=\"color:#009900\">)</span><span style=\"color:#339933\">;</span>
<span style=\"color:#000088\">$r</span> <span style=\"color:#339933\">=</span> <span style=\"color:#990000\">curl_exec</span><span style=\"color:#009900\">(</span><span style=\"color:#000088\">$ch</span><span style=\"color:#009900\">)</span><span style=\"color:#339933\">;</span>
<span style=\"color:#990000\">curl_close</span><span style=\"color:#009900\">(</span><span style=\"color:#000088\">$ch</span><span style=\"color:#009900\">)</span><span style=\"color:#339933\">;</span>
<span style=\"color:#b1b100\">return</span> <span style=\"color:#000088\">$r</span><span style=\"color:#339933\">;</span>
<span style=\"color:#009900\">}</span>
如此,除了真正的网络问题外,没再出现任何问题。
这是别人做过的关于curl和file_get_contents的测试:
file_get_contents抓取google.com需用秒数:
2.31319094
2.30374217
2.21512604
3.30553889
2.30124092
curl使用的时间:
0.68719101
0.64675593
0.64326
0.81983113
0.63956594
差距很大吧?呵呵,从我使用的经验来说,这两个工具不只是速度有差异,稳定性也相差很大。建议对网络数据抓取稳定性要求比较高的朋友使用上面的curl_file_get_contents函数,不但稳定速度快,还能假冒浏览器欺骗目标地址哦!