PHP 大文件下载（方式3 支持断点续传）
$fileStat = stat($fileName); $lastModified = $fileStat['mtime'];$md5 = md5($fileStat['mtime'] .'='. $fileStat['ino'] .'='. $fileStat['size']);
$etag = '"' . $md5 . '-' . crc32($md5) . '"';
header('Last-Modified: ' . gmdate("D, d M Y H:i:s", $lastModified) . ' GMT');
header("ETag: $etag");
if (isset($_SERVER['HTTP_IF_MODIFIED_SINCE']) && strtotime($_SERVER['HTTP_IF_MODIFIED_SINCE']) >= $lastModified)
{
header("HTTP/1.1 304 Not Modified");
return true;
}
if (isset($_SERVER['HTTP_IF_UNMODIFIED_SINCE']) && strtotime($_SERVER['HTTP_IF_UNMODIFIED_SINCE']) < $lastModified)
{
header("HTTP/1.1 304 Not Modified");
return true;
}
if (isset($_SERVER['HTTP_IF_NONE_MATCH']) &&$_SERVER['HTTP_IF_NONE_MATCH'] == $etag)
{
header("HTTP/1.1 304 Not Modified");
return true;
}
if ($fancyName == '')
{
$fancyName = basename($fileName);
}
if ($contentType == '')
{
$contentType = 'application/octet-stream';
}
$fileSize = $fileStat['size'];
$contentLength = $fileSize;
$isPartial = false;
if (isset($_SERVER['HTTP_RANGE']))
{
if (preg_match('/^bytes=(\d*)-(\d*)$/', $_SERVER['HTTP_RANGE'], $matches))
{
$startPos = $matches;
$endPos = $matches;
if ($startPos == '' && $endPos == '')
{
return false;
}
if ($startPos == '')
{
$startPos = $fileSize - $endPos;
$endPos = $fileSize - 1;
}
else if ($endPos == '')
{
$endPos = $fileSize - 1;
}
$startPos = $startPos < 0 ? 0 : $startPos;
$endPos = $endPos > $fileSize - 1 ? $fileSize - 1 : $endPos;
$length = $endPos - $startPos + 1;
if ($length < 0)
{
return false;
}
$contentLength = $length;
$isPartial = true;
}
}
// send headers
if ($isPartial)
{
header('HTTP/1.1 206 Partial Content');
header("Content-Range: bytes $startPos-$endPos/$fileSize");
}
else
{
header("HTTP/1.1 200 OK");
$startPos = 0;
$endPos = $contentLength - 1;
}
header('Pragma: cache');
header('Cache-Control: public, must-revalidate, max-age=0');
header('Accept-Ranges: bytes');
header('Content-type: ' . $contentType);
header('Content-Length: ' . $contentLength);
if ($forceDownload)
{
header('Content-Disposition: attachment; filename="' . rawurlencode($fancyName). '"');
}
header("Content-Transfer-Encoding: binary");
$bufferSize = 2048;
if ($speedLimit != 0)
{
$packetTime = floor($bufferSize * 1000000 / $speedLimit);
}
$bytesSent = 0;
$fp = fopen($fileName, "rb");
fseek($fp, $startPos);
while ($bytesSent < $contentLength && !feof($fp) && connection_status() == 0 )
{
if ($speedLimit != 0)
{
list($usec, $sec) = explode(" ", microtime());
$outputTimeStart = ((float)$usec + (float)$sec);
}
$readBufferSize = $contentLength - $bytesSent < $bufferSize ? $contentLength - $bytesSent : $bufferSize;
$buffer = fread($fp, $readBufferSize);
echo $buffer;
ob_flush();
flush();
$bytesSent += $readBufferSize;
if ($speedLimit != 0)
{
list($usec, $sec) = explode(" ", microtime());
$outputTimeEnd = ((float)$usec + (float)$sec);
$useTime = ((float) $outputTimeEnd - (float) $outputTimeStart) * 1000000;
$sleepTime = round($packetTime - $useTime);
if ($sleepTime > 0)
{
usleep($sleepTime);
}
}
}
return true;
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