Develop Reference

Get Json / Resonse body from Curl Post Request in Java

This is the method I have written which sends a POST request to send an Email.
I am able to send the email and get the Response Code 200 Ok.
But I don't know how to get the JSON Response and convert it into an Object.
Can someone please tell me how to do this?
public void sendEmail() {
try {
URL url = new URL("https://mandrillapp.com/api/1.0/messages/send");
HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
httpURLConnection.setRequestMethod("POST");
httpURLConnection.setDoOutput(true);
httpURLConnection.setRequestProperty("Content-Type", "application/json");
String data =
"{\"key\": \"" + mailchimpApiKey + "\", " +
"\"message\": {" +
"\"from_email\": \"from#gmail.com\", " +
"\"subject\": \"Hello World\", " +
"\"text\": \"Welcome to Mailchimp Transactional!\", " +
"\"to\": [{ \"email\": \"to#gmail.com\", \"type\": \"to\" }]}}";
byte[] out = data.getBytes(StandardCharsets.UTF_8);
OutputStream stream = httpURLConnection.getOutputStream();
stream.write(out);
System.out.println(httpURLConnection.getResponseCode() + " " + httpURLConnection.getResponseMessage());
httpURLConnection.disconnect();
} catch (IOException e) {
e.printStackTrace();
}
}

A basic search reveals: https://www.baeldung.com/httpurlconnection-post#8-read-the-response-from-input-stream
try(BufferedReader br = new BufferedReader(
new InputStreamReader(con.getInputStream(), "utf-8"))) {
StringBuilder response = new StringBuilder();
String responseLine = null;
while ((responseLine = br.readLine()) != null) {
response.append(responseLine.trim());
}
System.out.println(response.toString());
}
If the response is in JSON format, use any third-party JSON parsers such as Jackson library, Gson, or org.json to parse the response.

In addition to the answer by #mdre
I use the org.json library to convert responses into JSON Objects. The following method does exactly this:
import org.json.JSONException;
import org.json.JSONObject;
public static JSONObject convertResponseToJSONObject(String responseString) {
try {
JSONObject jsonObj = new JSONObject(responseString);
return jsonObj;
} catch (JSONException e) {
System.err.println(
"It is not possible to create a JSONObject from the input string, returning null. Exception:");
e.printStackTrace();
}
return null;
}
Note that the response only represents a JSON object if it starts with a {. If it starts with a [ the response represents a JSON array.

You can get errorStream or inputStream based on the response code you receive and get the response from it. Below example creates a BufferedReader from the stream
BufferedReader br = null;
if (100 <= httpURLConnection.getResponseCode() && httpURLConnection.getResponseCode() <= 399) {
br = new BufferedReader(new InputStreamReader(httpURLConnection.getInputStream()));
} else {
br = new BufferedReader(new InputStreamReader(httpURLConnection.getErrorStream()));
}
You can then read from the br and store data based on your requirement. Below will store data into StringBuilder
StringBuilder data = new StringBuilder();
String dataLine = null;
while ((dataLine = br.readLine()) != null) {
data.append(dataLine.trim());
}
System.out.println(data.toString());
Instead of printing as String you can also convert it into JSON by using JSON libraries. You may follow this guide

Parse JSON array of objects from url Java

How do I parse an array of JSON objects from an external URL with the Java application? Here is an example of code, that I am using:
URL connectionUrl = new URL(/*some url*/);
connection = (HttpURLConnection) connectionUrl.openConnection();
String postData = "/*some post data*/";
connection.setDoOutput(true);
connection.setFixedLengthStreamingMode(postData.length());
OutputStream outputStream = null;
outputStream = connection.getOutputStream();
outputStream.write(postData.getBytes());
if(connection.getResponseCode() == 200) {
InputStream inputStream = connection.getInputStream();
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
String magicString = "", magicLine;
while((magicLine = bufferedReader.readLine()) != null) {
JSONArray jsonArr = new JSONArray(magicLine);
for(int i = 0; i < jsonArr.length(); i++) {
JSONObject currentEntity = jsonArr.getJSONObject(i);
}
}
return magicString;
And this one is the array of JSON objects, that gets echo'd out on some external URL:
[{"ID":"1","name":"test name","phone":"+37120000000","email":"test#cream.camp","date":"2020-12-17","time":"18:50:00","people_num":"4","active":"0"},{"ID":"2","name":"test name","phone":"+37120000000","email":"test#cream.camp","date":"2020-12-17","time":"18:50:00","people_num":"4","active":"1"}]
Unfortunately, the application fails with the following error:
org.json.JSONException: Value Authorization of type java.lang.String cannot be converted to JSONArray

You can create a POJO to hold JSON response. Use third-party jar such as Jackson. Something like the following:
ObjectMapper mapper = new ObjectMapper();
try {
YourPOJO obj = mapper.readValue(new URL("http://jsonplaceholder.typicode.com/posts/7"), YourPOJO.class);
System.out.println(usrPost);
} catch (Exception e) {
e.printStackTrace();
}
Refer to https://www.java2novice.com/java-json/jackson/jackson-client-read-from-api-url/

How to support multi language in GSON (between Json and Java Object)?

In my project , i separated back-end and front-end modules and run by providing REST api from back-end and call it by using Apache Http Client and GSON.
I want to provide multiple language like German,French... on UI(webpage).
On webpage , It shows like this "Schl��ssli Sch��negg, Wilhelmsh��he" , but in database and RestAPI json is "Schlössli Schönegg" .
How can I support multi language?
In back-end , i wrote Request methods like get,put,post and In Front-end, i used HttpClient and GSON to convert JSON to/from Java Object.
I tried inside the html but main problem is from GSON when it convert fromJSON() , the original JSON value ""Schlössli Schönegg" become "Schl��ssli Sch��negg, Wilhelmsh��he".
In RestAPI , JSON data is
{
"addressId": 3,
"buildingName": "Schlössli Schönegg",
"street": "Wilhelmshöhe",
"ward": "6003",
"district": "luzern",
"cityOrProvince": "luzern state",
"country": "Switzerland"
}
But in Front-end , Java Object String Data after GSON convert is
(..buildingName=Schlössli Schönegg, street=Wilhelmshöhe, ward=6003, district=luzern, cityOrProvince=luzern state, country=Switzerland)
Here , RestClient function code
public List<FakeEmployeeDTO> getAllEmployeeList() throws IOException {
HttpClient client = HttpClientBuilder.create().build();
HttpGet getRequest = new HttpGet(URL);
HttpResponse response = client.execute(getRequest);
Integer statusCode = response.getStatusLine().getStatusCode();
if (statusCode != 200) {
throw new SystemException(ERROR_MESSAGE + statusCode);
}
BufferedReader rd = new BufferedReader(new InputStreamReader(response.getEntity().getContent()));
String line = "";
StringBuilder jsonData = new StringBuilder();
while ((line = rd.readLine()) != null) {
jsonData.append(line);
}
response.getEntity().getContent().close();
rd.close();
logger.info(jsonData.toString());
Gson gson = new GsonBuilder().setDateFormat("dd-MMM-yyyy").create();
Type listType = new TypeToken<List<FakeEmployeeDTO>>() {
}.getType();
List<FakeEmployeeDTO> employeeList = gson.fromJson(jsonData.toString(), listType);
sortEmployeeListByFirstName(employeeList);
return employeeList;
}
Inside Employee, I have address atrribute , inside that address i have value like buildingNumber and Street, that value can be in any languages.

Try with this
(BufferedReader rd = new BufferedReader( new InputStreamReader(response.getEntity().getContent(),
"UTF-8"));)
Entire Code will end up with like this.
public List<FakeEmployeeDTO> getAllEmployeeList() throws IOException {
HttpClient client = HttpClientBuilder.create().build();
HttpGet getRequest = new HttpGet(url);
HttpResponse response = client.execute(getRequest);
Integer statusCode = response.getStatusLine().getStatusCode();
if (statusCode != 200) {
throw new SystemException(ERROR_MESSAGE + statusCode);
}
BufferedReader rd = new BufferedReader( new InputStreamReader(response.getEntity().getContent(),
"UTF-8")); // if it is not working please try with ("ISO-8859-1")
String line = "";
StringBuilder jsonData = new StringBuilder();
while ((line = rd.readLine()) != null) {
jsonData.append(line);
}
response.getEntity().getContent().close();
rd.close();
logger.info(jsonData.toString());
Gson gson = new GsonBuilder().setDateFormat("dd-MMM-yyyy").create();
Type listType = new TypeToken<List<FakeEmployeeDTO>>() {
}.getType();
List<FakeEmployeeDTO> employeeList = gson.fromJson(jsonData.toString(), listType);
sortEmployeeListByFirstName(employeeList);
return employeeList;}
Next time make sure to try with this, because you can use "try with resource"
try (BufferedReader reader = new BufferedReader(new InputStreamReader(
new URL("https://htt.your url.com" + URLEncoder.encode(query, "UTF-8") )
.openConnection().getInputStream()))) {

Can not find the Json object (Using org.json)

Microsoft Academic provided an API to get some general information from Microsoft academic. The response type is a Json Object. Using org.Json and following code, I have tried to read the response object but I have failed (need to download these jars + common-logging and common-codec) :
URIBuilder builder = new URIBuilder("https://api.projectoxford.ai/academic/v1.0/evaluate?");
builder.setParameter("expr", "Composite(AA.AuN=='jaime teevan')");
builder.setParameter("count", "100");
builder.setParameter("attributes", "Ti,CC");
URI uri = builder.build();
HttpGet request = new HttpGet(uri);
request.setHeader("Ocp-Apim-Subscription-Key", "Your-Key");
HttpClient httpclient = HttpClients.createDefault();
HttpResponse response = httpclient.execute(request);
HttpEntity entity = response.getEntity();
if (entity != null) {
JSONObject obj = new JSONObject(entity);
JSONArray arr = obj.getJSONArray("entities");
for (int i = 0; i < arr.length(); i++){
String post_id = arr.getJSONObject(i).getString("Ti");
System.out.println(post_id);
}
System.out.println(EntityUtils.toString(entity));
}
Which returns the following exception:
Exception in thread "main" org.json.JSONException: JSONObject["entities"] not found.
at org.json.JSONObject.get(JSONObject.java:471)
at org.json.JSONObject.getJSONArray(JSONObject.java:618)
How to fix this?
EDIT
Although it is easy to see an example of the response from the link I provided at the beginning of my question (Microsoft Academic), but for ease of readers I show it in here:
{
"expr": "Composite(AA.AuN=='jaime teevan')",
"entities":
[
{
"logprob": -15.08,
"Ti": "personalizing search via automated analysis of interests and activities",
"CC": 372,
},
{
"logprob": -15.389,
"Ti": "the perfect search engine is not enough a study of orienteering behavior in directed search",
"CC": 237,
}
]
}

Seems like the problem to me is you are not converting your response to string , you need to convert your response to string before passing it to JSONObject
HttpEntity entity = response.getEntity();
ByteArrayOutputStream os = new ByteArrayOutputStream();
try {
entity.writeTo(os);
} catch (IOException e1) {
}
String contentString = new String(os.toByteArray());
or other way is
InputStream instream = entity.getContent();
BufferedReader reader = new BufferedReader(new InputStreamReader(instream));
StringBuilder sb = new StringBuilder();
String line = null;
try {
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
is.close();
} catch (IOException e) {
e.printStackTrace();
}
}
String contentString = sb.toString(); // you can pass sb.toString() directly to jsonobject as well
and now pass contentString to JSONObject
JSONObject obj = new JSONObject(contentString);
JSONArray arr = obj.getJSONArray("entities");
Update : your can also use this which is also suggested by #Ömer Fadıl Usta
but i would strongly recommend to use HttpURLConnection for security and performance

Try to pass string JsonData to JSONObject :
if (entity != null) {
String jsonData = EntityUtils.toString(entity);
JSONObject obj = new JSONObject(jsonData);
........
.....
}

process in-app apple receipt with java

I am using a java backend. After a user performs an in-app purchase, the front-end sends me the receipt. In turn, I am to send the receipt to apple for confirmation; then apple is to decode the receipt and send me back a JSON dictionary. My question is about sending the receipt back to apple so that I may get the json response. I am using the code below. But I keep getting {"status":21002} from apple and something about "Invalid cookie header". Any ideas how to solve this?
String url = "https://buy.itunes.apple.com/verifyReceipt";
DefaultHttpClient client = null;
try {
String input = IOUtils.toString(is);
log.info("THE INPUTSTREAM: " + input);
JSONObject receipt = new JSONObject();
receipt.put("receipt-data", input);
client = new DefaultHttpClient();
HttpPost post = new HttpPost(url);
StringEntity entity = new StringEntity(receipt.toString());
entity.setContentType("application/json");
post.setEntity(entity);
HttpClientParams.setRedirecting(post.getParams(), false);
HttpResponse response = client.execute(post);
if (300 <= response.getStatusLine().getStatusCode()) {
throw new RuntimeException("No response from iTune store. status code: " + response.getStatusLine().getStatusCode());
}
if (null == response.getEntity()) {
log.info("Response is null");
throw new Exception("Response is null");
}
StringBuilder sb = new StringBuilder();
BufferedReader reader = new BufferedReader(new InputStreamReader(response.getEntity().getContent()));
for (String line; null != (line = reader.readLine());) {
sb.append(line);
}
JSONObject json = new JSONObject(sb.toString());
log.info("THE JSON" + json);
//Then work with json below
} catch (Exception e) {
throw new WebApplicationException(Response.status(Status.BAD_REQUEST).entity(e.getMessage()).build());
} finally {
if (null != client) {
client.getConnectionManager().shutdown();
}
}

No need cookie I think? try
HttpClientParams.setCookiePolicy(client.getParams(), CookiePolicy.IGNORE_COOKIES);