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

1. //$file 文件路径
2. public function download_file($file){
3.         if(is_file($file)){
4.             $length = filesize($file);
5.             $type = mime_content_type($file);
6.             $showname =  ltrim(strrchr($file,'/'),'/');
7.             header("Content-Description: File Transfer");
8.             header('Content-type: ' . $type);
9.             header('Content-Length:' . $length);
10.             if (preg_match('/MSIE/', $_SERVER['HTTP_USER_AGENT'])) { //for IE
11.                 header('Content-Disposition: attachment; filename="' . rawurlencode($showname) . '"');
12.             } else {
13.                 header('Content-Disposition: attachment; filename="' . $showname . '"');
14.             }
15.             readfile($file);
16.         } else {
17.             $this->error('源文件不存在！');
18.         }
19.     }

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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。

1. public function force_download($filename)
2.     {
3.         if ($filename == ''){
4.             return FALSE;
5.         }
6.         if (FALSE === strpos($filename, '.')){
7.             return FALSE;
8.         }
9.         $x = explode('.', $filename);
10.         $extension = end($x);
11.         $mimes =$this->getMimes();
12. 
    
13.         // Set a default mime if we can't find it
14.         if ( ! isset($mimes[$extension])){
15.             $mime = 'application/octet-stream';
16.         }else{
17.             $mime = (is_array($mimes[$extension])) ? $mimes[$extension][0] : $mimes[$extension];
18.         }
19.         // Generate the server headers
20.         if (strpos($_SERVER['HTTP_USER_AGENT'], "MSIE") !== FALSE)
21.         {
22.             header('Content-Type: "'.$mime.'"');
23.             header('Content-Disposition: attachment; filename="'.$filename.'"');
24.             header('Expires: 0');
25.             header('Cache-Control: must-revalidate, post-check=0, pre-check=0');
26.             header("Content-Transfer-Encoding: binary");
27.             header('Pragma: public');
28.             header("Content-Length: ".filesize($filename));
29.         }
30.         else
31.         {
32.             header('Content-Type: "'.$mime.'"');
33.             header('Content-Disposition: attachment; filename="'.$filename.'"');
34.             header("Content-Transfer-Encoding: binary");
35.             header('Expires: 0');
36.             header('Pragma: no-cache');
37.             header("Content-Length: ".filesize($filename));
38.         }
39.         readfile($filename);
40.     }
41. private function getMimes(){
42.         return $mimes = array(    'hqx'    =>    'application/mac-binhex40',
43.             'cpt'    =>    'application/mac-compactpro',
44.             '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'),
45.             'bin'    =>    'application/macbinary',
46.             'dms'    =>    'application/octet-stream',
47.             'lha'    =>    'application/octet-stream',
48.             'lzh'    =>    'application/octet-stream',
49.             'exe'    =>    array('application/octet-stream', 'application/x-msdownload'),
50.             'class'    =>    'application/octet-stream',
51.             'psd'    =>    'application/x-photoshop',
52.             'so'    =>    'application/octet-stream',
53.             'sea'    =>    'application/octet-stream',
54.             'dll'    =>    'application/octet-stream',
55.             'oda'    =>    'application/oda',
56.             'pdf'    =>    array('application/pdf', 'application/x-download'),
57.             'ai'    =>    'application/postscript',
58.             'eps'    =>    'application/postscript',
59.             'ps'    =>    'application/postscript',
60.             'smi'    =>    'application/smil',
61.             'smil'    =>    'application/smil',
62.             'mif'    =>    'application/vnd.mif',
63.             'xls'    =>    array('application/excel', 'application/vnd.ms-excel', 'application/msexcel'),
64.             'ppt'    =>    array('application/powerpoint', 'application/vnd.ms-powerpoint'),
65.             'wbxml'    =>    'application/wbxml',
66.             'wmlc'    =>    'application/wmlc',
67.             'dcr'    =>    'application/x-director',
68.             'dir'    =>    'application/x-director',
69.             'dxr'    =>    'application/x-director',
70.             'dvi'    =>    'application/x-dvi',
71.             'gtar'    =>    'application/x-gtar',
72.             'gz'    =>    'application/x-gzip',
73.             'php'    =>    'application/x-httpd-php',
74.             'php4'    =>    'application/x-httpd-php',
75.             'php3'    =>    'application/x-httpd-php',
76.             'phtml'    =>    'application/x-httpd-php',
77.             'phps'    =>    'application/x-httpd-php-source',
78.             'js'    =>    'application/x-javascript',
79.             'swf'    =>    'application/x-shockwave-flash',
80.             'sit'    =>    'application/x-stuffit',
81.             'tar'    =>    'application/x-tar',
82.             'tgz'    =>    array('application/x-tar', 'application/x-gzip-compressed'),
83.             'xhtml'    =>    'application/xhtml+xml',
84.             'xht'    =>    'application/xhtml+xml',
85.             'zip'    =>  array('application/x-zip', 'application/zip', 'application/x-zip-compressed'),
86.             'mid'    =>    'audio/midi',
87.             'midi'    =>    'audio/midi',
88.             'mpga'    =>    '',
89.             'mp2'    =>    '',
90.             'mp3'    =>    array('', 'audio/mpg', '3', 'audio/mp3'),
91.             'aif'    =>    'audio/x-aiff',
92.             'aiff'    =>    'audio/x-aiff',
93.             'aifc'    =>    'audio/x-aiff',
94.             'ram'    =>    'audio/x-pn-realaudio',
95.             'rm'    =>    'audio/x-pn-realaudio',
96.             'rpm'    =>    'audio/x-pn-realaudio-plugin',
97.             'ra'    =>    'audio/x-realaudio',
98.             'rv'    =>    'video/vnd.rn-realvideo',
99.             'wav'    =>    array('audio/x-wav', 'audio/wave', 'audio/wav'),
100.             'bmp'    =>    array('image/bmp', 'image/x-windows-bmp'),
101.             'gif'    =>    'image/gif',
102.             'jpeg'    =>    array('image/jpeg', 'image/pjpeg'),
103.             'jpg'    =>    array('image/jpeg', 'image/pjpeg'),
104.             'jpe'    =>    array('image/jpeg', 'image/pjpeg'),
105.             'png'    =>    array('image/png',  'image/x-png'),
106.             'tiff'    =>    'image/tiff',
107.             'tif'    =>    'image/tiff',
108.             'css'    =>    'text/css',
109.             'html'    =>    'text/html',
110.             'htm'    =>    'text/html',
111.             'shtml'    =>    'text/html',
112.             'txt'    =>    'text/plain',
113.             'text'    =>    'text/plain',
114.             'log'    =>    array('text/plain', 'text/x-log'),
115.             'rtx'    =>    'text/richtext',
116.             'rtf'    =>    'text/rtf',
117.             'xml'    =>    'text/xml',
118.             'xsl'    =>    'text/xml',
119.             'mpeg'    =>    'video/mpeg',
120.             'mpg'    =>    'video/mpeg',
121.             'mpe'    =>    'video/mpeg',
122.             'qt'    =>    'video/quicktime',
123.             'mov'    =>    'video/quicktime',
124.             'avi'    =>    'video/x-msvideo',
125.             'movie'    =>    'video/x-sgi-movie',
126.             'doc'    =>    'application/msword',
127.             'docx'    =>    array('application/vnd.openxmlformats-officedocument.wordprocessingml.document', 'application/zip'),
128.             'xlsx'    =>    array('application/vnd.openxmlformats-officedocument.spreadsheetml.sheet', 'application/zip'),
129.             'word'    =>    array('application/msword', 'application/octet-stream'),
130.             'xl'    =>    'application/excel',
131.             'eml'    =>    'message/rfc822',
132.             'json' => array('application/json', 'text/json')
133.         );

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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。