Question

Im trying to send some parameters from a simple android app using AsyncTask<>
through a get request ,but when i get the parameters on the servlet those are null!
And i cant understand why… , logcat doesnt show any errors so i cant find why..
here is my main activity :

package com.theopentutorials.android;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLConnection;
import android.app.Activity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

//the main activity
public class HttpGetServletActivity extends Activity implements OnClickListener {
Button button; // gui part
TextView outputText;
EditText titulli;
EditText ingredientet;
EditText receta;

public static String getTitulliS() {
    return titulliS;
}

// setters and getters of the url parameters
public static void setTitulliS(String titulliS) {
    HttpGetServletActivity.titulliS = titulliS;
}

public static String getIngredientetS() {
    return ingredientetS;
}

public static void setIngredientetS(String ingredientetS) {
    HttpGetServletActivity.ingredientetS = ingredientetS;
}

public static String getRecetaS() {
    return recetaS;
}

public static void setRecetaS(String recetaS) {
    HttpGetServletActivity.recetaS = recetaS;
}

public static String getURL() {
    return URL;
}

public static void setURL(String uRL) {
    URL = uRL;
}

// the parameters i would like to send
static String titulliS;
static String ingredientetS;
static String recetaS;
static String URL = "http://10.0.2.2:8080/HttpGetServlet/HelloWorldServlet?"
        + getTitulliS() + getIngredientetS() + getRecetaS();

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    findViewsById();

    button.setOnClickListener(this);
}

private void findViewsById() {
    button = (Button) findViewById(R.id.button);
    outputText = (TextView) findViewById(R.id.outputTxt);
    titulli = (EditText) findViewById(R.id.editText1);
    ingredientet = (EditText) findViewById(R.id.editText2);
    receta = (EditText) findViewById(R.id.editText2);
    setTitulliS("titulli=" + titulli.getText().toString() + "&");
    setIngredientetS("ingredientet=" + ingredientet.getText().toString()
            + "&");
    setRecetaS("receta=" + receta.getText().toString());

}

public void onClick(View view) {

    GetXMLTask task = new GetXMLTask();
    task.execute(new String[] { URL });
}

private class GetXMLTask extends AsyncTask<String, Void, String> {
    @Override
    protected String doInBackground(String... urls) {
        String output = null;
        for (String url : urls) {
            output = getOutputFromUrl(url);
        }
        return output;
    }

    private String getOutputFromUrl(String url) {
        StringBuffer output = new StringBuffer("");
        try {
            InputStream stream = getHttpConnection(url);
            BufferedReader buffer = new BufferedReader(
                    new InputStreamReader(stream));
            String s = "";
            while ((s = buffer.readLine()) != null)
                output.append(s);
        } catch (IOException e1) {
            e1.printStackTrace();
        }
        return output.toString();
    }

    // Makes HttpURLConnection and returns InputStream
    private InputStream getHttpConnection(String urlString)
            throws IOException {
        InputStream stream = null;
        URL url = new URL(urlString);
        URLConnection connection = url.openConnection();

        try {
            HttpURLConnection httpConnection = (HttpURLConnection) connection;
            httpConnection.setRequestMethod("GET");
            httpConnection.connect();

            if (httpConnection.getResponseCode() == HttpURLConnection.HTTP_OK) {
                stream = httpConnection.getInputStream();
            }
        } catch (Exception ex) {
            ex.printStackTrace();
        }
        return stream;
    }

    @Override
    protected void onPostExecute(String output) {
        outputText.setText(output);
    }
}
}

and here is my simple servlet :

import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
@WebServlet("/HelloWorldServlet")
public class HelloWorldServlet extends HttpServlet {
private static final long serialVersionUID = 1L;

public HelloWorldServlet() {
    super();
}

protected void doGet(HttpServletRequest request,
        HttpServletResponse response) throws ServletException, IOException {
       String titulli =  request.getParameter("titulli");
      String ingredientet =  request.getParameter("ingredientet");
       String receta =  request.getParameter("receta");
        PrintWriter out = response.getWriter();
        out.println(titulli+ingredientet+receta);
        System.out.println(titulli+ingredientet+receta);
}
}

Does somebody have any idea?Thank you in advance !

Answer 1

To me, it looks as if you are setting up the parameter extension for the input fields only in onCreate(), when you would really have to do this in onClick() for example.

I’d have a few other remarks along the lines of “why static?” etc but you didn’t ask for that. 😉