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详解PHP内置访问资源的超时时间 time_out file_get_contents read_file

Jun 13, 2016 am 11:51 AM
file get out php read time built-in I Ask a question time of access Detailed explanation resource time out

提问
我循环用file_get_contents抓取一堆url,但总是会在不到第100个URL的时候停下,提示我:“Warning: file_get_contents(URL) [function.file-get-
contents]: failed to open stream: HTTP request failed! HTTP/1.0 500 Read timed out
in D:\website\extra.php on line 65”
我在程序的开始已经有set_time_limit(0);了啊,那上面的错误会是因为什么呢?
回答
set_time_limit只是设置你的PHP程序的超时时间,而不是file_get_contents函数读取URL的超时时间。
从警告信息来看,是被抓取的网页出现了服务器500错误,可能是他的程序出现超时了。
如果想改变file_get_contents的超时时间,可以用resource $context的timeout参数:

复制代码 代码如下:


$opts = array(
'http'=>array(
    'method'=>"GET",
    'timeout'=>60,
   )
);
$context = stream_context_create($opts);
$html =file_get_contents('http://www.example.com', false, $context);
fpassthru($fp);


这样readfile函数的超时时间就设置成了10秒,如果你够细心的话,还会发现数组中还有一些其他的配置,第一维中的http是指定使用的网络协议,二维中的method批的是http的请求方法get,post,head等,timeout就是超时时间了。我想很多人会使用php内置的file_get_contents函数来下载网页,因为这个函数使用起来够简单。很多人也都很简单的使用它,只要传递一个链接它就可以自动的发送get请求,并将网页内容下载下来。如果比较复杂的情况,比如使用POST请求,使用代理下载,定义User-Agent等等,这时很多人就会认为这个函数做不了这样的事情,就会选择其他方式,如curl,来实现。实际上,这些事情file_get_contents也可以做到,
就是通过它的第三个参数,设置http请求的context
支持的设置和使用方式见官方说明:http://www.php.net/manual/en/context.http.php
附:目前我知道的支持context参数的php内置函数有file_get_contents,file_put_contents,readfile,file,fopen,copy(估计这一类的函数都支持吧,待确认)。

复制代码 代码如下:


function Post($url, $post = null)
{
$context = array();
if (is_array($post))
{
ksort($post);
$context['http'] = array
(
'timeout'=>60,
'method' => 'POST',
'content' => http_build_query($post, '', '&'),
);
}
return file_get_contents($url, false, stream_context_create($context));
}
$data = array
(
'name' => 'test',
'email' => 'test@gmail.com',
'submit' => 'submit',
);
echo Post('http://www.yifu.info', $data);


OK , 上面函数完美了,既解决了超时控制又解决了Post传值。再配合康盛的改良版RC4加密解密算法,做一个安全性很高的webservice就简单多了。
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