$content = iconv("utf-8","gb2312//IGNORE",$content); //utf-8转gbk
$content = iconv("gb2312","utf-8//IGNORE",$content); //gb2312换为utf-8
$content = iconv("utf-8","gb2312//IGNORE",$content); //utf-8转gbk
$content = iconv("gb2312","utf-8//IGNORE",$content); //gb2312换为utf-8