Question

I know it is very easy to use Jackson to convert Map to Json. But I want to know if there is a better way for my situation. Below is my code.

String jsonInfo = "{\"attr\":\"value\",\"attr2\",\"value2\"}";

ObjectMapper mapper = new ObjectMapper();
Map<String,Object> map = new HashMap<String,Object>();
map.put("name","daniel");
map.put("info",mapper.readValue(jsonInfo, new TypeReference<Map>(){}));

String finalJsonString = mapper.writeValueAsString(map);

As you can see, even I already know jsonInfo is a json string. For this part, I convert it into a map then finally let Jackson convert it to json again. Is there any better way that I can avoid such duplicated work?

Answer 1

You just want to use Jackson to parse your JSON into its tree structure where you can then add data. This eliminates the extra step of serializing/deserializing to a POJO (or Map)

String jsonInfo = "{\"attr\":\"value\",\"attr2\":\"value2\"}";
ObjectMapper mapper = new ObjectMapper();
JsonNode origNode = mapper.readTree(jsonInfo);

ObjectNode rootNode = mapper.createObjectNode();
rootNode.put("name", "daniel");
rootNode.put("info", origNode);

String finalJson = rootNode.toString();

Your finalJson then becomes:

{“name”:”daniel”,”info”:{“attr”:”value”,”attr2″:”value2″}}

Note that JsonNode is immutable, but can be cast to an ObjectNode if you wanted to modify your original JSON as well.