= $lastmodified)  
025     {  
026         header(http/1.1 304 not modified);  
027         return true;  
028     }  
029     
030     if (isset($_server['http_if_unmodified_since']) && strtotime($_server['http_if_unmodified_since'])
031     {  
032         header(http/1.1 304 not modified);  
033         return true;  
034     }  
035     
036     if (isset($_server['http_if_none_match']) &&  $_server['http_if_none_match'] == $etag)  
037     {  
038         header(http/1.1 304 not modified);  
039         return true;  
040     }  
041     
042     if ($fancyname == '')  
043     {  
044         $fancyname = basename($filename);  
045     }  
046     
047     if ($contenttype == '')  
048     {  
049         $contenttype = 'application/octet-stream';  
050     }  
051     
052     $filesize = $filestat['size'];  
053     
054     $contentlength = $filesize;  
055     $ispartial = false;  
056     
057     if (isset($_server['http_range']))  
058     {  
059         if (preg_match('/^bytes=(d*)-(d*)$/', $_server['http_range'], $matches))  
060         {  
061             $startpos = $matches[1];  
062             $endpos = $matches[2];  
063     
064             if ($startpos == '' && $endpos == '')  
065             {  
066                 return false;  
067             }  
068     
069             if ($startpos == '')  
070             {  
071                 $startpos = $filesize - $endpos;  
072                 $endpos = $filesize - 1;  
073             }  
074             else if ($endpos == '')  
075             {  
076                 $endpos = $filesize - 1;  
077             }  
078     
079             $startpos = $startpos
080             $endpos = $endpos > $filesize - 1 ? $filesize - 1 : $endpos;  
081     
082             $length = $endpos - $startpos + 1;  
083     
084             if ($length
085             {  
086                 return false;  
087             }  
088     
089             $contentlength = $length;  
090             $ispartial = true;  
091         }  
092     }  
093     
094     // send headers  
095     if ($ispartial)  
096     {  
097         header('http/1.1 206 partial content');  
098         header(content-range: bytes $startpos-$endpos/$filesize);  
099     
100     }  
101     else 
102     {  
103         header(http/1.1 200 ok);  
104         $startpos = 0;  
105         $endpos = $contentlength - 1;  
106     }  
107     
108     header('pragma: cache');  
109     header('cache-control: public, must-revalidate, max-age=0');  
110     header('accept-ranges: bytes');  
111     header('content-type: ' . $contenttype);  
112     header('content-length: ' . $contentlength);  
113     
114     if ($forcedownload)  
115     {  
116         header('content-disposition: attachment; filename=' . rawurlencode($fancyname). '');  
117     }  
118     
119     header(content-transfer-encoding: binary);  
120     
121     $buffersize = 2048;  
122     
123     if ($speedlimit != 0)  
124     {  
125         $packettime = floor($buffersize * 1000000 / $speedlimit);  
126     }  
127     
128     $bytessent = 0;  
129     $fp = fopen($filename, rb);  
130     fseek($fp, $startpos);  
131     while ($bytessent
132     {  
133         if ($speedlimit != 0)  
134         {  
135             list($usec, $sec) = explode( , microtime());  
136             $outputtimestart = ((float)$usec + (float)$sec);  
137         }  
138     
139         $readbuffersize = $contentlength - $bytessent
140         $buffer = fread($fp, $readbuffersize);  
141     
142         echo $buffer;  
143     
144         ob_flush();  
145         flush();  
146     
147         $bytessent += $readbuffersize;  
148     
149         if ($speedlimit != 0)  
150         {  
151             list($usec, $sec) = explode( , microtime());  
152             $outputtimeend = ((float)$usec + (float)$sec);  
153     
154             $usetime = ((float) $outputtimeend - (float) $outputtimestart) * 1000000;  
155             $sleeptime = round($packettime - $usetime);  
156             if ($sleeptime > 0)  
157             {  
158                 usleep($sleeptime);  
159             }  
160         }  
161     }  
162     return true;  
163 }  
164 ?>
http://www.bkjia.com/phpjc/444967.htmlwww.bkjia.comtruehttp://www.bkjia.com/phpjc/444967.htmltecharticle?php教程 002 $file_path = './download/download_cn.rar'; 003 004 //使用方法 005 downfile($file_path); 006 007 // 服务器文件路径，下载文件名字(默认为服务器文...