Java - sending HTTP parameters via POST method easily

Question

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 GETor 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

Comments

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Answer 1

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 );
}

Answer 2

Try this it worked fine

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();

    }

}

Answer 3

    HashMap<String, String> whaturl = new HashMap<String, String>();
    whaturl.put("email","me@abc.com");
    whaturl.put("password","XXXXX");
    String link1 = "http://www.abc.com";
    HttpUtility.newRequest(link1,HttpUtility.METHOD_POST,whaturl, new HttpUtility.Callback() {
        @Override
        public void OnSuccess(String response) {
           System.out.println("Server OnSuccess response="+response);
        }
        @Override
        public void OnError(int status_code, String message) {
              System.out.println("Server OnError status_code="+status_code+" message="+message);
        }
    });

Answer 4

This can also be a good substitute

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;
}

Answer 5

Use http-request built on apache http api.

Answer 6

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;
}

Answer 7

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);
}

Use this function

Answer 8

Use this function i works fine.

private static final HttpRequest<String.class> HTTPREQUEST = 
      HttpRequestBuilder.createPost("http://abc.com/home.php", String.class)
           .responseDeserializer(ResponseDeserializer.ignorableDeserializer())
           .build();
public void sendRequest(String request){
     String param = request.split("\\?")[1];
     ResponseHandler<String> responseHandler = 
            HTTP_REQUEST.executeWithQuery(parameters);
   System.out.println(responseHandler.getStatusCode());
   System.out.println(responseHandler.get()); //prints response body
}

Answer 9

A very small implementation and it works fine

import java.net.*;
public class Demo{
  public static void main(){
       String link = "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();
    }
}

Answer 10

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.

Answer 11

You can write like this simply get request in java code 

public static Integer sendOTP(String phone, String msg){ 

       String url = "http://example.php?user=xxx&password=sss!@&mobile="+phone+"&message="+ msg+"&sender=vxbxb&type=x";

        try {

            URL obj = new URL(url);

            HttpURLConnection con = (HttpURLConnection) obj.openConnection();

            con.getResponseCode();

            return 200;

            } catch (Exception e) {

                e.printStackTrace();

        }

}

Answer 12

Below are the steps we need to follow for sending Java HTTP requests using HttpURLConnection class.

1. Create URL object from the GET/POST URL String.
2. Call openConnection() method on URL object that returns instance of HttpURLConnection
3. Set the request method in HttpURLConnection instance, default value is GET.
4. Call setRequestProperty() method on HttpURLConnection instance to set request header values, such as “User-Agent” and “Accept-Language” etc.
5. We can call getResponseCode() to get the response HTTP code. This way we know if the request was processed successfully or there was any HTTP error message thrown.
6. For GET, we can simply use Reader and InputStream to read the response and process it accordingly.
7. For POST, before we read response we need to get the OutputStream from