function sendFile($serverPath, $filename,$charset = 'UTF-8', $mimeType = 'application/octet-stream')
{
	// 文件名乱码问题
	if (preg_match("/MSIE/", $_SERVER["HTTP_USER_AGENT"])) {
		$filename = urlencode($filename);
		$filename = str_replace("+", "%20", $filename);// 替换空格
		$attachmentHeader = "Content-Disposition: attachment; filename=\"{$filename}\"; charset={$charset}";
	} else if (preg_match("/Firefox/", $_SERVER["HTTP_USER_AGENT"])) {			
		$attachmentHeader = 'Content-Disposition: attachment; filename*="utf8\'\'' . $filename. '"' ;
	} else {
		$attachmentHeader = "Content-Disposition: attachment; filename=\"{$filename}\"; charset={$charset}";
	}
	
	
	$filesize = filesize($serverPath);

	//header("Pragma: public");   header("Expires: 0");
	header("Cache-Control: must-revalidate, post-check=0, pre-check=0");
	header("Content-Type: application/force-download");
	header("Content-Type: {$mimeType}");

	header($attachmentHeader);
	header('Pragma: cache');
	header('Cache-Control: public, must-revalidate, max-age=0');
	header("Content-Length: {$filesize}");
	readfile($serverPath);
	exit;
}