下载文件总结

生成 HTTP 头强制下载数据到客户端，这在实现文件下载时很有用。

首先感谢@yangweijie的作品，在此基础上衍生出不需要开启php_fileinfo.dll扩展的方法。
方法一：开启扩展情况下

//$file 文件路径
public function download_file($file){
if(is_file($file)){
$length = filesize($file);
$type = mime_content_type($file);
$showname = ltrim(strrchr($file,'/'),'/');
header("Content-Description: File Transfer");
header('Content-type: ' . $type);
header('Content-Length:' . $length);
if (preg_match('/MSIE/', $_SERVER['HTTP_USER_AGENT'])) { //for IE
header('Content-Disposition: attachment; filename="' . rawurlencode($showname) . '"');
} else {
header('Content-Disposition: attachment; filename="' . $showname . '"');
}
readfile($file);
} else {
$this->error('源文件不存在！');
}
}

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方法二，如果没有开启php_fileinfo.dll，谁让咱是没有服务器权限的程序员呢，又不能让人家看不起，唉！可能你会懂。

public function force_download($filename)
{
if ($filename == ''){
return FALSE;
}
if (FALSE === strpos($filename, '.')){
return FALSE;
}
$x = explode('.', $filename);
$extension = end($x);
$mimes =$this->getMimes();
// Set a default mime if we can't find it
if ( ! isset($mimes[$extension])){
$mime = 'application/octet-stream';
}else{
$mime = (is_array($mimes[$extension])) ? $mimes[$extension][0] : $mimes[$extension];
}
// Generate the server headers
if (strpos($_SERVER['HTTP_USER_AGENT'], "MSIE") !== FALSE)
{
header('Content-Type: "'.$mime.'"');
header('Content-Disposition: attachment; filename="'.$filename.'"');
header('Expires: 0');
header('Cache-Control: must-revalidate, post-check=0, pre-check=0');
header("Content-Transfer-Encoding: binary");
header('Pragma: public');
header("Content-Length: ".filesize($filename));
}
else
{
header('Content-Type: "'.$mime.'"');
header('Content-Disposition: attachment; filename="'.$filename.'"');
header("Content-Transfer-Encoding: binary");
header('Expires: 0');
header('Pragma: no-cache');
header("Content-Length: ".filesize($filename));
}
readfile($filename);
}
private function getMimes(){
return $mimes = array( 'hqx' => 'application/mac-binhex40',
'cpt' => 'application/mac-compactpro',
'csv' => array('text/x-comma-separated-values', 'text/comma-separated-values', 'application/octet-stream', 'application/vnd.ms-excel', 'application/x-csv', 'text/x-csv', 'text/csv', 'application/csv', 'application/excel', 'application/vnd.msexcel'),
'bin' => 'application/macbinary',
'dms' => 'application/octet-stream',
'lha' => 'application/octet-stream',
'lzh' => 'application/octet-stream',
'exe' => array('application/octet-stream', 'application/x-msdownload'),
'class' => 'application/octet-stream',
'psd' => 'application/x-photoshop',
'so' => 'application/octet-stream',
'sea' => 'application/octet-stream',
'dll' => 'application/octet-stream',
'oda' => 'application/oda',
'pdf' => array('application/pdf', 'application/x-download'),
'ai' => 'application/postscript',
'eps' => 'application/postscript',
'ps' => 'application/postscript',
'smi' => 'application/smil',
'smil' => 'application/smil',
'mif' => 'application/vnd.mif',
'xls' => array('application/excel', 'application/vnd.ms-excel', 'application/msexcel'),
'ppt' => array('application/powerpoint', 'application/vnd.ms-powerpoint'),
'wbxml' => 'application/wbxml',
'wmlc' => 'application/wmlc',
'dcr' => 'application/x-director',
'dir' => 'application/x-director',
'dxr' => 'application/x-director',
'dvi' => 'application/x-dvi',
'gtar' => 'application/x-gtar',
'gz' => 'application/x-gzip',
'php' => 'application/x-httpd-php',
'php4' => 'application/x-httpd-php',
'php3' => 'application/x-httpd-php',
'phtml' => 'application/x-httpd-php',
'phps' => 'application/x-httpd-php-source',
'js' => 'application/x-javascript',
'swf' => 'application/x-shockwave-flash',
'sit' => 'application/x-stuffit',
'tar' => 'application/x-tar',
'tgz' => array('application/x-tar', 'application/x-gzip-compressed'),
'xhtml' => 'application/xhtml+xml',
'xht' => 'application/xhtml+xml',
'zip' => array('application/x-zip', 'application/zip', 'application/x-zip-compressed'),
'mid' => 'audio/midi',
'midi' => 'audio/midi',
'mpga' => '',
'mp2' => '',
'mp3' => array('', 'audio/mpg', '3', 'audio/mp3'),
'aif' => 'audio/x-aiff',
'aiff' => 'audio/x-aiff',
'aifc' => 'audio/x-aiff',
'ram' => 'audio/x-pn-realaudio',
'rm' => 'audio/x-pn-realaudio',
'rpm' => 'audio/x-pn-realaudio-plugin',
'ra' => 'audio/x-realaudio',
'rv' => 'video/vnd.rn-realvideo',
'wav' => array('audio/x-wav', 'audio/wave', 'audio/wav'),
'bmp' => array('image/bmp', 'image/x-windows-bmp'),
'gif' => 'image/gif',
'jpeg' => array('image/jpeg', 'image/pjpeg'),
'jpg' => array('image/jpeg', 'image/pjpeg'),
'jpe' => array('image/jpeg', 'image/pjpeg'),
'png' => array('image/png', 'image/x-png'),
'tiff' => 'image/tiff',
'tif' => 'image/tiff',
'css' => 'text/css',
'html' => 'text/html',
'htm' => 'text/html',
'shtml' => 'text/html',
'txt' => 'text/plain',
'text' => 'text/plain',
'log' => array('text/plain', 'text/x-log'),
'rtx' => 'text/richtext',
'rtf' => 'text/rtf',
'xml' => 'text/xml',
'xsl' => 'text/xml',
'mpeg' => 'video/mpeg',
'mpg' => 'video/mpeg',
'mpe' => 'video/mpeg',
'qt' => 'video/quicktime',
'mov' => 'video/quicktime',
'avi' => 'video/x-msvideo',
'movie' => 'video/x-sgi-movie',
'doc' => 'application/msword',
'docx' => array('application/vnd.openxmlformats-officedocument.wordprocessingml.document', 'application/zip'),
'xlsx' => array('application/vnd.openxmlformats-officedocument.spreadsheetml.sheet', 'application/zip'),
'word' => array('application/msword', 'application/octet-stream'),
'xl' => 'application/excel',
'eml' => 'message/rfc822',
'json' => array('application/json', 'text/json')
);

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看到这里估计大家都懂了，就是由后缀去匹配文件类型。实现mime_content_type的功能。