java - Jackson - Recursive parsing into Map<String, Object>

Question

I'm trying to simplify my code: I want to store key and values (all strings).

I'm actually using a Map<String, Object> to store it. hat way Object could be a value (String) or a new node (Map<String, Object>).

How could I simplify this code? A recursive function would be good.

try {
    JsonParser jsonParser = new JsonFactory().createJsonParser(content);

    jsonParser.nextToken();
    while (jsonParser.nextToken() != JsonToken.END_OBJECT) {
        jsonParser.nextToken();

        if (jsonParser.getCurrentToken() == JsonToken.START_OBJECT) {
            while (jsonParser.nextToken() != JsonToken.END_OBJECT) {
                String key = jsonParser.getCurrentName();
                jsonParser.nextToken();

                if (jsonParser.getCurrentToken() == JsonToken.START_OBJECT) {
                    mData.put(key, new HashMap<String, Object>());
                    while (jsonParser.nextToken() != JsonToken.END_OBJECT) {
                        String subkey = jsonParser.getCurrentName();
                        jsonParser.nextToken();

                        if (jsonParser.getCurrentToken() == JsonToken.START_OBJECT) {
                            Map<String, Object> subdata = (Map<String, Object>) mData.get(key);
                            subdata.put(subkey, new HashMap<String, Object>());
                            while (jsonParser.nextToken() != JsonToken.END_OBJECT) {
                                String subsubkey = jsonParser.getCurrentName();
                                jsonParser.nextToken();
                                Map<String, Object> subsubdata = (Map<String, Object>) subdata.get(subkey);
                                LogHelper.d("data[" + key + "][" + subkey + "][" + subsubkey + "]=" + jsonParser.getText());
                                subsubdata.put(subsubkey, jsonParser.getText());
                            }
                        }
                        else {
                            LogHelper.d("data[" + key + "]=" + jsonParser.getText());
                            mData.put(key, jsonParser.getText());
                        }
                    }
                }
                else {
                    LogHelper.d("data[" + key + "]=" + jsonParser.getText());
                    mData.put(key, jsonParser.getText());
                }
            }
        }
        else {
            LogHelper.d("status=" + jsonParser.getText());
            mStatus = jsonParser.getText();
        }
    }
}
catch (IllegalArgumentException e) {
    error("0", "IllegalArgumentException: " + e.getMessage());
}
catch (JsonParseException e) {
    error("0", "IOException: " + e.getMessage());
}
catch (IOException e) {
    error("0", "IOException: " + e.getMessage());
}

Answer 1

Assuming that your end goal is just to deserialize JSON into a Map<String, Object>, there is a far simpler way to do this with Jackson. Using ObjectMapper:

final String json = "{}";
final ObjectMapper mapper = new ObjectMapper();
final MapType type = mapper.getTypeFactory().constructMapType(
    Map.class, String.class, Object.class);
final Map<String, Object> data = mapper.readValue(json, type);

You will need error handling etc, but this is a good starting point.