抓取 图片
最近要抓取智库百科中的词条，但是词条中的图片抓取出现了问题，这是其中一个图片链接。http://wiki.mbalib.com/w/images/2/22/%E6%B3%9B%E6%88%90%E6%9C%AC%E7%9A%84%E7%89%B9%E5%BE%81.jpg
无论是用file_get_contents，还是ob_start后readfile，还是用curl，还是snoopy，抓取下来的图片都是损坏的，抓下来的数据比原图小，但我看了一下这个站的图片貌似并没有设置防盗链或cookie验证之类的，求解决方法
回复讨论(解决方案)
他传送的图片数据是 gzip 压缩的，需要使用 gzdecode 函数解码（php5>=5.4.0 已添加进 gzip 扩展了
$url = 'http://wiki.mbalib.com/w/images/2/22/%E6%B3%9B%E6%88%90%E6%9C%AC%E7%9A%84%E7%89%B9%E5%BE%81.jpg';$s = file_get_contents($url);echo gzdecode($s);如果你的 php 版本还没有那么高，可以自己写代码。网上也可以搜索到。
给一个老外的
function gzdecode($data) { $len = strlen($data); if ($len < 18 || strcmp(substr($data,0,2),"\x1f\x8b")) { return $data; // 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 data; } // 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 < 8) { return false; // Invalid format } $extralen = unpack("v",substr($data,8,2)); $extralen = $extralen[1]; if ($len - $headerlen - 2 - $extralen < 8) { 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 < 8) { return false; // Invalid format } $filenamelen = strpos(substr($data,8+$extralen),chr(0)); if ($filenamelen === false || $len - $headerlen - $filenamelen - 1 < 8) { 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 < 8) { return false; // Invalid format } $commentlen = strpos(substr($data,8+$extralen+$filenamelen),chr(0)); if ($commentlen === false || $len - $headerlen - $commentlen - 1 < 8) { 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 < 8) { 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 < 1) { // 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; } 他传送的图片数据是 gzip 压缩的，需要使用 gzdecode 函数解码（php5>=5.4.0 已添加进 gzip 扩展了
$url = 'http://wiki.mbalib.com/w/images/2/22/%E6%B3%9B%E6%88%90%E6%9C%AC%E7%9A%84%E7%89%B9%E5%BE%81.jpg';$s = file_get_contents($url);echo gzdecode($s);如果你的 php 版本还没有那么高，可以自己写代码。网上也可以搜索到。
给一个老外的
function gzdecode($data) { $len = strlen($data); if ($len < 18 || strcmp(substr($data,0,2),"\x1f\x8b")) { return $data; // 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 data; } // 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 < 8) { return false; // Invalid format } $extralen = unpack("v",substr($data,8,2)); $extralen = $extralen[1]; if ($len - $headerlen - 2 - $extralen < 8) { 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 < 8) { return false; // Invalid format } $filenamelen = strpos(substr($data,8+$extralen),chr(0)); if ($filenamelen === false || $len - $headerlen - $filenamelen - 1 < 8) { 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 < 8) { return false; // Invalid format } $commentlen = strpos(substr($data,8+$extralen+$filenamelen),chr(0)); if ($commentlen === false || $len - $headerlen - $commentlen - 1 < 8) { 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 < 8) { 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 < 1) { // 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; } 非常感谢，长知识了
