Post Request Send JSON Data Java Httpurlconnection

Post Json data with HttpURLConnection to REST API server

This is how I send a POST

Let me know if you need any clarification.

public static String executePost(String targetURL, String requestJSON, String apikey) {
        HttpURLConnection connection = null;
        InputStream is = null;

        try {
            //Create connection
            URL url = new URL(targetURL);
            connection = (HttpURLConnection) url.openConnection();
            connection.setRequestMethod("POST");
            connection.setRequestProperty("Content-Type", "application/json");
            //TODO may be prod or preprod api key
            if (apikey.equals(Constants.APIKEY_PREPROD)) {
                connection.setRequestProperty("Authorization", Constants.APIKEY_PREPROD);
            }
            if (apikey.equals(Constants.APIKEY_PROD)){
                connection.setRequestProperty("Authorization", Constants.APIKEY_PROD);
            }
            connection.setRequestProperty("Content-Length", Integer.toString(requestJSON.getBytes().length));
            connection.setRequestProperty("Content-Language", "en-US");  
            connection.setUseCaches(false);
            connection.setDoOutput(true);

            //Send request
            System.out.println(requestJSON);
            DataOutputStream wr = new DataOutputStream (
            connection.getOutputStream());
            wr.writeBytes(requestJSON);
            wr.close();

            //Get Response  

            try {
                is = connection.getInputStream();
            } catch (IOException ioe) {
                if (connection instanceof HttpURLConnection) {
                    HttpURLConnection httpConn = (HttpURLConnection) connection;
                    int statusCode = httpConn.getResponseCode();
                    if (statusCode != 200) {
                        is = httpConn.getErrorStream();
                    }
                }
            }

            BufferedReader rd = new BufferedReader(new InputStreamReader(is));

            StringBuilder response = new StringBuilder(); // or StringBuffer if Java version 5+
            String line;
            while ((line = rd.readLine()) != null) {
                response.append(line);
                response.append('\r');
            }
            rd.close();
            return response.toString();
        } catch (Exception e) {

            e.printStackTrace();
            return null;

        } finally {
            if (connection != null) {
                connection.disconnect();
            }
        }
    }

HttpUrlConnection with post request and parameter as JSON object?

I Found a solution for this by this steps

urlConnection = (HttpURLConnection) url
                        .openConnection();
                urlConnection.setDoOutput(true);
                urlConnection.setRequestMethod("POST");
                urlConnection.setRequestProperty("Content-Type", "application/json");
                urlConnection.setRequestProperty("x-api-key", x_api);
                urlConnection.setRequestProperty("Accept", "application/json");

                String datajson =  "{\"file\": \""+imageString.trim()+"\"}";
                Log.e("data","json:"+datajson);

                OutputStream os = urlConnection.getOutputStream();
                os.write(datajson.getBytes("UTF-8"));
                os.close();

How to send JSON data to API using HttpsURLConnection on Android?

Send the request:

String myData = "{\"username\":\"username\",\"password\":\"password\"}";
URL url = new URL ("https://api.url.com/api/token/");

HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod("POST");
conn.setRequestProperty("Content-Type", "application/json; utf-8");
conn.setRequestProperty("Accept", "application/json");
conn.setDoOutput(true);

try(OutputStream outputStream = conn.getOutputStream()) {
    byte[] input = myData.getBytes("utf-8");
    outputStream.write(input, 0, input.length);           
}

To read the response:

StringBuilder sb = new StringBuilder();
try(BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream(), "utf-8"))) {
    String line = null;
    while ((line = reader.readLine()) != null) {
        sb.append(line.trim());
    }
}
System.out.println(sb.toString());

I hope that helps!

How to send Json array as post params in android open URL connection

This sample for your reference

String request = "your Url Here";

URL url = new URL(request); 
HttpURLConnection connection = (HttpURLConnection) url.openConnection();   
connection.setDoOutput(true);
connection.setDoInput(true);
connection.setInstanceFollowRedirects(false); 
connection.setRequestMethod("POST"); 
conn.setRequestProperty("Accept", "application/json");
conn.setRequestProperty("Authorization", "Bearer Key");
conn.setRequestProperty("Content-Type", "application/json");

DataOutputStream wr = new DataOutputStream(connection.getOutputStream ());
wr.writeBytes(otherParametersUrServiceNeed);

JSONArray jsonArray=new JSONArray();
JSONObject jsonParam = new JSONObject();
jsonParam.put("ID", "25");
jsonParam.put("description", "Real");
jsonParam.put("enable", "true");
jsonArray.put(jsonParam);

wr.writeBytes(jsonArray.toString());

wr.flush();
wr.close();

For more detail checkout here, here or here

Can't send JSON in a Java HTTP POST request

Thanks to Andreas, it was just missing the line :

connection.setRequestProperty("Content-Type", "application/json");

It works fine now.

Get Json / Resonse body from Curl Post Request in Java

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.

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