Cannot authentication

Question

At this time, I want user to enter his/her username and password(Data is mocked @MySQL) But it does not work.

My file.php :

<?php
    include("ConnectDatabase.php");
    $Username = $_POST['Username'];
    $Password = $_POST['Password'];

    $q = mysql_query("SELECT Username, Password FROM Users
                    where Username = '".$Username."' and
                    Password = '".$Password."'");

    if(mysql_num_rows($q) > 0){
        print json_encode($q);
    }else{
        print "1";
    }
     mysql_close();
   ?>

My java file :

public class Authentication extends Activity implements OnClickListener,
        OnKeyListener, OnCheckedChangeListener {

    /** Called when the activity is first created. */

    ArrayList<NameValuePair> authentication;
    String passIn, userIn, result;
    EditText username, password;
    CheckBox remember;
    Button b_login;
    InputMethodManager inputManager;
    InputStream is;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        // userIn = username.getText().toString();
        // passIn = password.getText().toString();
        username = (EditText) findViewById(R.id.usrname);
        password = (EditText) findViewById(R.id.password);
        inputManager = (InputMethodManager) getSystemService(Context.INPUT_METHOD_SERVICE);
        remember = (CheckBox) findViewById(R.id.remember);
        remember.setOnCheckedChangeListener(this);
        b_login = (Button) findViewById(R.id.login);
        b_login.setOnClickListener(this);
        username = (EditText) findViewById(R.id.usrname);
        username.setOnKeyListener(this);
        password = (EditText) findViewById(R.id.password);
        password.setOnKeyListener(this);

    }

    public void onClick(View v) {
        // TODO Auto-generated method stub
        switch (v.getId()) {
        case R.id.login:
            while (true) {
                userIn = username.getText().toString();
                passIn = password.getText().toString();
                try {
                    sendAuthenticationData(userIn, passIn);
                    break;
                } catch (ClientProtocolException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                } catch (WrongInputException e) {
                    Toast.makeText(Authentication.this, "Invalid username or password", Toast.LENGTH_LONG);

                }
//              break;
            }
            Intent intent = new Intent(this, ApplicationMenus.class);
            this.startActivity(intent);
            clearText(username,password);

            break;
        }
    }

    public boolean onKey(View v, int keyCode, KeyEvent event) {
        // TODO Auto-generated method stub
        if ((event.getAction() == KeyEvent.ACTION_DOWN)
                && (keyCode == KeyEvent.KEYCODE_ENTER)) {
            // Perform action on key press

            inputManager.hideSoftInputFromWindow(v.getWindowToken(), 0);
            return true;
        }
        return false;
    }


    public void clearText(EditText usr, EditText pass) {
        usr.setText("");
        pass.setText("");
    }

    public void sendAuthenticationData(String username, String password)
            throws ClientProtocolException, IOException, WrongInputException {

        authentication = new ArrayList<NameValuePair>();
        authentication.add(new BasicNameValuePair("Username", userIn));
        authentication.add(new BasicNameValuePair("Password", passIn));
        this.sendData(authentication);
    }

    public void sendData(ArrayList<NameValuePair> data)
            throws ClientProtocolException, IOException, WrongInputException {

        HttpClient httpclient = new DefaultHttpClient();
        HttpPost httppost = new HttpPost(
                "path/Authentication.php"); // I use real path here
        httppost.setEntity(new UrlEncodedFormEntity(data));
        HttpResponse response = httpclient.execute(httppost);
        HttpEntity entity = response.getEntity();
//      is = entity.getContent();
        String temp = EntityUtils.toString(entity);

        if (temp.equals("1")) {
            throw new WrongInputException();
        }

    }}

This is my first time to write code that connect with PHP server, and JSON. I pretty confuse with JSON a lot, though I tried to follow many samples. Appreciate for any help

And what's the question? Also, did you get any error? Does your app crash? If so, can you paste the logcat trace? — Cristian, Jul 03 '11 at 16:49
I just don't know why it doesn't work. I didn't get any error. — Yoo, Jul 03 '11 at 16:55
look into PDO's prepared statements because your code is NOT safe => http://net.tutsplus.com/tutorials/php/why-you-should-be-using-phps-pdo-for-database-access/ — Alfred, Jul 03 '11 at 16:58
`where Username = '".$Username."' and Password = '".$Password."'");` indicates two major security flaws: SQL Injection, and stored plain text passwords. Please read up on http://stackoverflow.com/questions/601300/what-is-sql-injection and http://stackoverflow.com/questions/568657/is-it-ever-ok-to-store-password-in-plain-text-in-a-php-variable-or-php-constant . These problems are more serious than the JSON problem that you're trying to deal with. — Mike Samuel, Jul 03 '11 at 16:59

score 2 · Accepted Answer · answered Jul 03 '11 at 16:56

The first thing you forgot is mysql_real_escape_string for the incoming variables:

$Username = $_POST['Username'];

And your second problem is likely this:

   if (mysql_num_rows($q) > 0) {
        print json_encode($q);

The $q variable is a mysql_ result handle. It cannot be JSON-represented. You probably wanted to use:

        print json_encode(mysql_fetch_assoc($q));

So you'll get at least a result array/object with username/password there. Maybe it would be easier if you just send another simple numeric result back - print "2"; or something.

Also have you checked if you run PHP 5.2 or later, so that json_encode is certainly available?

Cannot authentication

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