[Java] JSON 변환 JSON-Java org.json

gradle

// https://mvnrepository.com/artifact/org.json/json
implementation 'org.json:json:20230618'

Object to Json

User user = new User("Chris", 34);

Car car1 = new Car();
car1.setName("K5");
car1.setCarNumber("1234");
car1.setType("SUV");

Car car2 = new Car();
car2.setName("K7");
car2.setCarNumber("1111");
car2.setType("SEDAN");

List<Car> carsList = Arrays.asList(car1, car2);
user.setCars(carsList);

JSONObject car1Json = new JSONObject(car1);
System.out.println("## Object -> JSON Car : " + car1Json);
//{"carNumber":"1234","name":"K5","type":"SUV"}

JSONObject userJson = new JSONObject(user);
System.out.println("## Object -> JSON User : " + userJson);
//{"cars":[{"carNumber":"1234","name":"K5","type":"SUV"},{"carNumber":"1111","name":"K7","type":"SEDAN"}],"name":"Chris","age":34}

Text Json to Object

String userJsonString = "{\"cars\":[{\"carNumber\":\"1234\",\"name\":\"K5\",\"type\":\"SUV\"},{\"carNumber\":\"1111\",\"name\":\"K7\",\"type\":\"SEDAN\"}],\"name\":\"Chris\",\"age\":34}";

JSONObject userObject = new JSONObject(userJsonString);
System.out.println("## String -> JSONObject : " + userObject);
JSONArray carsArray = userObject.getJSONArray("cars");
System.out.println("## String -> JSONArray : " + carsArray);
//[{"carNumber":"1234","name":"K5","type":"SUV"},{"carNumber":"1111","name":"K7","type":"SEDAN"}]

JSONObject carObject = carsArray.getJSONObject(0);
System.out.println("## JSONArray -> JSONObject : " + carObject);
System.out.println("carNumber : " + carObject.get("carNumber"));
//{"carNumber":"1234","name":"K5","type":"SUV"}

Json 변환 이슈

• JSONObject 내 중첩 JSONObject를 put 할 때 toString()으로 변환하여 입력하면 
  String 값으로 자동 이스케이프 처리됨
• 변환된 String을 JSONObject로 변환 시 이스케이프 처리된 String을 JSONObject로 변환 실패

JSONObject jsonObject = new JSONObject();
jsonObject.put("car1Json", car1Json.toString());	//toString 제거 필요
System.out.println(jsonObject);
//{"car1Json":"{\"carNumber\":\"1234\",\"name\":\"K5\",\"type\":\"SUV\"}"}

String jsonString = jsonObject.toString();
JSONObject jsonObject2 = new JSONObject(jsonString);
JSONObject jsonObject3 = jsonObject2.getJSONObject("car1Json");	//객체가 아닌 문자열로 인식
System.out.println(jsonObject3);
//org.json.JSONException JSONObject["car1Json"] is not a JSONObject

 

 

https://github.com/stleary/JSON-java/tree/master

https://www.baeldung.com/java-org-json