$txtContent = iconv("utf-8",'GBK',$txtContent);

utf-8直接轉gbk，這樣問題就來了，當有些字符無法轉換的時候就從此處斷開，導致內容不完整。后來又重新查手冊，才發現iconv還有兩個可選的輔助參數：TRANSLIT和IGNORE ，(其中IGNORE 就是說遇到無法轉換的就跳過)。 其實也怪自己太粗心，剛開始一看iconv函數參數就三個，而且例子中也沒有特別的，就懶得去看英文解釋了，直接使用，直到出現了問題。

string iconv ( string in_charset, string out_charset, string str )

Performs a character set conversion on the string str from in_charset to out_charset. Returns the converted string or FALSE on failure.

If you append the string //TRANSLIT to out_charset transliteration is activated. This means that when a character can't be represented in the target charset, it can be approximated through one or several similarly looking characters. If you append the string //IGNORE, characters that cannot be represented in the target charset are silently discarded. Otherwise, str is cut from the first illegal character.