I'm making a web app using Jersey and Jackson. I've made a response POJO of the following type:
#JsonInclude(Include.NON_NULL)
public class ResponsePojo {
private Integer id;
private String name;
private String imageUrl;
private JsonObject queryParams;
public ResponsePojo(Integer id, String name, String imageUrl, JsonObject queryParams) {
this.id = id;
this.name = name;
this.imageUrl = imageUrl;
this.queryParams = queryParams;
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getImageUrl() {
return imageUrl;
}
public void setImageUrl(String imageUrl) {
this.imageUrl = imageUrl;
}
public JsonObject getQueryParams() {
return queryParams;
}
public void setQueryParams(JsonObject queryParams) {
this.queryParams = queryParams;
}
}
I receive a proper JSON response from the webAPI when I omit the private JsonObject queryParams; field. How can I return a JSON from inside the response POJO?
I'm receiving the following error:
Direct self-reference leading to cycle (through reference chain: my.package.Response["list"]->java.util.ArrayList[0]->my.package.ResponsePojo["queryParams"]->com.google.gson.JsonObject["asJsonObject"])
Related
Recently at a test, I came across a problem to do some processing after querying the response data from a restful service. I had to write a web service consumer and do some processing using Java.
While I was able to consume the service using Http classes from jdk, I didn't knew of any way to map the response json in their respective pojo's, without using Jackson's or other external mapper libraries.
Now I have been trying to do that. Until now I have tried to change the incoming Json to byte array and deserialize and map into the pojo, but that didn't worked. I remember with JAX-B unmarshalling was possible but it has been carved out of jdk after java 8, and I have been working with higher version JDK 11.
I also tried getting the response as streams but then data processing does not remains equally straightforward, as it would have been in case of working with model classes. I am in split, any way out of it would be very appreciable ..
HttpRequest req = HttpRequest
.newBuilder(new URI("https://jsonmock.hackerrank.com/api/transactions/search?userId=4"))
.GET().build();
//HttpResponse<byte[]> response = HttpClient.newHttpClient().send(r, BodyHandlers.ofByteArray());
HttpResponse<Stream<String>> response = HttpClient.newHttpClient().send(req, BodyHandlers.ofLines());
Stream<String> responseStream = response.body();
Natively you can do it using Regex and plenty complex custom logic assuming you handling the JSON as string changing the response Line as below.
HttpResponse response = HttpClient.newHttpClient().send(req, HttpResponse.BodyHandlers.ofString());
I assume that the models you could use are below
Location Model
`
public class Location {
private int id;
private String address;
private String city;
private int zipCode;
public Location(int id, String address, String city, int zipCode) {
this.id = id;
this.address = address;
this.city = city;
this.zipCode = zipCode;
}
public Location() {
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
public String getCity() {
return city;
}
public void setCity(String city) {
this.city = city;
}
public int getZipCode() {
return zipCode;
}
public void setZipCode(int zipCode) {
this.zipCode = zipCode;
}
}
`
User Model
`
public class User {
private int id;
private int userId;
private String userName;
private double timestamp;
private String txnType;
private String amount;
private Location location;
private String ip;
public User(int id, int userId, String userName, double timestamp, String txnType, String amount, Location location, String ip) {
this.id = id;
this.userId = userId;
this.userName = userName;
this.timestamp = timestamp;
this.txnType = txnType;
this.amount = amount;
this.location = location;
this.ip = ip;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public int getUserId() {
return userId;
}
public void setUserId(int userId) {
this.userId = userId;
}
public String getUserName() {
return userName;
}
public void setUserName(String userName) {
this.userName = userName;
}
public double getTimestamp() {
return timestamp;
}
public void setTimestamp(double timestamp) {
this.timestamp = timestamp;
}
public String getTxnType() {
return txnType;
}
public void setTxnType(String txnType) {
this.txnType = txnType;
}
public String getAmount() {
return amount;
}
public void setAmount(String amount) {
this.amount = amount;
}
public Location getLocation() {
return location;
}
public void setLocation(Location location) {
this.location = location;
}
public String getIp() {
return ip;
}
public void setIp(String ip) {
this.ip = ip;
}
}
`
Generally Java has not any build in parser. You may find this below
Java Built-in data parser for JSON or XML or else
The most simple library you might find is described here
https://www.oracle.com/technical-resources/articles/java/json.html
and you might find it as maven dependency below
https://mvnrepository.com/artifact/org.json/json
To do that you would have to write your own Json parser that would do the same as Jackson, Gson Simple Json or any other external Json library. In other words you would be re-inventing the wheel. While it might be very interesting it would be pretty useless. That is why those libraries have been written in the first place.
I would like to iterate Products and get the list of name,code and price and set in my Model class. Any help would be really appreciated - how can I iterate this. When I use obj.get("Products") - it just printing as string - got stuck to iterate.
{
"id": "skd3303ll333",
"Products": [{
"name": "apple",
"code": "iphone-393",
"price": "1939"
},
{
"name": "ipad",
"code": "ipad-3939",
"price": "900"
}
]
}
#PostMapping(path="/create", consumes=MediaType.APPLICATION_JSON_VALUE)
public ResponseEntity<Object> create(#RequestBody Map<String, Object> obj ) {
System.out.println("Products :" + obj.get("Products"));
}
There are two ways to do this,
1) By type casting (personally i will not prefer this)
List<Map<Object,Object>> productslist = (List<Map<Object, Object>>) obj.get("products");
for(Map entry: productslist) {
for(Object s: entry.keySet()) {
System.out.println(s.toString());
System.out.println(entry.get(s).toString());
}
}
2) Mapping directly to Model class, for this approach you need Jackson library in buildpath
#JsonIgnoreProperties(unknown =true)
public class Customer {
#JsonProperty("id")
private String id;
#JsonProperty("products")
private List<Products> products;
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public List<Products> getProducts() {
return products;
}
public void setProducts(List<Products> products) {
this.products = products;
}
}
#JsonIgnoreProperties(unknown =true)
class Products{
#JsonProperty("name")
private String name;
#JsonProperty("code")
private String code;
#JsonProperty("price")
private String price;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getCode() {
return code;
}
public void setCode(String code) {
this.code = code;
}
public String getPrice() {
return price;
}
public void setPrice(String price) {
this.price = price;
}
}
Controller
public ResponseEntity<Object> create(#RequestBody Customer obj ) {
You need POJO structure with two classes:
public class Product {
private String name;
private String code;
private int price;
}
public class ProductsGroup {
private long id;
private List<Product> products;
// getters/setters
}
And change your method signature to:
#PostMapping(path="/create", consumes=MediaType.APPLICATION_JSON_VALUE)
public ResponseEntity<ProductsGroup> create(#RequestBody ProductsGroup productGroup)
{
System.out.println("Products :" + productGroup.getProducts());
}
You are trying to process the json using a Map<String, Object> obj, which could be possible in some way, but mostly what you want to do is define a single or multiple POJO classes. These represent the json.
public class IdWrapper {
private String id;
#JsonProperty("Products")
private List<Product> products;
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public List<Product> getProducts() {
return products;
}
}
public class Product {
private String name;
private String code;
private String price;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getCode() {
return code;
}
public void setCode(String code) {
this.code = code;
}
public String getPrice() {
return price;
}
public void setPrice(String price) {
this.price = price;
}
}
And in you controller like this:
#RestController
#RequestMapping("test")
public class DemoController {
#PostMapping()
public void test(#RequestBody IdWrapper productsWrapper) {
System.out.println();
}
}
The result variable contains corrected parsed JSON.
But after deserialization List contains correct amount of items but all of them are empty.
How to fix it?
Gson gson = new Gson();
List<UnitView> unitViews = new ArrayList<UnitView>();
// https://stackoverflow.com/questions/5554217/google-gson-deserialize-listclass-object-generic-type
Type typeToken = new TypeToken<List<UnitView>>() { }.getType();
unitViews = gson.fromJson(result,typeToken);
Even if I do like
UnitView[] unitViews = gson.fromJson(result, UnitView[].class);
The fields of items are empty as well.
UnitView
public class UnitView implements Serializable {
public String id ;
public String name ;
public String description ;
public String deviceTypeName ;
public String categoryID ;
public String lastOnline ;
public String latitude ;
public String longitude ;
public String atTime ;
public String getId() {
return id;
}
public String getName() {
return name;
}
public String getDescription() {
return description;
}
public String getDeviceTypeName() {
return deviceTypeName;
}
public String getCategoryID() {
return categoryID;
}
public String getLastOnline() {
return lastOnline;
}
public String getLatitude() {
return latitude;
}
public String getLongitude() {
return longitude;
}
public String getAtTime() {
return atTime;
}
public void setId(String id) {
this.id = id;
}
public void setName(String name) {
this.name = name;
}
public void setDescription(String description) {
this.description = description;
}
public void setDeviceTypeName(String deviceTypeName) {
this.deviceTypeName = deviceTypeName;
}
public void setCategoryID(String categoryID) {
this.categoryID = categoryID;
}
public void setLastOnline(String lastOnline) {
this.lastOnline = lastOnline;
}
public void setLatitude(String latitude) {
this.latitude = latitude;
}
public void setLongitude(String longitude) {
this.longitude = longitude;
}
public void setAtTime(String atTime) {
this.atTime = atTime;
}
}
JSON DATA
[{"ID":"294","Name":"Foton Tunland № F110","Description":null,"DeviceTypeName":"Техника ТО","CategoryID":"18","LastOnline":"19.12.2017 20:38:04","Latitude":"11,40119","Longitude":"11,42403","AtTime":"19.12.2017 20:38:04"},{"ID":"295","Name":"DML LP1200 № 9793","Description":null,"DeviceTypeName":"Буровой станок дизельный","CategoryID":"15","LastOnline":null,"Latitude":null,"Longitude":null,"AtTime":null}]
Ok , the problem is that the parser is case-sensitive, you can change the name of your attributes to match the name of the json value of you could use the SerializedName annotation like this:
#SerializedName("ID")
public String id ;
#SerializedName("Name")
public String name ;
#SerializedName("Description")
public String description;
...
or
public String ID ;
public String Name ;
public String Description ;
...
I think you're having this problem because of null values in your json.
Check it. Source
I want to add post.java between DataRetriver.java code .Because i want to use pojo object and post.java has pojo object. I think I can add id = array_items.optInt("id"); but i know it.
DataRetriver.java
for (int i = 0; i < names_count; i++) {
JSONObject array_items = jsonArray.getJSONObject(i);
ListValues jsonValues, pictureValue;
switch (type) {
case 1:
id = array_items.optInt("id");
name = array_items.optString("name");
jsonValues = new ListValues(id, name);
listValues.add(jsonValues);
break;
case 2:
id = array_items.optInt("userId");
name = array_items.optString("title");
if (id == recieved_id) {
jsonValues = new ListValues(id, name);
listValues.add(jsonValues);
}
break;
Post.java
public class Post implements Serializable {
#SerializedName("userId")
private int userId;
#SerializedName("name")
#Expose
public String name;
#SerializedName("id")
private int id;
#SerializedName("title")
private String title;
#SerializedName("body")
private String body;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getUserId() {
return userId;
}
public void setUserId(int userId) {
this.userId = userId;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public String getBody() {
return body;
}
public void setBody(String body) {
this.body = body;
}
}
Your advice important for me
Thank you!
I am trying to get some the array of actors from Jira. The code for the wrapper is used in a Gson.fromJson call. I had used something similar with a json string that did not have an array in it that had the information I needed and it worked fine, so the issue seems to do with the array, but I am not 100% sure:
import com.google.gson.annotations.SerializedName;
public class JiraRoleJsonWrapper {
#SerializedName("self")
private String self;
#SerializedName("name")
private String name;
#SerializedName("id")
private int id;
#SerializedName("description")
private String description;
#SerializedName("actors")
private JiraActors[] actors;
public JiraActors[] getActors() {
return actors;
}
public void setActors(JiraActors[] actors) {
this.actors = actors;
}
public String getSelf() {
return self;
}
public void setSelf(String self) {
this.self = self;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getDescription() {
return description;
}
public void setDescription(String key) {
this.description = description;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
/*
public String[] getAvatarUrls() {
return avatarUrls;
}
public void setAvatarUrls(String[] avatarUrls) {
this.avatarUrls = avatarUrls;
}
*/
}
class JiraActors {
#SerializedName("id")
private int id;
#SerializedName("displayNme")
private String displayName;
#SerializedName("type")
private String type;
#SerializedName("name")
private String name;
//#SerializedName("avatarUrl")
//private String avatarUrl;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getDisplayName() {
return displayName;
}
public void setDisplayName(String displayName) {
this.displayName = displayName;
}
public String getType() {
return type;
}
public void setType(String type) {
this.type = type;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
The json it would receive:
{
"self":"http://someserver.com:8080/apps/jira/rest/api/2/project/10741/role/10002",
"name":"Administrators",
"id":10002,
"description":"A project role",
"actors":[
{
"id":12432,
"displayName":"Joe Smith",
"type":"atlassian-user-role-actor",
"name":"joesmi",
"avatarUrl":"/apps/jira/secure/useravatar?size=xsmall&ownerId=dawsmi&avatarId=12245"
},
{
"id":12612,
"displayName":"Smurfette Desdemona",
"type":"atlassian-user-role-actor",
"name":"smudes",
"avatarUrl":"/apps/jira/secure/useravatar?size=xsmall&ownerId=lamade&avatarId=10100"
},
This shows two actors and the format of the json. Please note I did not put a complete json response. It just shows two actors.
In my code, I tried the following to retrieve the actors:
InputStream is = response.getEntityInputStream();
Reader reader = new InputStreamReader(is);
Gson gson = new Gson();
JiraRoleJsonWrapper[] jiraRoleJsonWrapper = gson.fromJson(reader, JiraRoleJsonWrapper[].class);
for (JiraRoleJsonWrapper w : jiraRoleJsonWrapper) {
JiraActors[] a = w.getActors();
String name = a.getName();
It does not find getName for some reason. I am not sure why.
I figured it out.
I change the setActors to
public void setActors(ArrayList<JiraActors> actors) {
this.actors = actors;
}
Then I was able to get the array list and get access to the getName() method of JiraActors.