mb_convert_encoding()不是您要实现的正确功能:您应该真正使用 html_entity_decode()代替，因为它只会转换实际的html实体改为UTF-8，并且不会影响字符串中现有的UTF-8字符.

mb_convert_encoding() isn't the correct function for what you're trying to achieve: you should really be using html_entity_decode() instead, because it will only convert the actual html entities to UTF-8, and won't affect the existing UTF-8 characters in the string.

$text = "äöü ä ö ü ß";
var_dump(html_entity_decode($text, ENT_COMPAT | ENT_HTML401, 'UTF-8'));

给出

string(18) "äöü ä ö ü ß"

演示