1 获取当前字符串的编码
$encode = mb_detect_encoding($str, array("ASCII",‘UTF-8‘,"GB2312","GBK",‘BIG5‘));
2 将字符编码改为utf-8
$str_encode = mb_convert_encoding($str, ‘UTF-8‘, $encode);
下面举例子:把一个字符串（utf-8）编码改为gbk
$file = "C:\\Users\\Administrator\\Desktop\\中文.xls"; $file = iconv(‘utf-8‘, ‘gb2312‘, $file);
或
$file = "C:\\Users\\Administrator\\Desktop\\中文.xls"; //自动获取字符串编码 $encode = mb_detect_encoding($file, array("ASCII",‘UTF-8‘,"GB2312","GBK",‘BIG5‘)); $file = mb_convert_encoding($file, ‘GB2312‘, $encode);
参考：http://www.php.net/manual/zh/book.iconv.php
原文：http://www.cnblogs.com/fps2tao/p/8016493.html