Android, send string from app to web server

Question

I am trying to make an app where i am supposed to send data from the application to a web server. So far i've been searching and not been able to find a working example, i've found some using asynctask which does not work, so any help is appreciated!

Show us what you have tried till now, and then ask for help. Or else do bit of Googling first, as you will tons of links related to Client Server codes in Android. — Alok Nair
– Alok Nair, Commented Oct 29, 2014 at 11:26

duggu · Accepted Answer · 2014-10-29 11:23:49Z

try below code :-

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.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
import android.app.Activity;
import com.hmkcode.android.vo.Person;

public class MainActivity extends Activity implements OnClickListener {

    TextView tvIsConnected;
    EditText etName,etCountry,etTwitter;
    Button btnPost;

    Person person;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // get reference to the views
        tvIsConnected = (TextView) findViewById(R.id.tvIsConnected);
        etName = (EditText) findViewById(R.id.etName);
        etCountry = (EditText) findViewById(R.id.etCountry);
        etTwitter = (EditText) findViewById(R.id.etTwitter);
        btnPost = (Button) findViewById(R.id.btnPost);

        // check if you are connected or not
        if(isConnected()){
            tvIsConnected.setBackgroundColor(0xFF00CC00);
            tvIsConnected.setText("You are conncted");
        }
        else{
            tvIsConnected.setText("You are NOT conncted");
        }

        // add click listener to Button "POST"
        btnPost.setOnClickListener(this);

    }

    public static String POST(String url, Person person){
        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 = "";

            // 3. build jsonObject
            JSONObject jsonObject = new JSONObject();
            jsonObject.accumulate("name", person.getName());
            jsonObject.accumulate("country", person.getCountry());
            jsonObject.accumulate("twitter", person.getTwitter());

            // 4. convert JSONObject to JSON to String
            json = jsonObject.toString();

            // ** Alternative way to convert Person object to JSON string usin Jackson Lib 
            // ObjectMapper mapper = new ObjectMapper();
            // json = mapper.writeValueAsString(person); 

            // 5. set json to StringEntity
            StringEntity se = new StringEntity(json);

            // 6. set httpPost Entity
            httpPost.setEntity(se);

            // 7. Set some headers to inform server about the type of the content   
            httpPost.setHeader("Accept", "application/json");
            httpPost.setHeader("Content-type", "application/json");

            // 8. Execute POST request to the given URL
            HttpResponse httpResponse = httpclient.execute(httpPost);

            // 9. receive response as inputStream
            inputStream = httpResponse.getEntity().getContent();

            // 10. convert inputstream to string
            if(inputStream != null)
                result = convertInputStreamToString(inputStream);
            else
                result = "Did not work!";

        } catch (Exception e) {
            Log.d("InputStream", e.getLocalizedMessage());
        }

        // 11. return result
        return result;
    }

    public boolean isConnected(){
        ConnectivityManager connMgr = (ConnectivityManager) getSystemService(Activity.CONNECTIVITY_SERVICE);
            NetworkInfo networkInfo = connMgr.getActiveNetworkInfo();
            if (networkInfo != null && networkInfo.isConnected()) 
                return true;
            else
                return false;    
    }
    @Override
    public void onClick(View view) {

        switch(view.getId()){
            case R.id.btnPost:
                if(!validate())
                    Toast.makeText(getBaseContext(), "Enter some data!", Toast.LENGTH_LONG).show();
                // call AsynTask to perform network operation on separate thread
                new HttpAsyncTask().execute("http://hmkcode.appspot.com/jsonservlet");
            break;
        }

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

            person = new Person();
            person.setName(etName.getText().toString());
            person.setCountry(etCountry.getText().toString());
            person.setTwitter(etTwitter.getText().toString());

            return POST(urls[0],person);
        }
        // onPostExecute displays the results of the AsyncTask.
        @Override
        protected void onPostExecute(String result) {
            Toast.makeText(getBaseContext(), "Data Sent!", Toast.LENGTH_LONG).show();
       }
    }

    private boolean validate(){
        if(etName.getText().toString().trim().equals(""))
            return false;
        else if(etCountry.getText().toString().trim().equals(""))
            return false;
        else if(etTwitter.getText().toString().trim().equals(""))
            return false;
        else
            return true;    
    }
    private static String convertInputStreamToString(InputStream inputStream) throws IOException{
        BufferedReader bufferedReader = new BufferedReader( new InputStreamReader(inputStream));
        String line = "";
        String result = "";
        while((line = bufferedReader.readLine()) != null)
            result += line;

        inputStream.close();
        return result;

    }   
}

see below link for more info :-

http://hmkcode.com/android-send-json-data-to-server/

http://androidexample.com/How_To_Make_HTTP_POST_Request_To_Server_-_Android_Example/index.php?view=article_discription&aid=64&aaid=89

Punith K · Accepted Answer · 2014-10-29 11:41:07Z

Try this,

import java.util.ArrayList;
import java.util.List;

import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.HttpClient;
import org.apache.http.client.ResponseHandler;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.BasicResponseHandler;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicNameValuePair;

import android.app.Activity;
import android.app.AlertDialog;
import android.app.ProgressDialog;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.SharedPreferences;
import android.content.SharedPreferences.Editor;
import android.os.AsyncTask;
import android.os.Bundle;
import android.preference.PreferenceManager;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.EditText;
import android.widget.Toast;

public class AdminLogin extends Activity {

    EditText adminUN, adminPass;
    CheckBox cb;
    Button loginBtn;
    HttpPost httppost;
    StringBuffer buffer;
    HttpResponse response;
    HttpClient httpclient;
    List<NameValuePair> nameValuePairs;

   // Your IP address or your website complete address
    String adminLoginURL = "http://192.168.1.1/admin_login.php";
    ProgressDialog dialog = null;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);

        setContentView(R.layout.admin_login);

        loginBtn = (Button) findViewById(R.id.adminLogin);
        adminUN = (EditText) findViewById(R.id.adminUName);
        adminPass = (EditText) findViewById(R.id.adminPass);

        loginBtn.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {

                new Admin_Login().execute();

            }
        });
    }

    class Admin_Login extends AsyncTask<String, String, String> {
        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            dialog = new ProgressDialog(AdminLogin.this);
            dialog.setMessage("Please Wait..!");
            dialog.setIndeterminate(false);
            dialog.setCancelable(true);
            dialog.show();
        }

        protected String doInBackground(String... params) {

            new Thread(new Runnable() {
                public void run() {
                    login();
                }
            }).start();

            return null;
        }

        protected void onPostExecute(String file_url) {
            // dismiss the dialog once got all details
            dialog.dismiss();
        }

    }

    void login() {
        try {

            httpclient = new DefaultHttpClient();
            httppost = new HttpPost(adminLoginURL);

            // add your data
            nameValuePairs = new ArrayList<NameValuePair>(2);
            nameValuePairs.add(new BasicNameValuePair("username", adminUN
                    .getText().toString().trim()));
            nameValuePairs.add(new BasicNameValuePair("password", adminPass
                    .getText().toString().trim()));
            httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
            // Execute HTTP Post Request
            response = httpclient.execute(httppost);

            ResponseHandler<String> responseHandler = new BasicResponseHandler();
            final String response = httpclient.execute(httppost,
                    responseHandler);

            boolean matches = response.startsWith("User Found");
            if (matches) {
                // Do something start an Activity or do anything you wanted
                }
            } else {
                showAlert();
            }

        } catch (Exception e) {
            dialog.dismiss();
            System.out.println("Exception : " + e.getMessage());
        }
    }

    public void showAlert() {
        AdminLogin.this.runOnUiThread(new Runnable() {
            public void run() {
                AlertDialog.Builder builder = new AlertDialog.Builder(
                        AdminLogin.this);
                builder.setTitle("Login Error.");
                builder.setMessage("User not Found.")
                        .setCancelable(false)
                        .setPositiveButton("OK",
                                new DialogInterface.OnClickListener() {
                                    public void onClick(DialogInterface dialog,
                                            int id) {
                                    }
                                });
                AlertDialog alert = builder.create();
                alert.show();
            }
        });

    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu items for use in the action bar
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.main_exit, menu);
        return super.onCreateOptionsMenu(menu);
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle presses on the action bar items
        switch (item.getItemId()) {
        case R.id.action_exit:
            finish();
            return true;
        default:
            return super.onOptionsItemSelected(item);
        }
    }   
}

Create an .xml file to get the username, password, and login button

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@drawable/ic_wall"
    android:gravity="center_horizontal"
    android:orientation="vertical" >

    <EditText
        android:id="@+id/adminUName"
        android:layout_width="250dp"
        android:layout_height="wrap_content"
        android:layout_marginTop="50dip"
        android:hint="Username"
        android:singleLine="true" />

    <requestFocus />

    <EditText
        android:id="@+id/adminPass"
        android:layout_width="250dp"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dip"
        android:ems="10"
        android:hint="Password"
        android:inputType="textPassword"
        android:singleLine="true" />

    <Button
        android:id="@+id/adminLogin"
        android:layout_width="150dp"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:layout_marginTop="20dip"
        android:text="Login"
        android:textColor="#0b84aa" />

</LinearLayout>

You must have PhpMyAdmin to try this in local system, if you have hosted server part then try use the following php code and run it.

adminLogin.php 

<?php
$hostname_localhost ="";
$database_localhost ="";
$username_localhost ="";
$password_localhost ="";
# Make sure above fields are filled with your config values (must)
$localhost = mysql_connect($hostname_localhost,$username_localhost,$password_localhost)
or
trigger_error(mysql_error(),E_USER_ERROR);

mysql_select_db($database_localhost, $localhost);


if (empty($_POST['username'])) { 
        echo "Please Enter a name"; 
    } else {
        $username = $_POST['username']; 
    }
    if (empty($_POST['password'])) {
     echo "Please Enter Your Password ";
    } else {
        $password = SHA1($_POST['password']);
    }



$query_search = "select * from adminregister where username = '".$username."' AND password = '".$password."'";
$query_exec = mysql_query($query_search) or die(mysql_error());
$rows = mysql_num_rows($query_exec);
//echo $rows;
 if($rows == 0) {
 echo "\nNo Such User Found";
 }
 else  {

    echo "User Found";
}
mysql_close();
?>

Note: You need to create database and table specified in mysql to feed and retrieve the data

If any errors please leave a comment.

Please consider including some information about your answer, rather than simply posting code. We try to provide not just 'fixes', but help people learn. You should explain what was wrong in the original code, what you did differently, and why your change(s) worked.

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