PHP使用json_encode函数时不转义中文的解决方法

echo json_encode(array('你好'));
// 输出: ["\u4f60\u597d"]

class Util
{
    static function json_encode($input){
        // 从 PHP 5.4.0 起, 增加了这个选项.
        if(defined('JSON_UNESCAPED_UNICODE')){
            return json_encode($input, JSON_UNESCAPED_UNICODE);
        }
        if(is_string($input)){
            $text = $input;
            $text = str_replace('\\', '\\\\', $text);
            $text = str_replace(
                array("\r", "\n", "\t", "\""),
                array('\r', '\n', '\t', '\\"'),
                $text);
            return '"' . $text . '"';
        }else if(is_array($input) || is_object($input)){
            $arr = array();
            $is_obj = is_object($input) || (array_keys($input) !== range(0, count($input) - 1));
            foreach($input as $k=>$v){
                if($is_obj){
                    $arr[] = self::json_encode($k) . ':' . self::json_encode($v);
                }else{
                    $arr[] = self::json_encode($v);
                }
            }
            if($is_obj){
                return '{' . join(',', $arr) . '}';
            }else{
                return '[' . join(',', $arr) . ']';
            }
        }else{
            return $input . '';
        }
    }
}