java 怎么遍历json

public static void main(String[] args) {

    String s = "{'A':{'a':'1' ,'aa':'11'},'B':{'b':'2' ,'bb':'22'}}" ;
    JSONObject jsonObject1=JSONObject.fromObject(s);
    Iterator<String> iterator1 =jsonObject1.keys();
    while(iterator1.hasNext()){
        String key1 = iterator1.next();
        String value1 = jsonObject1.getString(key1);
        System.out.println(key1);
        JSONObject jsonObject2=JSONObject.fromObject(value1);
        Iterator<String> iterator2 =jsonObject2.keys();
        while(iterator2.hasNext()){
            String key2 = iterator2.next();
            String value2 = jsonObject2.getString(key2);
            System.out.println(" - "+key2);
            System.out.println(" -- "+value2);
        }
    }
}