php让图片可以下载的代码_php技巧

让图片也能像附件一样的下载，不多说了。请看下面的程序！

// 文件目录 
define(‘DL_DIR', ‘temp/'); 
// 常见扩展名所对应的MIME类型 
$MIMETypes = array( 
‘ez' => ‘application/andrew-inset', 
‘hqx' => ‘application/mac-binhex40′, 
‘cpt' => ‘application/mac-compactpro', 
‘doc' => ‘application/msword', 
‘bin' => ‘application/octet-stream', 
‘dms' => ‘application/octet-stream', 
‘lha' => ‘application/octet-stream', 
‘lzh' => ‘application/octet-stream', 
‘exe' => ‘application/octet-stream', 
‘class' => ‘application/octet-stream', 
'so' => ‘application/octet-stream', 
‘dll' => ‘application/octet-stream', 
‘oda' => ‘application/oda', 
‘pdf' => ‘application/pdf', 
‘ai' => ‘application/postscrīpt', 
‘eps' => ‘application/postscrīpt', 
‘ps' => ‘application/postscrīpt', 
'smi' => ‘application/smil', 
'smil' => ‘application/smil', 
‘mif' => ‘application/vnd.mif', 
‘xls' => ‘application/vnd.ms-excel', 
‘ppt' => ‘application/vnd.ms-powerpoint', 
‘wbxml' => ‘application/vnd.wap.wbxml', 
‘wmlc' => ‘application/vnd.wap.wmlc', 
‘wmlsc' => ‘application/vnd.wap.wmlscrīptc', 
‘bcpio' => ‘application/x-bcpio', 
‘vcd' => ‘application/x-cdlink', 
‘pgn' => ‘application/x-chess-pgn', 
‘cpio' => ‘application/x-cpio', 
‘csh' => ‘application/x-csh', 
‘dcr' => ‘application/x-director', 
‘dir' => ‘application/x-director', 
‘dxr' => ‘application/x-director', 
‘dvi' => ‘application/x-dvi', 
'spl' => ‘application/x-futuresplash', 
‘gtar' => ‘application/x-gtar', 
‘hdf' => ‘application/x-hdf', 
‘js' => ‘application/x-javascrīpt', 
'skp' => ‘application/x-koan', 
'skd' => ‘application/x-koan', 
'skt' => ‘application/x-koan', 
'skm' => ‘application/x-koan', 
‘latex' => ‘application/x-latex', 
‘nc' => ‘application/x-netcdf', 
‘cdf' => ‘application/x-netcdf', 
'sh' => ‘application/x-sh', 
'shar' => ‘application/x-shar', 
'swf' => ‘application/x-shockwave-flash', 
'sit' => ‘application/x-stuffit', 
'sv4cpio' => ‘application/x-sv4cpio', 
'sv4crc' => ‘application/x-sv4crc', 
‘tar' => ‘application/x-tar', 
‘tcl' => ‘application/x-tcl', 
‘tex' => ‘application/x-tex', 
‘texinfo' => ‘application/x-texinfo', 
‘texi' => ‘application/x-texinfo', 
‘t' => ‘application/x-troff', 
‘tr' => ‘application/x-troff', 
‘roff' => ‘application/x-troff', 
‘man' => ‘application/x-troff-man', 
‘me' => ‘application/x-troff-me', 
‘ms' => ‘application/x-troff-ms', 
‘ustar' => ‘application/x-ustar', 
'src' => ‘application/x-wais-source', 
‘xhtml' => ‘application/xhtml+xml', 
‘xht' => ‘application/xhtml+xml', 
‘zip' => ‘application/zip', 
‘au' => ‘audio/basic', 
'snd' => ‘audio/basic', 
‘mid' => ‘audio/midi', 
‘midi' => ‘audio/midi', 
‘kar' => ‘audio/midi', 
‘mpga' => ‘audio/mpeg', 
‘mp2′ => ‘audio/mpeg', 
‘mp3′ => ‘audio/mpeg', 
‘aif' => ‘audio/x-aiff', 
‘aiff' => ‘audio/x-aiff', 
‘aifc' => ‘audio/x-aiff', 
‘m3u' => ‘audio/x-mpegurl', 
‘ram' => ‘audio/x-pn-realaudio', 
‘rm' => ‘audio/x-pn-realaudio', 
‘rpm' => ‘audio/x-pn-realaudio-plugin', 
‘ra' => ‘audio/x-realaudio', 
‘wav' => ‘audio/x-wav', 
‘pdb' => ‘chemical/x-pdb', 
‘xyz' => ‘chemical/x-xyz', 
‘bmp' => ‘image/bmp', 
‘gif' => ‘image/gif', 
‘ief' => ‘image/ief', 
‘jpeg' => ‘image/jpeg', 
‘jpg' => ‘image/jpeg', 
‘jpe' => ‘image/jpeg', 
‘png' => ‘image/png', 
‘tiff' => ‘image/tiff', 
‘tif' => ‘image/tiff', 
‘djvu' => ‘image/vnd.djvu', 
‘djv' => ‘image/vnd.djvu', 
‘wbmp' => ‘image/vnd.wap.wbmp', 
‘ras' => ‘image/x-cmu-raster', 
‘pnm' => ‘image/x-portable-anymap', 
‘pbm' => ‘image/x-portable-bitmap', 
‘pgm' => ‘image/x-portable-graymap', 
‘ppm' => ‘image/x-portable-pixmap', 
‘rgb' => ‘image/x-rgb', 
‘xbm' => ‘image/x-xbitmap', 
‘xpm' => ‘image/x-xpixmap', 
‘xwd' => ‘image/x-xwindowdump', 
‘igs' => ‘model/iges', 
‘iges' => ‘model/iges', 
‘msh' => ‘model/mesh', 
‘mesh' => ‘model/mesh', 
'silo' => ‘model/mesh', 
‘wrl' => ‘model/vrml', 
‘vrml' => ‘model/vrml', 
‘css' => ‘text/css', 
‘html' => ‘text/html', 
‘htm' => ‘text/html', 
‘asc' => ‘text/plain', 
‘txt' => ‘text/plain', 
‘rtx' => ‘text/richtext', 
‘rtf' => ‘text/rtf', 
'sgml' => ‘text/sgml', 
'sgm' => ‘text/sgml', 
‘tsv' => ‘text/tab-separated-values', 
‘wml' => ‘text/vnd.wap.wml', 
‘wmls' => ‘text/vnd.wap.wmlscrīpt', 
‘etx' => ‘text/x-setext', 
‘xsl' => ‘text/xml', 
‘xml' => ‘text/xml', 
‘mpeg' => ‘video/mpeg', 
‘mpg' => ‘video/mpeg', 
‘mpe' => ‘video/mpeg', 
‘qt' => ‘video/quicktime', 
‘mov' => ‘video/quicktime', 
‘mxu' => ‘video/vnd.mpegurl', 
‘avi' => ‘video/x-msvideo', 
‘movie' => ‘video/x-sgi-movie', 
‘ice' => ‘x-conference/x-cooltalk', 
); 
?>

复制代码 代码如下:

<?php 
// 安全性过滤 
$fileName = basename($_SERVER[&#39;QUERY_STRING&#39;]); 
$filePath = dirname(__FILE__) . ‘/&#39; . DL_DIR . $fileName; 
/* 
简述: DIRECTORY_SEPARATOR(目录界定符, 目录函数库预定义常量) 
来源: Directory 目录函数(PHP手册->函数参考->Directories节点) 
说明: windows系统下为反斜杠&#39;\&#39;, Linux系统下为&#39;/&#39;, 
windows下两个都正常用, linux就不知道了, 为了标准, 显得专业点, 嘿嘿. 
*/ 
$filePath = str_replace(array(‘/&#39;, ‘\\&#39;), DIRECTORY_SEPARATOR, $filePath); 
if(!is_file($filePath)) { 
exit(‘File: &#39; . $fileName . ‘ not exists!&#39;); 
} else { // 如果是一个有效的文件 
// 文件扩展名 
$fileExt = substr(strrchr($fileName, ‘.&#39;), 1); 
// 文件类型 
$fileType = $MIMETypes[$fileExt] ? $MIMETypes[$fileExt] : ‘application/octet-stream&#39;; 
// 是否是图片 
$isImage = False; 
/* 
简述: getimagesize(), 详见手册 
说明: 判定某个文件是否为图片的有效手段, 常用在文件上传验证 
*/ 
$imgInfo = @getimagesize($filePath); 
if ($imgInfo[2] && $imgInfo[&#39;bits&#39;]) { 
$isImage = True; 
} 
// 显示方式 
$attachment = $isImage ? ‘inline&#39; : ‘attachment&#39;; 
// 读取文件 
if (is_readable($filePath)) { 
/* 
简述: ob_end_clean() 清空并关闭输出缓冲, 详见手册 
说明: 关闭输出缓冲, 使文件片段内容读取至内存后即被送出, 减少资源消耗 
*/ 
ob_end_clean(); 
/* 
HTTP头信息: 指示客户机可以接收生存期不大于指定时间（秒）的响应 
*/ 
header(‘Cache-control: max-age=31536000′); 
/* 
HTTP头信息: 缓存文件过期时间(格林威治标准时) 
*/ 
header(‘Expires: &#39; . gmdate(‘D, d M Y H:i:s&#39;, time()+31536000) . ‘ GMT&#39;); 
/* 
HTTP头信息: 文件在服务期端最后被修改的时间 
Cache-control,Expires,Last-Modified 都是控制浏览器缓存的头信息 
在一些访问量巨大的门户, 合理的设置缓存能够避免过多的服务器请求, 一定程度下缓解服务器的压力 
*/ 
header(‘Last-Modified: &#39; . gmdate(‘D, d M Y H:i:s&#39; , filemtime($filePath) . ‘ GMT&#39;)); 
/* 
HTTP头信息: 文档的编码(Encode)方法, 因为附件请求的文件多样化, 改变编码方式有可能损坏文件, 故为none 
*/ 
header(‘Content-Encoding: none&#39;); 
/* 
HTTP头信息: 告诉浏览器当前请求的文件类型. 
1.始终指定为application/octet-stream, 就代表文件是二进制流, 始终提示下载. 
2.指定对应的类型, 如请求的是mp3文件, 对应的MIME类型是audio/mpeg, IE就会自动启动Windows Media Player进行播放. 
*/ 
header(‘Content-type: &#39; . $fileType); 
/* 
HTTP头信息: 如果为attachment, 则告诉浏览器, 在访问时弹出”文件下载”对话框, 
并指定保存时文件的默认名称(可以与服务器的文件名不同) 
如果要让浏览器直接显示内容, 则要指定为inline, 如图片, 文本 
*/ 
header(‘Content-Disposition: &#39; . $attachment . ‘; filename=&#39; . $fileName); 
/* 
HTTP头信息: 告诉浏览器文件长度 
(IE下载文件的时候不是有文件大小信息么?) 
*/ 
header(‘Content-Length: &#39; . filesize($filePath)); 
// 打开文件(二进制只读模式) 
$fp = fopen($filePath, ‘rb&#39;); 
// 输出文件 
fpassthru($fp); 
// 关闭文件 
fclose($fp); 
exit(); 
} else { 
exit(‘Read file failed!&#39;); 
} 
} 
?>

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