有时候我们会在开发中，经常会遇到有URL 301或 302重定向的情况，这时候我们可能需要获取重定向之后的url，下面我们介绍一下几种获取重定向url的方法：
1、用get_headers函数
php自带的get_headers函数可以获取服务器响应一个HTTP请求所发送的所有标头，我们可以尝试用该函数实现。
function get_redirect_url($url){$header = get_headers($url, 1);if (strpos($header[0], ’301′) !== false || strpos($header[0], ’302′) !== false) {if(is_array($header['Location'])) {return $header['Location'][count($header['Location'])-1];}else{return $header['Location'];}}else {return $url;}}
2、使用fsockopen()内置函数
function get_redirect_url($url){$redirect_url = false;$url_parts = @parse_url($url);if (!$url_parts) return false;if (!isset($url_parts['host'])) return false;if (!isset($url_parts['path'])) $url_parts['path'] = ‘/’;$sock = fsockopen($url_parts['host'], (isset($url_parts['port']) ? (int)$url_parts['port'] : 80), $errno, $errstr, 30);if (!$sock) return false;$request = “HEAD ” . $url_parts['path'] . (isset($url_parts['query']) ? ‘?’.$url_parts['query'] : ”) . ” HTTP/1.1\r\n”;$request .= ‘Host: ‘ . $url_parts['host'] . “\r\n”;$request .= “Connection: Close\r\n\r\n”;fwrite($sock, $request);$response = ”;while(!feof($sock)) $response .= fread($sock, 8192);fclose($sock);if (preg_match(‘/^Location: (.+?)$/m’, $response, $matches)){return trim($matches[1]);} else {return false;}}
3、使用cURL函数
function get_redirect_url($url, $referer=”, $timeout = 10) {$redirect_url = false;$ch = curl_init();curl_setopt($ch, CURLOPT_URL, $url);curl_setopt($ch, CURLOPT_HEADER, TRUE);curl_setopt($ch, CURLOPT_NOBODY, TRUE);//不返回请求体内容curl_setopt($ch, CURLOPT_FOLLOWLOCATION, TRUE);//允许请求的链接跳转curl_setopt($ch, CURLOPT_RETURNTRANSFER, TRUE);curl_setopt($ch, CURLOPT_TIMEOUT, $timeout);curl_setopt($ch, CURLOPT_HTTPHEADER, array(‘Accept: */*’,‘User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1)’,‘Connection: Keep-Alive’));if ($referer) {curl_setopt($ch, CURLOPT_REFERER, $referer);//设置referer}$content = curl_exec($ch);if(!curl_errno($ch)) {$redirect_url = curl_getinfo($ch, CURLINFO_EFFECTIVE_URL);//获取最终请求的url地址}return $redirect_url;}
哪个方法的效果更高一些，可以自行测试一下。
from：/zimuxin/article/details/52228917
