PHP输出CSV文件出现乱码问题

问题:PHP输入用户列表为csv文件,用excel打开显示为乱码,用记事本或ue打开正常.查看文件编码显示为utf-8

解决:
function down_file($filepath,$filename)
{
if(!file_exists($filepath))
{
echo "backup error ,download file no exist";
exit();
}
ob_end_clean();
header('Content-Type: application/download');
header("Content-type: text/csv");
header('Content-Disposition: attachment;filename="'.$filename.'"');
header("Content-Encoding: binary");
  header("Content-Length:".filesize($filepath));
header("Pragma: no-cache");
header("Expires: 0");
readfile($filepath);
$e=ob_get_contents();
ob_end_clean();
}

$fname='usersdata.csv';
$handle=fopen($fname,'wb');
$strUsersData =iconv('utf-8','gb2312',$strUsersData);//转换编码
if(fwrite($handle,$strUsersData)==false){}
fclose($handle);
down_file($fname,'555.csv');