<?php
/* 
 * 豆蔻的博文 http://www.dotcoo.com
 * $str 原始字符串
 * $encoding 原始字符串的编码，默认GBK
 * $prefix 编码后的前缀，默认"&#"
 * $postfix 编码后的后缀，默认";"
 */
function unicode_encode($str, $encoding=''GBK'', $prefix=''&#'', $postfix='';''){
 $str = iconv($encoding, ''UCS-2'', $str);
 $arrstr = str_split($str, 2);
 $unistr = '''';
 for($i=0, $len=count($arrstr); $i<$len; $i++)
 {
  $dec = hexdec(bin2hex($arrstr[$i]));
  $unistr .= $prefix.$dec.$postfix;
 }
 return $unistr;
}

/*
 * 豆蔻的博文 http://www.dotcoo.com
 * $str Unicode编码后的字符串
 * $encoding 原始字符串的编码，默认GBK
 * $prefix 编码字符串的前缀，默认"&#"
 * $postfix 编码字符串的后缀，默认";"
 */
function unicode_decode($unistr, $encoding=''GBK'', $prefix=''&#'', $postfix='';''){
 $arruni = explode($prefix, $unistr);
 $unistr = '''';
 for($i = 1, $len = count($arruni); $i<$len; $i++)
 {
  if(strlen($postfix) > 0) {
   $arruni[$i] = substr($arruni[$i], 0, strlen($arruni[$i])-strlen($postfix)); }
  $temp = intval($arruni[$i]);
  $unistr .= ($temp < 256) ? chr(0).chr($temp) : chr($temp/256).chr($temp%256);
 }
 return iconv(''UCS-2'', $encoding, $unistr);
}

//GBK字符串测试
$str = ''<b>哈哈</b>'';
echo $str.''<br />'';

$unistr = unicode_encode($str);
echo $unistr.''<br />''; // &#60;&#98;&#62;&#21704;&#21704;&#60;&#47;&#98;&#62;

$str2 = unicode_decode($unistr);
echo $str2.''<br />''; //<b>哈哈</b>

//UTF-8字符串测试
$utf8_str = iconv(''GBK'', ''UTF-8'', $str);
echo $utf8_str.''<br />''; // <b>鍝堝搱</b> 注：UTF在GBK下显示的乱码！可切换浏览器的编码测试

$utf8_unistr = unicode_encode($utf8_str, ''UTF-8'');
echo $utf8_unistr.''<br />''; // &#60;&#98;&#62;&#21704;&#21704;&#60;&#47;&#98;&#62;

$utf8_str2 = unicode_decode($utf8_unistr, ''UTF-8'');
echo $utf8_str2.''<br />''; // <b>鍝堝搱</b>

//其它后缀、前缀测试
$prefix_unistr = unicode_encode($str, ''GBK'', "\\u", '''');
echo $prefix_unistr.''<br />''; // \u60\u98\u62\u21704\u21704\u60\u47\u98\u62

$profix_unistr2 = unicode_decode($prefix_unistr, ''GBK'', "\\u", '''');
echo $profix_unistr2.''<br />''; //<b>哈哈</b>
?>