How to convert JSON to a Java object

Currently, it is quite simple to convert a Java object to a JSON object. However, it is more complicated to convert a JSON object to a Java object.

The first method is JSON-lib.

The second method is JACKSON.

The first two methods are relatively easy for relatively simple Pojo objects. However, compared with nested multi-layer data, the complexity is directly increased.

The third method is solved using GOOGLE's Gson. Anyone who has written about Android knows that this is a Google product. The biggest benefit is that it basically does not rely on other packages. It is naturally easy to use, and the value method is flexible. Complete the complicated JSON values.

Gson has two concepts. One is JsonObject and JsonArray. Specific Code

Package com. mycompany. gsondata; import com. google. gson. jsonArray; import com. google. gson. jsonObject; import com. google. gson. jsonParser;/*** Hello world! **/Public class App {public static void main (String [] args) {String jsonData = "{\" questionnaireID \ ": \" QNTest \", \ "answerResults \": [{\ "questionID \": \ "QSTest01 \", \ "anserContent \": \ "cfb7f441-9086-11e3-8cf8-000c2945c442 \"}, {\ "questionID \": \ "QSTest01 \", \ "anserContent \": \ "cfb7f441-9086-11e3-8cf8-000c2945c442 \" },{ \ "questionID \": \ "QSTest03 \", \ "anserContent \": \ "6b3a9cce-9087-11e3-8cf8-000c2945c442, a086331d-9087-11e3-8cf8-000c2945c442 \" },{ \ "questionID \": \ "QSTest01 \", \ "anserContent \": \ "cfb7f441-9086-11e3-8cf8-000c2945c442 \"}, {\ "questionID \": \ "QSTest05 \", \ "anserContent \": \ "test text blank \" },{ \ "questionID \": \ "QSTest06 \", \ "anserContent \": \ "3 \" },{ \ "questionID \": \ "QSTest07 \", \ "anserContent \": \ "2.2 \"}]} "; JsonObject root = new JsonParser (). parse (jsonData ). getAsJsonObject (); System. out. println (root. get ("questionnaireID "). toString (); // directly obtain the root node value JsonArray AnswerList = root. getAsJsonArray ("answerResults"); // retrieves an array for (int I = 0; I <AnswerList. size (); I ++) {System. out. println (AnswerList. get (I ). getAsJsonObject (). get ("questionID "). toString (); System. out. println (AnswerList. get (I ). getAsJsonObject (). get ("anserContent "). toString ());}}}