**
     * 微信api不支持中文转义的json结构
     * @param array $arr
     */
    static function json_encode($arr) {
        $parts = array ();
        $is_list = false;
        //Find out if the given array is a numerical array
        $keys = array_keys ( $arr );
        $max_length = count ( $arr ) - 1;
        if (($keys [0] === 0) && ($keys [$max_length] === $max_length )) { //See if the first key is 0 and last key is length - 1
            $is_list = true;
            for($i = 0; $i < count ( $keys ); $i ++) { //See if each key correspondes to its position
                if ($i != $keys [$i]) { //A key fails at position check.
                    $is_list = false; //It is an associative array.
                    break;
                }
            }
        }
        foreach ( $arr as $key => $value ) {
            if (is_array ( $value )) { //Custom handling for arrays
                if ($is_list)
                    $parts [] = self::json_encode ( $value ); /* :RECURSION: */
                else
                    $parts [] = ‘"‘ . $key . ‘":‘ . self::json_encode ( $value ); /* :RECURSION: */
            } else {
                $str = ‘‘;
                if (! $is_list)
                    $str = ‘"‘ . $key . ‘":‘;
                //Custom handling for multiple data types
                if (is_numeric ( $value ) && $value<2000000000)
                    $str .= $value; //Numbers
                elseif ($value =http://www.mamicode.com/== false)"‘ . addslashes ( $value ) . ‘"‘; //All other things
                // :TODO: Is there any more datatype we should be in the lookout for? (Object?)
                $parts [] = $str;
            }
        }
        $json = implode ( ‘,‘, $parts );
        if ($is_list)
            return ‘[‘ . $json . ‘]‘; //Return numerical JSON
        return ‘{‘ . $json . ‘}‘; //Return associative JSON
    }