按照性能从高到低依次是iconv,mbstring和自制字库，下面的代码简单演示了一下！其他代码互转也差不多
PHP CODE

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<?
function encode_conver($subject,$function){
switch ($function){
case 1:
$subject=iconv("GB2312","UTF-8",$subject);
break;
case 2:
$subject=mb_convert_encoding($subject, "UTF-8", "GB2312");
break;
case 3:
$subject=gb2utf8($subject);
break;
}
return $subject;
}
function gb2utf8($string)
{
$ut="";
$gb=file("./gbk.txt");
$gb=explode("|",$gb[0]);
$utf=file("./utf8.txt");
$utf=explode("|",$utf[0]);
$gb=array_flip($gb);
while ($string){
$st=substr($string,0,1);
$string=substr($string,1);
if (ord($st)<128){
$ut.=$st;
} else {
$st.=substr($string,0,1);
$string=substr($string,1);
$ut.=$utf[$gb[$st]];
}
}
return $ut;
}?>

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