Http Post Request

Question

i am developing an android app, which needs to send a string to web server(written in java).when server receives this string it will automatically fire response.after going through many examples i tried to do this . i used following code to send request.

try{
                String url = "https://mywebserver";
                URL obj = new URL(url);
                HttpsURLConnection con = (HttpsURLConnection) obj.openConnection();

                //add reuqest header
                con.setRequestMethod("POST");

                con.setRequestProperty("Accept-Language", "en-US,en;q=0.5");

                String urlParameters = "014500000000000000000000**  0000      0030000100700006800006000000000000000 0     I   00000000        00000000000000000000000000000000000073054721143";

                // Send post request
                con.setDoOutput(true);


                //something is wrong after this line
                DataOutputStream wr = new DataOutputStream(con.getOutputStream());
                wr.writeBytes(urlParameters);
                wr.flush();
                wr.close();

                int responseCode = con.getResponseCode();


                BufferedReader in = new BufferedReader(new InputStreamReader(con.getInputStream()));
                String inputLine;
                StringBuffer response = new StringBuffer();

                while ((inputLine = in.readLine()) != null) {
                    response.append(inputLine);
                }
                in.close();

                //print result
                System.out.println(response.toString());

            }catch(Exception e){
                tv_str.setText("caught exception");
            }

this is not working (generating an exception). and i also tried this example- answer 2 but not working and also, is there any webserver for Testing http post requests. ie how do i test my request

if there is any other way to do this please tell me as i am new to this

my logcat:

07-08 11:59:37.423: D/dalvikvm(31971): Late-enabling CheckJNI
07-08 11:59:37.713: I/Adreno-EGL(31971): <qeglDrvAPI_eglInitialize:316>: EGL 1.4 QUALCOMM build:  (CL4169980)
07-08 11:59:37.713: I/Adreno-EGL(31971): OpenGL ES Shader Compiler Version: 17.01.10.SPL
07-08 11:59:37.713: I/Adreno-EGL(31971): Build Date: 12/04/13 Wed
07-08 11:59:37.713: I/Adreno-EGL(31971): Local Branch: workspace
07-08 11:59:37.713: I/Adreno-EGL(31971): Remote Branch: 
07-08 11:59:37.713: I/Adreno-EGL(31971): Local Patches: 
07-08 11:59:37.713: I/Adreno-EGL(31971): Reconstruct Branch: 
07-08 11:59:37.764: D/OpenGLRenderer(31971): Enabling debug mode 0
07-08 11:59:37.849: E/Adreno-ES20(31971): <gl_external_unsized_fmt_to_sized:2379>: QCOM> format, datatype mismatch
07-08 11:59:37.849: E/Adreno-ES20(31971): <get_texture_formats:3009>: QCOM> Invalid format!

thanks in advance

Answer 1

yes json is easy. i implemented this and its working fine.. thanks to JLONG and user1369434.

package m.example.postrwq;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;

import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONObject;

import android.support.v7.app.ActionBarActivity;
import android.app.Activity;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends ActionBarActivity {
    Button btnPost;
    TextView tvIsConnected;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        btnPost = (Button) findViewById(R.id.button1);
        tvIsConnected = (TextView) findViewById(R.id.textView1);

        if(isConnected()){
            tvIsConnected.setBackgroundColor(0xFF00CC00);
            tvIsConnected.setText("You are conncted");
        }
        else{
            tvIsConnected.setText("You are NOT conncted");
        }
    btnPost.setOnClickListener(new OnClickListener(){

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
            new HttpAsyncTask().execute("http://hmkcode.appspot.com/jsonservlet");
        }});


    }
     private class HttpAsyncTask extends AsyncTask<String, Void, String> {
        @Override
        protected String doInBackground(String... urls) {



            return POST(urls[0]);
        }
        // onPostExecute displays the results of the AsyncTask.
        @Override
        protected void onPostExecute(String result) {
            Toast.makeText(getBaseContext(), "Data Sent!", Toast.LENGTH_LONG).show();
       }
    }
public static String POST(String url){
    InputStream inputStream = null;
    String result = "";
    try {

        // 1. create HttpClient
        HttpClient httpclient = new DefaultHttpClient();

        // 2. make POST request to the given URL
        HttpPost httpPost = new HttpPost(url);

        String json = "my string";




     // 6. set json to StringEntity
        StringEntity se = new StringEntity(json);

        // 7. set httpPost Entity
        httpPost.setEntity(se);

        // 8. Set some headers to inform server about the type of the content   
        httpPost.setHeader("Accept", "application/json");
        httpPost.setHeader("Content-type", "application/json");

        // 9. Execute POST request to the given URL
        HttpResponse httpResponse = httpclient.execute(httpPost);

        // 10. receive response as inputStream
        inputStream = httpResponse.getEntity().getContent();

        // 11. convert inputstream to string
        if(inputStream != null)
            result = convertInputStreamToString(inputStream);
        else
            result = "Did not work!";

    } catch (Exception e) {
        Log.d("InputStream", e.getLocalizedMessage());
    }
 // 12. return result
    return result;

}

private static String convertInputStreamToString(InputStream inputStream) throws IOException {
    // TODO Auto-generated method stub

    BufferedReader bufferedReader = new BufferedReader( new InputStreamReader(inputStream));
    String line = "";
    String result = "";
    while((line = bufferedReader.readLine()) != null)
        result += line;

    inputStream.close();
    return result;

}
public boolean isConnected() {
    // TODO Auto-generated method stub
     ConnectivityManager connMgr = (ConnectivityManager) getSystemService(Activity.CONNECTIVITY_SERVICE);
     NetworkInfo networkInfo = connMgr.getActiveNetworkInfo();
     if (networkInfo != null && networkInfo.isConnected()) 
         return true;
     else
         return false;  
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {

    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();
    if (id == R.id.action_settings) {
        return true;
    }
    return super.onOptionsItemSelected(item);
  }


}

hope this will help others

Answer 2

Do you really need to use HTTPS ? If yes I guess you should set SSLSocketFactory for your connection after opening it. Check this answer for more info: https://stackoverflow.com/a/16507195/1407451

I also would like to recomend you not use HttpsURLConnection itself but take look at some libraries for network comunications like Retrofit or Volley . For me it seems to be much easer to use.

Answer 3

只是一个提示：我认为将JSON与GSON（而不是简单的String）结合使用会更容易在应用程序和Web服务器之间传输数据。

Answer 4

I use a JSON parser java class, because it is much easier to transport data from the app and server just like user1369434 said. I forgot where I got the code but here it is, create a java class named JSONparser then post this:

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.util.List;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.client.utils.URLEncodedUtils;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONException;
import org.json.JSONObject;

import android.util.Log;

public class JSONParser {

    static InputStream is = null;
    static JSONObject jObj = null;
    static String json = "";

    // constructor
    public JSONParser() {

    }

    // function get json from url
    // by making HTTP POST or GET mehtod
    public JSONObject makeHttpRequest(String url, String method,
            List<NameValuePair> params) {

        // Making HTTP request
        try {

            // check for request method
            if(method == "POST"){
                // request method is POST
                // defaultHttpClient
                DefaultHttpClient httpClient = new DefaultHttpClient();
                HttpPost httpPost = new HttpPost(url);
                httpPost.setEntity(new UrlEncodedFormEntity(params));

                HttpResponse httpResponse = httpClient.execute(httpPost);
                HttpEntity httpEntity = httpResponse.getEntity();
                is = httpEntity.getContent();

            }else if(method == "GET"){
                // request method is GET
                DefaultHttpClient httpClient = new DefaultHttpClient();
                String paramString = URLEncodedUtils.format(params, "utf-8");
                url += "?" + paramString;
                HttpGet httpGet = new HttpGet(url);

                HttpResponse httpResponse = httpClient.execute(httpGet);
                HttpEntity httpEntity = httpResponse.getEntity();
                is = httpEntity.getContent();
            }           


        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

        try {
            BufferedReader reader = new BufferedReader(new InputStreamReader(
                    is, "iso-8859-1"), 8);
            StringBuilder sb = new StringBuilder();
            String line = null;
            while ((line = reader.readLine()) != null) {
                sb.append(line + "\n");
            }
            is.close();
            json = sb.toString();
        } catch (Exception e) {
            Log.e("Buffer Error", "Error converting result " + e.toString());
        }

        // try parse the string to a JSON object
        try {
            jObj = new JSONObject(json);
        } catch (JSONException e) {
            Log.e("JSON Parser", "Error parsing data " + e.toString());
        }

        // return JSON String
        return jObj;

    }
}

Then on your Activty do this:

    public class YOUR ACTIVITY extends Activity {

        JSONParser jParser = new JSONParser();

        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);

            //Create a Asynctask for the http request
            new NAMEOFYOURASYNCTASK().execute();

}

    }

and on your asynctask:

class YOURASYNCTASK extends AsyncTask<String, String, String> {

@Override
protected String doInBackground(String... args) {
    // TODO Auto-generated method stub
    // Building Parameters
    List<NameValuePair> params = new ArrayList<NameValuePair>();
    params.add(new BasicNameValuePair("username_GET", dealer_user_name ));

    // getting JSON string from URL
    json = jParser.makeHttpRequest(YOUR URL HERE, "POST", params);

    // Check your log cat for JSON reponse
    Log.d("All Products: ", json.toString());

modify your php code to throw JSON files back to the app and. like this:

    // array for JSON response
    $response = array();
    // success
    $response["success"] = 1;
    // echoing JSON response
    echo json_encode($response);

you get the idea. this is just a suggestion btw.