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How to obtain json reponse from http request?

When trying to retrieve the response json from my api I can only ever get a string value which I am unable to convert to jsonobject to use.
Should respond with json format {"result":"success","client[id]":"1"}
But I am only able to retrieve string "result=success,client[id]=1"
public void createWHMCSUser(final String emailID, final String random, final String uid) {
Thread thread = new Thread(new Runnable() {
#Override
public void run() {
try {
String e = URLEncoder.encode(emailID, "utf-8");
String r = URLEncoder.encode(random, "utf-8");
URL url = new URL("http://create.user.com/includes/api.php?action=AddClient&username=abc123&password=abc123&accesskey=abc123&firstname=User&lastname=Name&email=" + e +"&address1=na&city=na&state=na&poscode=00000&country=US&phonenumber=0000000000&password2=" + r + "&reponsetype=json");
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod("POST");
conn.setRequestProperty("Content-Type", "application/json");
conn.setRequestProperty("Accept","application/json");
conn.setDoOutput(true);
conn.setDoInput(true);
Log.i("STATUS", String.valueOf(conn.getResponseCode()));
Log.i("MSG", conn.getResponseMessage());
if(conn.getResponseCode() == 200){
BufferedReader in = new BufferedReader(new InputStreamReader(conn.getInputStream()));
String readAPIResponse = " ";
StringBuilder jsonString = new StringBuilder();
while((readAPIResponse = in.readLine()) != null){
jsonString.append(readAPIResponse);
JSONObject obj = new JSONObject(jsonString.toString());
int aJsonString = obj.getInt("Client[id]");
SetClientID(uid,aJsonString);
}
in.close();
}
conn.disconnect();
} catch (Exception e) {
e.printStackTrace();
}
}
});
thread.start();
}

use this way more easier and fast
for more examples and to built library check this :
enter link description here
AndroidNetworking.get("URL")
.setTag("test")
.setPriority(Priority.MEDIUM)
.build()
.getAsJSONObject(new JSONObjectRequestListener() {
#Override
public void onResponse(JSONObject response) {
// handle your response here
}
#Override
public void onError(ANError error) {
// handle error
}
});

Use the json library to add the java object to JSONObject. That will store all the java object content in to json string format in your server code. That will convert In to json format.
Then you will return the code from server as the regular string.
In the client side, you will receive it as the string.
Then you need to convert it to java object from the json string. That is the actual json string. You will e able to convert that string to java obj.
But what you have return is not the json String. That is just string only.

Handling a Json API response with java

I've been trying to figure out how to handle the json response from a GET request. This is the code I have for the request:
String urlString = URL I want to request;
URL url = new URL(urlString);
URLConnection conn = url.openConnection();
InputStream is = conn.getInputStream();
String response = getStringFromInputStream(is);
My question is what to do now. I've been playing with gson but I cannot figure out how to parse the response for the required information.
I also found this method somewhere online to turn the response into a string:
private static String getStringFromInputStream(InputStream is) {
BufferedReader br = null;
StringBuilder sb = new StringBuilder();
String line;
try {
br = new BufferedReader(new InputStreamReader(is));
while ((line = br.readLine()) != null) {
sb.append(line);
}
} catch (IOException e) {
e.printStackTrace();
} finally {
if (br != null) {
try {
br.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
return sb.toString();
}
If anyone could help me parse the string or somehow otherwise handle the response I'd really appreciate it.

You can use Jackson framework to parse the response into Java Object. Once you add the dependency, this is how it will work:
Let's say you are getting the below response from the API:
{
"id": 1,
"name": "foo"
}
You can write the following code to deserialise it into an Object:
public class Response {
private int id;
private String name;
//Getters and Setters
}
//code to convert
String response = sb.toString();
ObjectMapper mapper = new ObjectMapper();
Response responseObject = mapper.readValue(response, Response.class);
If the json is not valid, it will fail and throw JsonParseException or JsonMappingException. You can handle it in your code and respond accordingly.
Here's step by step tutorial on how to use Jackson.

It depends on the what you want to do with Json.I am assuming you want to convert in into an Java object.
For that you can use Gson or Jackson.
Suppose you have a json like
{"userId":"1","userName":"Yasir"}
and your java class like
class User{
int userId;
String userName;
//setters and getters
}
then you can use something like
Gson gson = new Gson();
User user= gson.fromJson(jsonInString, User.class);
to create java object.

Mapping Id String from JSON to POJO breaks the String?

I'm currently integrating with an API, and when I send a POST request which creates an "order", I receive a JSON response which looks like:
{ "OrderCreateResult": 15764514 }
However, when I map this JSON into a POJO which looks like:
#Data
#AllArgsConstructor
public class CreateCircleGraphicsOrderResponse {
private String OrderCreateResult;
}
and I map it via gson like this:
if (response.isSuccessful()) {
CreateCircleGraphicsOrderResponse orderResponse = gson.fromJson(response.body().string(), CreateCircleGraphicsOrderResponse.class);
response.close();
return orderResponse;
}
However, when I retrieve the string via orderResponse.getOrderCreateResult(), and print the string, it indeed is the string I expect, but sending that returned String as a query param for a GET request sends an invalid request, as orderResponse.getOrderCreateResult().equals("15764514") == False
Why would the String be broken when mapping to a POJO, even when it prints the same as copy and pasting the string?
This is the GET Request:
public CircleGraphicsGetOrder getOrder(String circleGraphicsOrderId) {
try {
this.getOrderUrl = this.getOrderUrl.concat(circleGraphicsOrderId);
URL url = new URL(this.getOrderUrl);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod("GET");
conn.setRequestProperty("Accept", "application/json");
conn.connect();
BufferedReader br = new BufferedReader( new InputStreamReader(
conn.getInputStream(), "UTF-8" ) );
StringBuilder sb = new StringBuilder( 2048 );
for( String line; (line = br.readLine()) != null; ) {
sb.append( line );
}
conn.disconnect();
return null;
} catch(IOException ex) {
throw new IOException(ex.getMessage());
}
}
And the Error message:
java.io.IOException: Server returned HTTP response code: 504 for URL: https://rest.cgorders.com/api/orders/order?access_token=97484431a4525ed2b294b699a3d2f202&id=15764573
FINAL EDIT:
I was able to solve this problem by making sure that the "OrderCreateResult" field was an int, and then casting it to a string in the concatenation phase by calling String.valueOf(orderCreateResult).

How to consume a json object via post method from client

I have a json object and i need topass it to my server via post.The json is hard coded inside my client. Below is my server program(test.java) - please note this is for learning purpose. So explain it clearly...
#Path("/json/product")
public class Test {
#POST
#Path("/post")
#Consumes(MediaType.APPLICATION_JSON)
public Response createProductInJSON() {
return Response.status(201).entity(....).build();
}
}
how json is gets passed from client to server?
I followed http://www.mkyong.com/webservices/jax-rs/restful-java-client-with-jersey-client/ tutorial by mkyong(confused about post method).
From a client program a hard coded json format needed to pass and recieved via post method...at server.
Can the json pass from client to server as parameters...?
or else how to do it....
below is my sample client program....
public static void main(String[] args) {
try {
URL url = new URL("http://localhost:8080/Snapshothealthapp1/rest/json/product/post");
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setDoOutput(true);
conn.setRequestMethod("POST");
conn.setRequestProperty("Content-Type", "application/json");
String JSON_DATA =
"{"
+ " \"SnapshotRequest\": ["
+ " {"
+ " \"AuthenticationType\": \"email\","
+ " \"EmailAddress\": \"test#gmail.com\","
+ " \"Password\" : \"12345\","
+ " \"PracticeID\" : \"null\","
+ " \"DeviceID\" : \"null\""
+ " } + ]"
+ "}";
// request.body("application/json", JSON_DATA);
// String input = "{\"singer\":\"Metallica\",\"title\":\"Fade To Black\"}";
OutputStream os = conn.getOutputStream();
os.write(JSON_DATA.getBytes());
os.flush();
if (conn.getResponseCode() != HttpURLConnection.HTTP_CREATED) {
throw new RuntimeException("Failed : HTTP error code : "
+ conn.getResponseCode());
}
BufferedReader br = new BufferedReader(new InputStreamReader(
(conn.getInputStream())));
String output;
System.out.println("Output from Server .... \n");
while ((output = br.readLine()) != null) {
System.out.println(output);
}
conn.disconnect();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
I need to pass the string json data to my server.Can anyone please give a client and server code for this?
Advance thanks

Add #Consumes as "application/json" and specify the method parameter in JsonObject Type. You must have added javax.json.jar (normally comes with JAX-RS ) .
#Path("/create")
#POST
#Consumes (MediaType.APPLICATION_JSON) //Specify the POST MediaType as "application/json"
#Produces(MediaType.APPLICATION_JSON)
public Book createBook(JsonObject postData //Consumable JSON Object param ) {
System.out.println( postData); //This prints the client's JSON object from the Request Body
//Do your work here with the postData ..........
String value1 = postData.getString("key1");
int value2 = postData.getInt("key2");
//................
//........
//.....
}

Java - sending HTTP parameters via POST method easily

I am successfully using this code to send HTTP requests with some parameters via GET method
void sendRequest(String request)
{
// i.e.: request = "http://example.com/index.php?param1=a&param2=b&param3=c";
URL url = new URL(request);
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setDoOutput(true);
connection.setInstanceFollowRedirects(false);
connection.setRequestMethod("GET");
connection.setRequestProperty("Content-Type", "text/plain");
connection.setRequestProperty("charset", "utf-8");
connection.connect();
}
Now I may need to send the parameters (i.e. param1, param2, param3) via POST method because they are very long.
I was thinking to add an extra parameter to that method (i.e. String httpMethod).
How can I change the code above as little as possible to be able to send paramters either via GET or POST?
I was hoping that changing
connection.setRequestMethod("GET");
to
connection.setRequestMethod("POST");
would have done the trick, but the parameters are still sent via GET method.
Has HttpURLConnection got any method that would help?
Is there any helpful Java construct?
Any help would be very much appreciated.

In a GET request, the parameters are sent as part of the URL.
In a POST request, the parameters are sent as a body of the request, after the headers.
To do a POST with HttpURLConnection, you need to write the parameters to the connection after you have opened the connection.
This code should get you started:
String urlParameters = "param1=a&param2=b&param3=c";
byte[] postData = urlParameters.getBytes( StandardCharsets.UTF_8 );
int postDataLength = postData.length;
String request = "http://example.com/index.php";
URL url = new URL( request );
HttpURLConnection conn= (HttpURLConnection) url.openConnection();
conn.setDoOutput( true );
conn.setInstanceFollowRedirects( false );
conn.setRequestMethod( "POST" );
conn.setRequestProperty( "Content-Type", "application/x-www-form-urlencoded");
conn.setRequestProperty( "charset", "utf-8");
conn.setRequestProperty( "Content-Length", Integer.toString( postDataLength ));
conn.setUseCaches( false );
try( DataOutputStream wr = new DataOutputStream( conn.getOutputStream())) {
wr.write( postData );
}

Here is a simple example that submits a form then dumps the result page to System.out. Change the URL and the POST params as appropriate, of course:
import java.io.*;
import java.net.*;
import java.util.*;
class Test {
public static void main(String[] args) throws Exception {
URL url = new URL("http://example.net/new-message.php");
Map<String,Object> params = new LinkedHashMap<>();
params.put("name", "Freddie the Fish");
params.put("email", "fishie#seamail.example.com");
params.put("reply_to_thread", 10394);
params.put("message", "Shark attacks in Botany Bay have gotten out of control. We need more defensive dolphins to protect the schools here, but Mayor Porpoise is too busy stuffing his snout with lobsters. He's so shellfish.");
StringBuilder postData = new StringBuilder();
for (Map.Entry<String,Object> param : params.entrySet()) {
if (postData.length() != 0) postData.append('&');
postData.append(URLEncoder.encode(param.getKey(), "UTF-8"));
postData.append('=');
postData.append(URLEncoder.encode(String.valueOf(param.getValue()), "UTF-8"));
}
byte[] postDataBytes = postData.toString().getBytes("UTF-8");
HttpURLConnection conn = (HttpURLConnection)url.openConnection();
conn.setRequestMethod("POST");
conn.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
conn.setRequestProperty("Content-Length", String.valueOf(postDataBytes.length));
conn.setDoOutput(true);
conn.getOutputStream().write(postDataBytes);
Reader in = new BufferedReader(new InputStreamReader(conn.getInputStream(), "UTF-8"));
for (int c; (c = in.read()) >= 0;)
System.out.print((char)c);
}
}
If you want the result as a String instead of directly printed out do:
StringBuilder sb = new StringBuilder();
for (int c; (c = in.read()) >= 0;)
sb.append((char)c);
String response = sb.toString();

I couldn't get Alan's example to actually do the post, so I ended up with this:
String urlParameters = "param1=a&param2=b&param3=c";
URL url = new URL("http://example.com/index.php");
URLConnection conn = url.openConnection();
conn.setDoOutput(true);
OutputStreamWriter writer = new OutputStreamWriter(conn.getOutputStream());
writer.write(urlParameters);
writer.flush();
String line;
BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream()));
while ((line = reader.readLine()) != null) {
System.out.println(line);
}
writer.close();
reader.close();

I find HttpURLConnection really cumbersome to use. And you have to write a lot of boilerplate, error prone code. I needed a lightweight wrapper for my Android projects and came out with a library which you can use as well: DavidWebb.
The above example could be written like this:
Webb webb = Webb.create();
webb.post("http://example.com/index.php")
.param("param1", "a")
.param("param2", "b")
.param("param3", "c")
.ensureSuccess()
.asVoid();
You can find a list of alternative libraries on the link provided.

import java.net.*;
public class Demo{
public static void main(){
String data = "data=Hello+World!";
URL url = new URL("http://localhost:8084/WebListenerServer/webListener");
HttpURLConnection con = (HttpURLConnection) url.openConnection();
con.setRequestMethod("POST");
con.setDoOutput(true);
con.getOutputStream().write(data.getBytes("UTF-8"));
con.getInputStream();
}
}

i have read above answers and have created a utility class to simplify HTTP request. i hope it will help you.
Method Call
// send params with Hash Map
HashMap<String, String> params = new HashMap<String, String>();
params.put("email","me#example.com");
params.put("password","12345");
//server url
String url = "http://www.example.com";
// static class "HttpUtility" with static method "newRequest(url,method,callback)"
HttpUtility.newRequest(url,HttpUtility.METHOD_POST,params, new HttpUtility.Callback() {
#Override
public void OnSuccess(String response) {
// on success
System.out.println("Server OnSuccess response="+response);
}
#Override
public void OnError(int status_code, String message) {
// on error
System.out.println("Server OnError status_code="+status_code+" message="+message);
}
});
Utility Class
import java.io.*;
import java.net.*;
import java.util.HashMap;
import java.util.Map;
import static java.net.HttpURLConnection.HTTP_OK;
public class HttpUtility {
public static final int METHOD_GET = 0; // METHOD GET
public static final int METHOD_POST = 1; // METHOD POST
// Callback interface
public interface Callback {
// abstract methods
public void OnSuccess(String response);
public void OnError(int status_code, String message);
}
// static method
public static void newRequest(String web_url, int method, HashMap < String, String > params, Callback callback) {
// thread for handling async task
new Thread(new Runnable() {
#Override
public void run() {
try {
String url = web_url;
// write GET params,append with url
if (method == METHOD_GET && params != null) {
for (Map.Entry < String, String > item: params.entrySet()) {
String key = URLEncoder.encode(item.getKey(), "UTF-8");
String value = URLEncoder.encode(item.getValue(), "UTF-8");
if (!url.contains("?")) {
url += "?" + key + "=" + value;
} else {
url += "&" + key + "=" + value;
}
}
}
HttpURLConnection urlConnection = (HttpURLConnection) new URL(url).openConnection();
urlConnection.setUseCaches(false);
urlConnection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded"); // handle url encoded form data
urlConnection.setRequestProperty("charset", "utf-8");
if (method == METHOD_GET) {
urlConnection.setRequestMethod("GET");
} else if (method == METHOD_POST) {
urlConnection.setDoOutput(true); // write POST params
urlConnection.setRequestMethod("POST");
}
//write POST data
if (method == METHOD_POST && params != null) {
StringBuilder postData = new StringBuilder();
for (Map.Entry < String, String > item: params.entrySet()) {
if (postData.length() != 0) postData.append('&');
postData.append(URLEncoder.encode(item.getKey(), "UTF-8"));
postData.append('=');
postData.append(URLEncoder.encode(String.valueOf(item.getValue()), "UTF-8"));
}
byte[] postDataBytes = postData.toString().getBytes("UTF-8");
urlConnection.setRequestProperty("Content-Length", String.valueOf(postDataBytes.length));
urlConnection.getOutputStream().write(postDataBytes);
}
// server response code
int responseCode = urlConnection.getResponseCode();
if (responseCode == HTTP_OK && callback != null) {
BufferedReader reader = new BufferedReader(new InputStreamReader(urlConnection.getInputStream()));
StringBuilder response = new StringBuilder();
String line;
while ((line = reader.readLine()) != null) {
response.append(line);
}
// callback success
callback.OnSuccess(response.toString());
reader.close(); // close BufferReader
} else if (callback != null) {
// callback error
callback.OnError(responseCode, urlConnection.getResponseMessage());
}
urlConnection.disconnect(); // disconnect connection
} catch (IOException e) {
e.printStackTrace();
if (callback != null) {
// callback error
callback.OnError(500, e.getLocalizedMessage());
}
}
}
}).start(); // start thread
}
}

I see some other answers have given the alternative, I personally think that intuitively you're doing the right thing ;). Sorry, at devoxx where several speakers have been ranting about this sort of thing.
That's why I personally use Apache's HTTPClient/HttpCore libraries to do this sort of work, I find their API to be easier to use than Java's native HTTP support. YMMV of course!

GET and POST method set like this... Two types for api calling 1)get() and 2) post() . get() method to get value from api json array to get value & post() method use in our data post in url and get response.
public class HttpClientForExample {
private final String USER_AGENT = "Mozilla/5.0";
public static void main(String[] args) throws Exception {
HttpClientExample http = new HttpClientExample();
System.out.println("Testing 1 - Send Http GET request");
http.sendGet();
System.out.println("\nTesting 2 - Send Http POST request");
http.sendPost();
}
// HTTP GET request
private void sendGet() throws Exception {
String url = "http://www.google.com/search?q=developer";
HttpClient client = new DefaultHttpClient();
HttpGet request = new HttpGet(url);
// add request header
request.addHeader("User-Agent", USER_AGENT);
HttpResponse response = client.execute(request);
System.out.println("\nSending 'GET' request to URL : " + url);
System.out.println("Response Code : " +
response.getStatusLine().getStatusCode());
BufferedReader rd = new BufferedReader(
new InputStreamReader(response.getEntity().getContent()));
StringBuffer result = new StringBuffer();
String line = "";
while ((line = rd.readLine()) != null) {
result.append(line);
}
System.out.println(result.toString());
}
// HTTP POST request
private void sendPost() throws Exception {
String url = "https://selfsolve.apple.com/wcResults.do";
HttpClient client = new DefaultHttpClient();
HttpPost post = new HttpPost(url);
// add header
post.setHeader("User-Agent", USER_AGENT);
List<NameValuePair> urlParameters = new ArrayList<NameValuePair>();
urlParameters.add(new BasicNameValuePair("sn", "C02G8416DRJM"));
urlParameters.add(new BasicNameValuePair("cn", ""));
urlParameters.add(new BasicNameValuePair("locale", ""));
urlParameters.add(new BasicNameValuePair("caller", ""));
urlParameters.add(new BasicNameValuePair("num", "12345"));
post.setEntity(new UrlEncodedFormEntity(urlParameters));
HttpResponse response = client.execute(post);
System.out.println("\nSending 'POST' request to URL : " + url);
System.out.println("Post parameters : " + post.getEntity());
System.out.println("Response Code : " +
response.getStatusLine().getStatusCode());
BufferedReader rd = new BufferedReader(
new InputStreamReader(response.getEntity().getContent()));
StringBuffer result = new StringBuffer();
String line = "";
while ((line = rd.readLine()) != null) {
result.append(line);
}
System.out.println(result.toString());
}
}

I had the same issue. I wanted to send data via POST.
I used the following code:
URL url = new URL("http://example.com/getval.php");
Map<String,Object> params = new LinkedHashMap<>();
params.put("param1", param1);
params.put("param2", param2);
StringBuilder postData = new StringBuilder();
for (Map.Entry<String,Object> param : params.entrySet()) {
if (postData.length() != 0) postData.append('&');
postData.append(URLEncoder.encode(param.getKey(), "UTF-8"));
postData.append('=');
postData.append(URLEncoder.encode(String.valueOf(param.getValue()), "UTF-8"));
}
String urlParameters = postData.toString();
URLConnection conn = url.openConnection();
conn.setDoOutput(true);
OutputStreamWriter writer = new OutputStreamWriter(conn.getOutputStream());
writer.write(urlParameters);
writer.flush();
String result = "";
String line;
BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream()));
while ((line = reader.readLine()) != null) {
result += line;
}
writer.close();
reader.close()
System.out.println(result);
I used Jsoup for parse:
Document doc = Jsoup.parseBodyFragment(value);
Iterator<Element> opts = doc.select("option").iterator();
for (;opts.hasNext();) {
Element item = opts.next();
if (item.hasAttr("value")) {
System.out.println(item.attr("value"));
}
}

Try this pattern:
public static PricesResponse getResponse(EventRequestRaw request) {
// String urlParameters = "param1=a&param2=b&param3=c";
String urlParameters = Piping.serialize(request);
HttpURLConnection conn = RestClient.getPOSTConnection(endPoint, urlParameters);
PricesResponse response = null;
try {
// POST
OutputStreamWriter writer = new OutputStreamWriter(conn.getOutputStream());
writer.write(urlParameters);
writer.flush();
// RESPONSE
BufferedReader reader = new BufferedReader(new InputStreamReader((conn.getInputStream()), StandardCharsets.UTF_8));
String json = Buffering.getString(reader);
response = (PricesResponse) Piping.deserialize(json, PricesResponse.class);
writer.close();
reader.close();
} catch (Exception e) {
e.printStackTrace();
}
conn.disconnect();
System.out.println("PricesClient: " + response.toString());
return response;
}
public static HttpURLConnection getPOSTConnection(String endPoint, String urlParameters) {
return RestClient.getConnection(endPoint, "POST", urlParameters);
}
public static HttpURLConnection getConnection(String endPoint, String method, String urlParameters) {
System.out.println("ENDPOINT " + endPoint + " METHOD " + method);
HttpURLConnection conn = null;
try {
URL url = new URL(endPoint);
conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod(method);
conn.setDoOutput(true);
conn.setRequestProperty("Content-Type", "text/plain");
} catch (IOException e) {
e.printStackTrace();
}
return conn;
}

This answer covers the specific case of the POST Call using a Custom Java POJO.
Using maven dependency for Gson to serialize our Java Object to JSON.
Install Gson using the dependency below.
<dependency>
<groupId>com.google.code.gson</groupId>
<artifactId>gson</artifactId>
<version>2.8.5</version>
<scope>compile</scope>
</dependency>
For those using gradle can use the below
dependencies {
implementation 'com.google.code.gson:gson:2.8.5'
}
Other imports used:
import org.apache.http.HttpResponse;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.*;
import org.apache.http.impl.client.CloseableHttpClient;
import com.google.gson.Gson;
Now, we can go ahead and use the HttpPost provided by Apache
private CloseableHttpClient httpclient = HttpClients.createDefault();
HttpPost httppost = new HttpPost("https://example.com");
Product product = new Product(); //custom java object to be posted as Request Body
Gson gson = new Gson();
String client = gson.toJson(product);
httppost.setEntity(new StringEntity(client, ContentType.APPLICATION_JSON));
httppost.setHeader("RANDOM-HEADER", "headervalue");
//Execute and get the response.
HttpResponse response = null;
try {
response = httpclient.execute(httppost);
} catch (IOException e) {
throw new InternalServerErrorException("Post fails");
}
Response.Status responseStatus = Response.Status.fromStatusCode(response.getStatusLine().getStatusCode());
return Response.status(responseStatus).build();
The above code will return with the response code received from the POST Call

here i sent jsonobject as parameter //jsonobject={"name":"lucifer","pass":"abc"}//serverUrl = "http://192.168.100.12/testing" //host=192.168.100.12
public static String getJson(String serverUrl,String host,String jsonobject){
StringBuilder sb = new StringBuilder();
String http = serverUrl;
HttpURLConnection urlConnection = null;
try {
URL url = new URL(http);
urlConnection = (HttpURLConnection) url.openConnection();
urlConnection.setDoOutput(true);
urlConnection.setRequestMethod("POST");
urlConnection.setUseCaches(false);
urlConnection.setConnectTimeout(50000);
urlConnection.setReadTimeout(50000);
urlConnection.setRequestProperty("Content-Type", "application/json");
urlConnection.setRequestProperty("Host", host);
urlConnection.connect();
//You Can also Create JSONObject here
OutputStreamWriter out = new OutputStreamWriter(urlConnection.getOutputStream());
out.write(jsonobject);// here i sent the parameter
out.close();
int HttpResult = urlConnection.getResponseCode();
if (HttpResult == HttpURLConnection.HTTP_OK) {
BufferedReader br = new BufferedReader(new InputStreamReader(
urlConnection.getInputStream(), "utf-8"));
String line = null;
while ((line = br.readLine()) != null) {
sb.append(line + "\n");
}
br.close();
Log.e("new Test", "" + sb.toString());
return sb.toString();
} else {
Log.e(" ", "" + urlConnection.getResponseMessage());
}
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (JSONException e) {
e.printStackTrace();
} finally {
if (urlConnection != null)
urlConnection.disconnect();
}
return null;
}

Hello pls use this class to improve your post method
public static JSONObject doPostRequest(HashMap<String, String> data, String url) {
try {
RequestBody requestBody;
MultipartBuilder mBuilder = new MultipartBuilder().type(MultipartBuilder.FORM);
if (data != null) {
for (String key : data.keySet()) {
String value = data.get(key);
Utility.printLog("Key Values", key + "-----------------" + value);
mBuilder.addFormDataPart(key, value);
}
} else {
mBuilder.addFormDataPart("temp", "temp");
}
requestBody = mBuilder.build();
Request request = new Request.Builder()
.url(url)
.post(requestBody)
.build();
OkHttpClient client = new OkHttpClient();
Response response = client.newCall(request).execute();
String responseBody = response.body().string();
Utility.printLog("URL", url);
Utility.printLog("Response", responseBody);
return new JSONObject(responseBody);
} catch (UnknownHostException | UnsupportedEncodingException e) {
JSONObject jsonObject=new JSONObject();
try {
jsonObject.put("status","false");
jsonObject.put("message",e.getLocalizedMessage());
} catch (JSONException e1) {
e1.printStackTrace();
}
Log.e(TAG, "Error: " + e.getLocalizedMessage());
} catch (Exception e) {
e.printStackTrace();
JSONObject jsonObject=new JSONObject();
try {
jsonObject.put("status","false");
jsonObject.put("message",e.getLocalizedMessage());
} catch (JSONException e1) {
e1.printStackTrace();
}
Log.e(TAG, "Other Error: " + e.getLocalizedMessage());
}
return null;
}

I higly recomend http-request built on apache http api.
For your case you can see example:
private static final HttpRequest<String.class> HTTP_REQUEST =
HttpRequestBuilder.createPost("http://example.com/index.php", String.class)
.responseDeserializer(ResponseDeserializer.ignorableDeserializer())
.build();
public void sendRequest(String request){
String parameters = request.split("\\?")[1];
ResponseHandler<String> responseHandler =
HTTP_REQUEST.executeWithQuery(parameters);
System.out.println(responseHandler.getStatusCode());
System.out.println(responseHandler.get()); //prints response body
}
If you are not interested in the response body
private static final HttpRequest<?> HTTP_REQUEST =
HttpRequestBuilder.createPost("http://example.com/index.php").build();
public void sendRequest(String request){
ResponseHandler<String> responseHandler =
HTTP_REQUEST.executeWithQuery(parameters);
}
For general sending post request with http-request: Read the documentation and see my answers HTTP POST request with JSON String in JAVA, Sending HTTP POST Request In Java, HTTP POST using JSON in Java

I took Boann's answer and used it to create a more flexible query string builder that supports lists and arrays, just like php's http_build_query method:
public static byte[] httpBuildQueryString(Map<String, Object> postsData) throws UnsupportedEncodingException {
StringBuilder postData = new StringBuilder();
for (Map.Entry<String,Object> param : postsData.entrySet()) {
if (postData.length() != 0) postData.append('&');
Object value = param.getValue();
String key = param.getKey();
if(value instanceof Object[] || value instanceof List<?>)
{
int size = value instanceof Object[] ? ((Object[])value).length : ((List<?>)value).size();
for(int i = 0; i < size; i++)
{
Object val = value instanceof Object[] ? ((Object[])value)[i] : ((List<?>)value).get(i);
if(i>0) postData.append('&');
postData.append(URLEncoder.encode(key + "[" + i + "]", "UTF-8"));
postData.append('=');
postData.append(URLEncoder.encode(String.valueOf(val), "UTF-8"));
}
}
else
{
postData.append(URLEncoder.encode(key, "UTF-8"));
postData.append('=');
postData.append(URLEncoder.encode(String.valueOf(value), "UTF-8"));
}
}
return postData.toString().getBytes("UTF-8");
}

For those having trouble receiving the request on a php page using $_POST because you expect key-value pairs:
While all the answers where very helpful, I lacked some basic understanding on which string actually to post, since in the old apache HttpClient I used
new UrlEncodedFormEntity(nameValuePairs); (Java)
and then could use $_POST in php do get the key-value pairs.
To my understanding now one has build that string manually before posting. So the string needs to look like
val data = "key1=val1&key2=val2"
but instead just adding it to the url it is posted (in the header).
The alternative would be to use a json-string instead:
val data = "{\"key1\":\"val1\",\"key2\":\"val2\"}" // {"key1":"val1","key2":"val2"}
and pull it in php without $_POST:
$json_params = file_get_contents('php://input');
// echo_p("Data: $json_params");
$data = json_decode($json_params, true);
Here you find a sample code in Kotlin:
class TaskDownloadTest : AsyncTask<Void, Void, Void>() {
override fun doInBackground(vararg params: Void): Void? {
var urlConnection: HttpURLConnection? = null
try {
val postData = JsonObject()
postData.addProperty("key1", "val1")
postData.addProperty("key2", "val2")
// reformat json to key1=value1&key2=value2
// keeping json because I may change the php part to interpret json requests, could be a HashMap instead
val keys = postData.keySet()
var request = ""
keys.forEach { key ->
// Log.i("data", key)
request += "$key=${postData.get(key)}&"
}
request = request.replace("\"", "").removeSuffix("&")
val requestLength = request.toByteArray().size
// Warning in Android 9 you need to add a line in the application part of the manifest: android:usesCleartextTraffic="true"
// https://stackoverflow.com/questions/45940861/android-8-cleartext-http-traffic-not-permitted
val url = URL("http://10.0.2.2/getdata.php")
urlConnection = url.openConnection() as HttpURLConnection
// urlConnection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded") // apparently default
// Not sure what these are for, I do not use them
// urlConnection.setRequestProperty("Content-Type", "application/json")
// urlConnection.setRequestProperty("Key","Value")
urlConnection.readTimeout = 5000
urlConnection.connectTimeout = 5000
urlConnection.requestMethod = "POST"
urlConnection.doOutput = true
// urlConnection.doInput = true
urlConnection.useCaches = false
urlConnection.setFixedLengthStreamingMode(requestLength)
// urlConnection.setChunkedStreamingMode(0) // if you do not want to handle request length which is fine for small requests
val out = urlConnection.outputStream
val writer = BufferedWriter(
OutputStreamWriter(
out, "UTF-8"
)
)
writer.write(request)
// writer.write("{\"key1\":\"val1\",\"key2\":\"val2\"}") // {"key1":"val1","key2":"val2"} JsonFormat or just postData.toString() for $json_params=file_get_contents('php://input'); json_decode($json_params, true); in php
// writer.write("key1=val1&key2=val2") // key=value format for $_POST in php
writer.flush()
writer.close()
out.close()
val code = urlConnection.responseCode
if (code != 200) {
throw IOException("Invalid response from server: $code")
}
val rd = BufferedReader(
InputStreamReader(
urlConnection.inputStream
)
)
var line = rd.readLine()
while (line != null) {
Log.i("data", line)
line = rd.readLine()
}
} catch (e: Exception) {
e.printStackTrace()
} finally {
urlConnection?.disconnect()
}
return null
}
}

Now I had to do an HTTP request class, it is probably not the most efficient class, but it works.
I collected some codes from this page and made it more dynamic.
Anyone who needs a complete code, I attached it below.
For an example of how to use it, you can look at the main method.
Also, if you are willing to improve classes online, you are more than welcome to help me make this class better.
import java.net.*;
import java.util.*;
import java.nio.charset.*;
import java.io.*;
public class HttpRequest {
String result = "";
HttpRequest(String _url, String _method, Map<String, String> _postData, String _contentType) {
try {
URL url = new URL( _url );
URLConnection con = url.openConnection();
HttpURLConnection http = (HttpURLConnection)con;
http.setRequestMethod(_method); // PUT is another valid option
http.setDoOutput(true);
StringJoiner sj = new StringJoiner("&");
for(Map.Entry<String,String> entry : _postData.entrySet())
sj.add(URLEncoder.encode(entry.getKey(), "UTF-8") + "=" + entry.getValue());
//sj.add(URLEncoder.encode(entry.getKey(), "UTF-8") + "=" + URLEncoder.encode(entry.getValue()));
byte[] out = sj.toString().getBytes(StandardCharsets.UTF_8);
int length = out.length;
http.setFixedLengthStreamingMode(length);
http.setRequestProperty("Content-Type", _contentType);
http.setRequestProperty( "charset", "utf-8");
http.setRequestProperty( "Content-Length", Integer.toString( length ));
http.setInstanceFollowRedirects( false );
http.setUseCaches( false );
http.connect();
try(OutputStream os = http.getOutputStream()) {
os.write(out);
}
if (http.getResponseCode() == HttpURLConnection.HTTP_OK) {
try (BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(http.getInputStream()))) {
String line;
while ((line = bufferedReader.readLine()) != null) {
result = result + line;
}
}
} else {
System.out.println("Bad response!");
}
}catch (IOException e) {
// writing exception to log
e.printStackTrace();
}
}
HttpRequest(String _url, String _method, Map<String, String> _postData) {
this(_url, _method, _postData, "text/html");
}
HttpRequest(String _url, String _method) {
this(_url, _method, new HashMap<String, String>());
}
HttpRequest(String _url) {
this(_url, "GET");
}
public String toString() {
return result;
}
public static void main(String[] args) {
// TODO Auto-generated method stub
Map<String, String> postData = new HashMap<String, String>();
postData.putIfAbsent("email", "test#test.com");
postData.putIfAbsent("password", "test");
HttpRequest result = new HttpRequest("https://httpbin.org/anything", "POST", postData, "application/x-www-form-urlencoded");
System.out.println(result.toString());
}
}

Appears that you also have to callconnection.getOutputStream() "at least once" (as well as setDoOutput(true)) for it to treat it as a POST.
So the minimum required code is:
URL url = new URL(urlString);
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
//connection.setRequestMethod("POST"); this doesn't seem to do anything at all..so not useful
connection.setDoOutput(true); // set it to POST...not enough by itself however, also need the getOutputStream call...
connection.connect();
connection.getOutputStream().close();
You can even use "GET" style parameters in the urlString, surprisingly. Though that might confuse things.
You can also use NameValuePair apparently.