php file_get_contents抓取Gzip网页乱码的三种解决方法_php实例

把抓取到的内容转下编码即可($content=iconv("GBK", "UTF-8//IGNORE", $content);)，我们这里讨论的是如何抓取开了Gzip的页面。怎么判断呢？获取的头部当中有Content-Encoding: gzip说明内容是GZIP压缩的。用FireBug看一下就知道页面开了gzip没有。下面是用firebug查看我的博客的头信息，Gzip是开了的。

请求头信息原始头信息
Accept text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Encoding gzip, deflate
Accept-Language zh-cn,zh;q=0.8,en-us;q=0.5,en;q=0.3
Connection keep-alive
Cookie __utma=225240837.787252530.1317310581.1335406161.1335411401.1537; __utmz=225240837.1326850415.887.3.utmcsr=google|utmccn=(organic)|utmcmd=organic|utmctr=%E4%BB%BB%E4%BD%95%E9%A1%B9%E7%9B%AE%E9%83%BD%E4%B8%8D%E4%BC%9A%E9%82%A3%E4%B9%88%E7%AE%80%E5%8D%95%20site%3Awww.nowamagic.net; PHPSESSID=888mj4425p8s0m7s0frre3ovc7; __utmc=225240837; __utmb=225240837.1.10.1335411401
Host www.nowamagic.net
User-Agent Mozilla/5.0 (Windows NT 5.1; rv:12.0) Gecko/20100101 Firefox/12.0

下面介绍一些解决方案：

1. 使用自带的zlib库
如果服务器已经装了zlib库，用下面的代码可以轻易解决乱码问题。

$data = file_get_contents("compress.zlib://".$url);

2. 使用CURL代替file_get_contents

function curl_get($url, $gzip=false){
$curl = curl_init($url);
curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($curl, CURLOPT_CONNECTTIMEOUT, 10);
if($gzip) curl_setopt($curl, CURLOPT_ENCODING, "gzip"); // 关键在这里
$content = curl_exec($curl);
curl_close($curl);
return $content;
}

3. 使用gzip解压函数

function gzdecode($data) {
$len = strlen($data);
if ($len return null; // Not GZIP format (See RFC 1952)
}
$method = ord(substr($data,2,1)); // Compression method
$flags = ord(substr($data,3,1)); // Flags
if ($flags & 31 != $flags) {
// Reserved bits are set -- NOT ALLOWED by RFC 1952
return null;
}
// NOTE: $mtime may be negative (PHP integer limitations)
$mtime = unpack("V", substr($data,4,4));
$mtime = $mtime[1];
$xfl = substr($data,8,1);
$os = substr($data,8,1);
$headerlen = 10;
$extralen = 0;
$extra = "";
if ($flags & 4) {
// 2-byte length prefixed EXTRA data in header
if ($len - $headerlen - 2 return false; // Invalid format
}
$extralen = unpack("v",substr($data,8,2));
$extralen = $extralen[1];
if ($len - $headerlen - 2 - $extralen return false; // Invalid format
}
$extra = substr($data,10,$extralen);
$headerlen += 2 + $extralen;
}

$filenamelen = 0;
$filename = "";
if ($flags & 8) {
// C-style string file NAME data in header
if ($len - $headerlen - 1 return false; // Invalid format
}
$filenamelen = strpos(substr($data,8+$extralen),chr(0));
if ($filenamelen === false || $len - $headerlen - $filenamelen - 1 return false; // Invalid format
}
$filename = substr($data,$headerlen,$filenamelen);
$headerlen += $filenamelen + 1;
}

$commentlen = 0;
$comment = "";
if ($flags & 16) {
// C-style string COMMENT data in header
if ($len - $headerlen - 1 return false; // Invalid format
}
$commentlen = strpos(substr($data,8+$extralen+$filenamelen),chr(0));
if ($commentlen === false || $len - $headerlen - $commentlen - 1 return false; // Invalid header format
}
$comment = substr($data,$headerlen,$commentlen);
$headerlen += $commentlen + 1;
}

$headercrc = "";
if ($flags & 1) {
// 2-bytes (lowest order) of CRC32 on header present
if ($len - $headerlen - 2 return false; // Invalid format
}
$calccrc = crc32(substr($data,0,$headerlen)) & 0xffff;
$headercrc = unpack("v", substr($data,$headerlen,2));
$headercrc = $headercrc[1];
if ($headercrc != $calccrc) {
return false; // Bad header CRC
}
$headerlen += 2;
}

// GZIP FOOTER - These be negative due to PHP's limitations
$datacrc = unpack("V",substr($data,-8,4));
$datacrc = $datacrc[1];
$isize = unpack("V",substr($data,-4));
$isize = $isize[1];

// Perform the decompression:
$bodylen = $len-$headerlen-8;
if ($bodylen // This should never happen - IMPLEMENTATION BUG!
return null;
}
$body = substr($data,$headerlen,$bodylen);
$data = "";
if ($bodylen > 0) {
switch ($method) {
case 8:
// Currently the only supported compression method:
$data = gzinflate($body);
break;
default:
// Unknown compression method
return false;
}
} else {
// I'm not sure if zero-byte body content is allowed.
// Allow it for now... Do nothing...
}

// Verifiy decompressed size and CRC32:
// NOTE: This may fail with large data sizes depending on how
// PHP's integer limitations affect strlen() since $isize
// may be negative for large sizes.
if ($isize != strlen($data) || crc32($data) != $datacrc) {
// Bad format! Length or CRC doesn't match!
return false;
}
return $data;
}

使用：

$html=file_get_contents('http://www.jb51.net/');
$html=gzdecode($html);

就介绍这三个方法，应该能解决大部分gzip引起的抓取乱码问题了。