PHP实现文件下载

醉菜鸟 2021-12-10 09:00:53

class Download
{
    // 文件路径
    public $filepath;
    // 错误信息
    public $error;

    // 下载名称
    public $downName;
    private $isAttachment = false;

    private $_lang = array(
        'error' => '错误',
        'args_empty' => '参数错误。',
        'file_not_exists' => '文件不存在!',
        'file_not_readable' => '文件不可读!',
    );

    private $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',
        'wma' => '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',
        'wmv' => 'application/x-mplayer2',
        'ice' => 'x-conference/x-cooltalk',
    );
    
    public function init($filepath='', $down_name=''): bool
    {
        if($filepath == '' AND !$this->filepath)
        {
            $this->error = $this->_lang['error'] . ':' . $this->_lang['args_empty'];
            return false;
        }
        if($filepath == '') $filepath = $this->filepath;
        if(!file_exists($filepath))
        {
            $this->error = $this->_lang['error'] . ':' . $this->_lang['file_not_exists'];
            return false;
        }
        if($down_name == '' AND !$this->downName) $down_name = $filepath;
        if($down_name == '') $down_name = $this->down_name;
        // 文件扩展名
        $fileExt = substr(strrchr($filepath, '.'), 1);
        // 文件类型
        $fileType = $this->MIMETypes[$fileExt] ? $this->MIMETypes[$fileExt] : 'application/octet-stream';
        // 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['bits'])
        {
            $fileType = $imgInfo['mime'];       // 支持不标准扩展名
            $isImage = True;
        }
        // 显示方式
        if($this->isAttachment)
        {
            $attachment = 'attachment';     // 指定弹出下载对话框
        }
        else
        {
            $attachment = $isImage ? 'inline' : 'attachment';
        }
        // 读取文件
        if (is_readable($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: ' . gmdate('D, d M Y H:i:s', time()+31536000) . ' GMT');
            /*
            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: ' . gmdate('D, d M Y H:i:s' , filemtime($filepath) . ' GMT'));
            /*
            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');
            /*
            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: ' . $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: ' . $attachment . '; filename=' . $down_name);
            /*
            HTTP头信息: 告诉浏览器文件长度
            (IE下载文件的时候不是有文件大小信息么?)
            */
            header('Content-Length: ' . filesize($filepath));
            // 打开文件(二进制只读模式)
            $fp = fopen($filepath, 'rb');
            // 输出文件
            fpassthru($fp);
            // 关闭文件
            fclose($fp);
            return true;
        }
        else
        {
            $this->error = $this->_lang['error'] . ':' . $this->_lang['file_not_readable'];
            return false;
        }
    }
}
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