import('ORG.Net.Http');
$filename="1.rar";
//exit($filename);
$showname="1.rar";
Http::download($filename,$showname);


ORG.Net.Http 把下面代码去掉就好了。。为什么 大神们告诉下 下面代码什么意思呗。。感激不尽！！！
if(is_file($filename)) {
$length = filesize($filename);
}elseif(is_file(UPLOAD_PATH.$filename)) {
$filename = UPLOAD_PATH.$filename;
$length = filesize($filename);
}elseif($content != '') {
$length = strlen($content);
}else {
throw_exception($filename.L('下载文件不存在！'));
}