php的json_encode不兼容JSON_UNESCAPED_UNICODE

//php的json_encode不兼容JSON_UNESCAPED_UNICODE的解决方案
function _json_encode($value) {
if (version_compare(PHP_VERSION, '5.4.0', '<')) {
$str = json_encode($value);
$str = preg_replace_callback(
"#\\\u([0-9a-f]{4})#i", function($matchs) {
return iconv('UCS-2BE', 'UTF-8', pack('H4', $matchs[1]));
}, $str
);
return $str;
} else {
return json_encode($value, JSON_UNESCAPED_UNICODE);
}
}