Logging into a website using Android app (Java)

Question

I am currently trying to make an app that would allow you to log into your account and view whatever data needs to be displayed.

I am not using webview but instead,

Answer 1

Here is the solution to this:

class HTTPRequest implements Runnable {

    private URL url;
    private User user;
    private Handler handler;
    private String cookie;

    //**REDEFINED CONSTRUCTOR
    HTTPRequest(Handler in_handler, User in_user) {
        try {
                        url = new URL("https://yoururl.com");

            handler = in_handler;
            user = in_user;
        } catch (MalformedURLException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void run() {
        try {
            //**Preparing to open connection
            //**Using POST method
            //**Enabling Input & Output
            HttpsURLConnection conn = (HttpsURLConnection) url.openConnection();
            conn.setRequestMethod("POST");
            conn.setDoInput(true);
            conn.setDoOutput(true);

            //**Setting Headers to send with POST request
            conn.setRequestProperty("Accept", "text/html");
            conn.setRequestProperty("Accept", "text/xml");
            conn.setRequestProperty("Cookie", "upassword=" + user.getPasswordHashed() + "; ulogin=" + user.getUsername());
            conn.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
            conn.setRequestProperty("charset", "UTF-8");
            conn.setRequestProperty("User-Agent", "Mozilla/5.0");

            //**READING RESPONSE FROM THE SERVER:
            //**IF LOGIN WAS SUCCESSFUL, SEND MESSAGE WITH XML DATA BACK TO UI THREAD, ELSE SEND NULL TO UI THREAD
            BufferedReader input = new BufferedReader(new InputStreamReader(conn.getInputStream()));

            if (isLoginSuccess(input)) {
                StringBuilder response = new StringBuilder();
                String tempString;
                while ((tempString = input.readLine()) != null) {
                    response.append(tempString);
                }
                input.close();
                conn.disconnect();

                Message msg = Message.obtain();
                msg.obj = response.toString();
                handler.sendMessage(msg);
            } else if (!isLoginSuccess(input)) {
                input.close();
                conn.disconnect();
                Message msg = Message.obtain();
                msg.obj = "Wrong";
                handler.sendMessage(msg);
            }

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

    //**LOGIN IS SUCCESSFUL WHEN THE RESPONSE'S FIRST LINE EQUALS XML DECLARATION
    //**RETURNS TRUE IF THAT IS THE CASE, MEANING YOU HAVE SUCCESSFULLY LOGGED IN
    private boolean isLoginSuccess(BufferedReader input) throws IOException {
        String LoginSuccess = "";

        String response = input.readLine();
        return response.equals(LoginSuccess);
    }
}

MainActivity.java:

public class MainActivity extends AppCompatActivity {

    public static final String EXTRA_MESSAGE = "Message 1";
    public static final String EXTRA_MESSAGE_2 = "Message 2";
    Handler mainHandler;
    Thread thread;
    User user;

    EditText etUsername;
    EditText etPassword;
    CheckBox cbRememberMe;
    Button btLogin;

    SharedPreferences preferences;
    SharedPreferences.Editor SPEditor;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setTheme(R.style.LoginPageTheme);
        setContentView(R.layout.activity_main);

        //**DECLARATION OF SHARED PREFERENCES
        preferences = getApplicationContext().getSharedPreferences("Preferences", MODE_PRIVATE);
        SPEditor = preferences.edit();
        SPEditor.apply();

        //**HANDLER INSTANTIATING AND HANDLING MESSAGES FROM HTTPRequest
        mainHandler = new Handler(Looper.getMainLooper()) {
            @Override
            public void handleMessage(@NonNull Message msg) {
                String message = msg.obj.toString();
                thread.interrupt();
                if (!message.equals("Wrong")) {
                    if (cbRememberMe.isChecked()) {
                        user.RememberLoginSuccess(preferences);
                    }
                    Intent intent = new Intent(getApplicationContext(), ProfilePageActivity.class);
                    intent.putExtra(EXTRA_MESSAGE, message);
                    intent.putExtra(EXTRA_MESSAGE_2, user);
                    startActivity(intent);
                    finish();
                } else {
                    etUsername.setError("Wrong username or password");
                    etUsername.setText("");
                    etPassword.setText("");
                }
            }
        };

        etUsername = findViewById(R.id.et_username);
        etPassword = findViewById(R.id.et_password);
        cbRememberMe = findViewById(R.id.cb_rememberMe);
        btLogin = findViewById(R.id.bt_login);

        btLogin.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String temp_user = etUsername.getText().toString();
                String temp_pass = etPassword.getText().toString();
                if (!TextUtils.isEmpty(temp_user) && !TextUtils.isEmpty(temp_pass)) {
                    user = new User(etUsername.getText().toString(), etPassword.getText().toString());
                    thread = new Thread(new HTTPRequest(mainHandler, user));
                    thread.start();
                } else {
                    etUsername.setError("Please, fill-out the form");
                    etUsername.setText("");
                    etPassword.setText("");
                }
            }
        });
    }
}