I have a JSON response which looks like this:
String resp = "{"name":"Renold","age":"16"}"
And I have a POJO named "Person" which contains the attributes 'Name' and 'Age'. How do I extract the attributes from the JSON response and assign them to the POJO? I have already tried GSON and the object gets incorrectly assigned as "Name = name" and "Age = age" instead of the actual response.
Any other suggestions, good lads? :)
EDIT: This is what I used with GSON
Gson gson = new Gson();
final Person p= gson.fromJson(response, Person.class);
This left me with:
p.Name = name;
p.Age = age;
instead of p.Name = Renold.
You can try this with Genson:
String resp = "{"name":"Renold","age":"16"}"
Genson genson = new Genson();
Person person = genson.deserialize(resp, Person.class);
I guess you have to use #SerializedName to map Name to name
check this pojo parse gson with invalid java names
In your Pojo you have to annotate like this.
#SerializedName("name")
private final Name;
Please try serialization using the JObject class using org.json. e.g
JSONObject jsonObj = new JSONObject("{\"name\":\"Renold\",\"age\":\"16"\"}");
Then get the properties:
jsonObj.get("name");
If you're using maven you can include the Jackson dependency. That will map things automagically.
I have used the same scenario you have described and found no issues with your code except the String representation you have used. I have put my code at pastebin. This sample project should resolve your issue of json format.
The string in your response should be:
String response = "{\"name\":\"Renold\",\"age\":16}"
Related
I need GSON mapper to throw an exception if json contains unknown fields. For example if we have POJO like
public class MyClass {
String name;
}
and json like
{
"name": "John",
"age": 30
}
I want to get some sort of message that json contains unknown field (age) that can not be deserialized.
I know there is out-of-box solution in Jackson mapper, but in our project we have been using Gson as a mapper for several years and using Jackson ends up in conflicts and bugs in different parts of project, so it is easier for me to write my own solution than using Jackson.
In other words, I want to know if there is some equivalent to Jackson's DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES in Gson. Or maybe if it can be done using Gson's DeserializationStrategy other than using reflections
I believe you cannot do it automatically with Gson.
I had to do this in a project at work. I did the following:
Gson GSON = new GsonBuilder().create();
(static final) Map<String, Field> FIELDS = Arrays.stream(MyClass.class.getDeclaredFields())
.collect(Collectors.toMap(Field::getName, Function.identity()));
JsonObject object = (JsonObject) GSON.fromJson(json, JsonObject.class);
List<String> objectProperties = object.entrySet().stream().map(Entry::getKey).collect(Collectors.toList());
List<String> classFieldNames = new ArrayList<>(FIELDS.keySet());
if (!classFieldNames.containsAll(objectProperties)) {
List<String> invalidProperties = new ArrayList<>(objectProperties);
invalidProperties.removeAll(classFieldNames);
throw new RuntimeException("Invalid fields: " + invalidProperties);
}
I need GSON mapper to throw an exception if json contains unknown fields. For example if we have POJO like
public class MyClass {
String name;
}
and json like
{
"name": "John",
"age": 30
}
I want to get some sort of message that json contains unknown field (age) that can not be deserialized.
I know there is out-of-box solution in Jackson mapper, but in our project we have been using Gson as a mapper for several years and using Jackson ends up in conflicts and bugs in different parts of project, so it is easier for me to write my own solution than using Jackson.
In other words, I want to know if there is some equivalent to Jackson's DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES in Gson. Or maybe if it can be done using Gson's DeserializationStrategy other than using reflections
I believe you cannot do it automatically with Gson.
I had to do this in a project at work. I did the following:
Gson GSON = new GsonBuilder().create();
(static final) Map<String, Field> FIELDS = Arrays.stream(MyClass.class.getDeclaredFields())
.collect(Collectors.toMap(Field::getName, Function.identity()));
JsonObject object = (JsonObject) GSON.fromJson(json, JsonObject.class);
List<String> objectProperties = object.entrySet().stream().map(Entry::getKey).collect(Collectors.toList());
List<String> classFieldNames = new ArrayList<>(FIELDS.keySet());
if (!classFieldNames.containsAll(objectProperties)) {
List<String> invalidProperties = new ArrayList<>(objectProperties);
invalidProperties.removeAll(classFieldNames);
throw new RuntimeException("Invalid fields: " + invalidProperties);
}
I am currently using JsonObject and JsonParser of com.google.gson api (using gson-2.8.5 version) to parse and read the value form input JSON.
I have JSON filed like , smaple "resultCode":"SUCCESS", when I try to read the same value from json it gives the result as ""SUCCESS"" .
Every value I am reading, getting with double "" not sure why ? You can refer below screen of my debugging screen.
I am new to Json and parser, is that default behavior ?
I am expecting "SUCCESS", "S", "00000000" not like ""SUCCESS"" or ""S""
or ""00000000""
same I have highlighted in the below image .
Please share any idea how we can get apbsolute vlaue of string without """" double quote string it causing my string comparison fail.
String response_result = "{\"response\": {\"head\": {\"function\": \"acquiring.order.create\",\"version\": \"2.0\",\"clientId\": \"201810300000\",\"reqMsgId\": \"56805892035\",\"respTime\": \"2019-09-13T13:18:08+08:00\"},\"body\": {\"resultInfo\": {\"resultCode\": \"SUCCESS\",\"resultCodeId\": \"00000000\",\"resultStatus\": S,\"resultMsg\": \"SUCCESS\"},\"acquirementId\": \"2018080834569894848930\",\"merchantTransId\": \"5683668701112717398\",\"checkoutUrl\": \"http://localhost:8081/crm/operator/operator-search-init.action\"}},\"signature\":\"d+TUYLvt1a491R1e6aO8i9VwXWzVhfNgnhD0Du74f4RgBQ==\"}";
HttpInvoker.Result result = i.new Result(200, response_result);
JsonObject jo = new JsonParser().parse(response_result).getAsJsonObject();
String resultCode = jo.get("response").getAsJsonObject().get("body").getAsJsonObject().get("resultInfo").getAsJsonObject().get("resultCode").toString();
String resultCodeId = jo.get("response").getAsJsonObject().get("body").getAsJsonObject().get("resultInfo").getAsJsonObject().get("resultCodeId").toString();
String resultStatus = jo.get("response").getAsJsonObject().get("body").getAsJsonObject().get("resultInfo").getAsJsonObject().get("resultStatus").toString();
String checkoutUrl = jo.get("response").getAsJsonObject().get("body").getAsJsonObject().get("checkoutUrl").toString();
if ( RESULT_CODE_GCASH_SUCCESS.equals(resultCode)
&& RESULT_STATUS_SUCCESS.equals(resultStatus)
&& StringUtils.isNotEmpty(checkoutUrl)) {
log.error("Testing ".concat(resultCode).concat(resultStatus).concat(checkoutUrl));
}
log.error("Testing ".concat(resultCode).concat(resultStatus).concat(checkoutUrl));
}
This is my input JSON
{
"response":{
"head":{
"function":"acquiring.order.create",
"version":"2.0",
"clientId":"201810300000",
"reqMsgId":"56805892035",
"respTime":"2019-09-13T13:18:08+08:00"
},
"body":{
"resultInfo":{
"resultCode":"SUCCESS",
"resultCodeId":"00000000",
"resultStatus":"S",
"resultMsg":"SUCCESS"
},
"acquirementId":"2018080834569894848930",
"merchantTransId":"5683668701112717398",
"checkoutUrl":"http://localhost:8081/crm/operator/operator-search-init.action"
}
},
"signature":"d+TUYLvtI38YL2hresd98Ixu1BXccvvh1IQMiHuMXUEeW/N5exUsW491R1e6aO8i9VwXWzVhfNgnhD0Du74f4RgBQ=="
}
JsonParser parses your json into JsonElement structure. The behaviour that you see is a normal since you are using toString method of JsonElement. To achieve your goal just use JsonElement::getAsString method :
String resultCode = jo.get("response").getAsJsonObject().get("body").getAsJsonObject().get("resultInfo").getAsJsonObject().get("resultCode").getAsString();
which gives SUCCESS instead of "SUCCESS"
Note that JsonElement is an abstract class and classes, that extend this class, will override those helper getAs... methods. In your case JsonPrimitive::getAsString will be invoked.
Also you could create a POJO class for your json and use Gson::fromJson to parse json into object of your POJO class.
With the input from #Michalk:
I understand that easy way to read JSON data is using Gson::fromJson and creating POJO class for out json.
I have generated POJO Classes supplying my sample input JSON using this link
and Now I have POJO Classes called : CreateOrderJSONResponse
Gson::fromJson
Sample :
Gson gson = new Gson();
CreateOrderJSONResponse responseJson = gson.fromJson(inputJSON, CreateOrderJSONResponse.class);
Accessubg data :
String resultCodeText = responseJson.getResponse().getBody().getResultInfo().getResultCode();
String resultCodeId = responseJson.getResponse().getBody().getResultInfo().getResultCodeId();
String resultStatus = responseJson.getResponse().getBody().getResultInfo().getResultStatus();
String checkoutUrl = responseJson.getResponse().getBody().getCheckoutUrl();
Above Gson::fromJson example works smooth and it looks neat compare to direct accessing the filed with below sample code :
JsonObject jo = parser.parse(inputJSON).getAsJsonObject();
String resultCodeText = jo.get("response").getAsJsonObject().get("body").getAsJsonObject().get("resultInfo").getAsJsonObject().getAsJsonPrimitive("resultCode").getAsString();
String resultCodeId = jo.get("response").getAsJsonObject().get("body").getAsJsonObject().get("resultInfo").getAsJsonObject().getAsJsonPrimitive("resultCodeId").getAsString();
String resultStatus = jo.get("response").getAsJsonObject().get("body").getAsJsonObject().get("resultInfo").getAsJsonObject().getAsJsonPrimitive("resultStatus").getAsString();
String checkoutUrl = jo.get("response").getAsJsonObject().get("body").getAsJsonObject().getAsJsonPrimitive("checkoutUrl").getAsString();
Note :
I have found this link of JSON or JAVA, SCALA, POJO generator tools as GitHub access you can access here
My servlet recieves/loads multiple parameters from/for an article (price, id, count, name).
While they are saved in the session for other purposes I want to display them in a Shopping cart.
So my idea was to get all values into a json like this
{"id":1, "prductName":"article1"}
but my json always ends up empty.
I had two approaches:
String prname = request.getParameter("name");
String anz = String.valueOf(session.getAttribute("Anzahl"));
String prid = request.getParameter("id");
String price = request.getParameter("price");
These are my parameters:
First try:
class ToJson{
String prname1 = String.valueOf(session.getAttribute("prname"));
String anz1 = String.valueOf(session.getAttribute("Anzahl"));
String prid1 = String.valueOf(session.getAttribute("id"));
String price1 = String.valueOf(session.getAttribute("price"));
}
ToJson obj = new ToJson();
Jsonb jsonb = JsonbBuilder.create();
String jsn1 = jsonb.toJson(obj);
Ends up with: {}
Second try:
ArrayList<String> ar = new ArrayList<String>();
ar.add(prname);
ar.add(price);
ar.add(prid);
ar.add(anz);
ToJson obj = new ToJson();
Jsonb jsonb = JsonbBuilder.create();
String jsn = jsonb.toJson(ar);
Ends up with: ["P1neu","25","1","145"]
It isn't in a format I wanted and I also don't know how to access the seperate values here, I tried jsn[1] but it didnt work.
Could you help me, please?
To your first question, why JSON object is printing empty:
You are missing getters & setters in the ToJSON class for JSON Builder/Parser to access the properties/fields, and that's why its printing as empty object.
To your second question, how do I access JSON properties:
JSON representation is a natively a string representation, and you can't read part of string as jsn[1].
For reading JSON object properties, you convert it into POJO using available any of preferred open source parser libraries like Jacksons, Gson etc. And then access POJO properties using standard java getter/setters.
I have searched the web for answer and everywhere is done like this:
JSONObject params = new JSONObject();
Gson gson = new Gson();
params.put("Event", gson.toJson(myEvent));
But this is returning me Json like this with all escapings on ":
"Event":"{\"Test1\":\"TestValue1\",\"TestObj\":{\"Test2\":\"TestValue2\",\"Test3\":\"TestValue3\"...
How can I have Json free of all escapings, just like this:
"Event":"{"Test1":"testValue1","TestObj":{"Test2":"testValue2","Test3":"testValue3"...
Cheers mates.
I can pass the object like this, property by property:
createEvent.put("Test1", myObj1.Test1);
createEvent.put("Test2", myObj2.Test2);
and pass the Json to api, but Notes is with escapings:
String myNoteListJson = new Gson().toJson(myNoteList);
createEvent.put("Notes", myNoteListJson);
I found an answer, here it is:
I am passing property by property:
createEvent.put("Test1", myObj1.Test1);
createEvent.put("Test2", myObj2.Test2);
and the Notelist problem is solved like this:
JSONArray mJSONArray = new JSONArray(myNoteList);
createEvent.put("Notes", mJSONArray);