php支持多线程下载

主要用到了http协议中的RANGE相关的内容.

header("Cache-Control: public");
header("Accept-Ranges: bytes");

$file = "a.7z";
$filename = "a.7z";

$size=filesize($file);
$size1=$size-1;
//获得字节范围
if(isset($_SERVER['HTTP_RANGE'])) {
   list($name, $range) = explode("=",$_SERVER['HTTP_RANGE']);
   $length=$size1-$range;
   header("HTTP/1.1 206 Partial Content");  //http协议头状态码,表示以部分内容传输
   header("Content-Range: bytes ".$range."-".$size1."/".$size);
}else{
   $length = $size;
}

header("Content-Length: $length");
header("Content-Type: application/octet-stream");
header("Content-Disposition: attachment; filename=".$filename);

$fp=fopen($file,"rb");

//设定文件指针位置
fseek($fp,$range);

while(!feof($fp)){
   set_time_limit(0);
   echo fread($fp,1024);
   flush();
   ob_flush();
}
fclose($fp);
exit;
?>