LoginActivity.java

package com.example.myaccountmechanism;

import android.accounts.Account;
import android.accounts.AccountAuthenticatorActivity;
import android.accounts.AccountManager;
import android.animation.Animator;
import android.animation.AnimatorListenerAdapter;
import android.annotation.TargetApi;
import android.os.AsyncTask;
import android.os.Build;
import android.os.Bundle;
import android.text.TextUtils;
import android.util.Log;
import android.view.KeyEvent;
import android.view.Menu;
import android.view.View;
import android.view.inputmethod.EditorInfo;
import android.widget.EditText;
import android.widget.TextView;

/**
 * Make sure we have a username and password, and pass it over the net to our account validation service;
 * if it is OK, then register it ("create an account") locally so the user can remain signed in.
 */
public class LoginActivity extends AccountAuthenticatorActivity {
	
	private static final String TAG = MainActivity.TAG;

	/**
	 * The default email to populate the email field with.
	 */
	public static final String EXTRA_EMAIL = "com.example.android.authenticatordemo.extra.EMAIL";

	/**
	 * Keep track of the login task to ensure we can cancel it if requested.
	 */
	private UserLoginTask mAuthTask = null;

	// Values for username and password at the time of the login attempt.
	private String mUserName;
	private String mPassword;

	// UI references.
	private EditText mEmailView;
	private EditText mPasswordView;
	private View mLoginFormView;
	private View mLoginStatusView;
	private TextView mLoginStatusMessageView;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		Log.d(TAG, "LoginActivity.onCreate");
		super.onCreate(savedInstanceState);

		setContentView(R.layout.activity_login);

		// Set up the login form.
		mUserName = getIntent().getStringExtra(EXTRA_EMAIL);
		mEmailView = (EditText) findViewById(R.id.email);
		mEmailView.setText(mUserName);

		mPasswordView = (EditText) findViewById(R.id.password);
		mPasswordView.setOnEditorActionListener(new TextView.OnEditorActionListener() {
					@Override
					public boolean onEditorAction(TextView textView, int id,
							KeyEvent keyEvent) {
						if (id == R.id.login || id == EditorInfo.IME_NULL) {
							attemptLogin();
							return true;
						}
						return false;
					}
				});

		mLoginFormView = findViewById(R.id.login_form);
		mLoginStatusView = findViewById(R.id.login_status);
		mLoginStatusMessageView = (TextView) findViewById(R.id.login_status_message);

	}
	
	public void register(View v) {
		attemptLogin();
	}

	@Override
	public boolean onCreateOptionsMenu(Menu menu) {
		super.onCreateOptionsMenu(menu);
		getMenuInflater().inflate(R.menu.settings, menu);
		return true;
	}

	/**
	 * Attempts to sign in or register the account specified by the login form.
	 * If there are form errors (invalid email, missing fields, etc.), the
	 * errors are presented and no actual login attempt is made.
	 */
	public void attemptLogin() {
		Log.d(TAG, "LoginActivity.attemptLogin()");
		if (mAuthTask != null) {
			return;
		}

		// Reset errors.
		mEmailView.setError(null);
		mPasswordView.setError(null);

		// Store values at the time of the login attempt.
		mUserName = mEmailView.getText().toString();
		mPassword = mPasswordView.getText().toString();

		boolean cancel = false;
		View focusView = null;

		// Check for a valid password.
		if (TextUtils.isEmpty(mPassword)) {
			mPasswordView.setError(getString(R.string.error_field_required));
			focusView = mPasswordView;
			cancel = true;
		} else if (mPassword.length() < 4) {
			mPasswordView.setError(getString(R.string.error_invalid_password));
			focusView = mPasswordView;
			cancel = true;
		}

		// Check for a valid email address.
		if (TextUtils.isEmpty(mUserName)) {
			mEmailView.setError(getString(R.string.error_field_required));
			focusView = mEmailView;
			cancel = true;
		} else if (!mUserName.contains("@")) {
			mEmailView.setError(getString(R.string.error_invalid_email));
			focusView = mEmailView;
			cancel = true;
		}

		if (cancel) {
			// There was an error; don't attempt login and focus the first
			// form field with an error.
			focusView.requestFocus();
		} else {
			// Show a progress spinner, and kick off a background task to
			// perform the user login attempt.
			mLoginStatusMessageView.setText(R.string.login_progress_signing_in);
			showProgress(true);
			mAuthTask = new UserLoginTask();
			mAuthTask.execute();
		}
	}

	/**
	 * Shows the progress UI and hides the login form.
	 */
	@TargetApi(Build.VERSION_CODES.HONEYCOMB_MR2)
	private void showProgress(final boolean show) {
		// On Honeycomb MR2 we have the ViewPropertyAnimator APIs, which allow
		// for very easy animations. If available, use these APIs to fade-in
		// the progress spinner.
		if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB_MR2) {
			int shortAnimTime = getResources().getInteger(
					android.R.integer.config_shortAnimTime);

			mLoginStatusView.setVisibility(View.VISIBLE);
			mLoginStatusView.animate().setDuration(shortAnimTime)
					.alpha(show ? 1 : 0)
					.setListener(new AnimatorListenerAdapter() {
						@Override
						public void onAnimationEnd(Animator animation) {
							mLoginStatusView.setVisibility(show ? View.VISIBLE
									: View.GONE);
						}
					});

			mLoginFormView.setVisibility(View.VISIBLE);
			mLoginFormView.animate().setDuration(shortAnimTime)
					.alpha(show ? 0 : 1)
					.setListener(new AnimatorListenerAdapter() {
						@Override
						public void onAnimationEnd(Animator animation) {
							mLoginFormView.setVisibility(show ? View.GONE
									: View.VISIBLE);
						}
					});
		} else {
			// The ViewPropertyAnimator APIs are not available, so simply show
			// and hide the relevant UI components.
			mLoginStatusView.setVisibility(show ? View.VISIBLE : View.GONE);
			mLoginFormView.setVisibility(show ? View.GONE : View.VISIBLE);
		}
	}

	/**
	 * Represents an asynchronous login/registration task used to authenticate
	 * the user.
	 */
	public class UserLoginTask extends AsyncTask<Void, Void, Boolean> {
		@Override
		protected Boolean doInBackground(Void... params) {
			Log.d(TAG, "LoginActivity.UserLoginTask.doInBackground()");
			
			// First time for this user on this device, try to authentication against our network service.

			// XXX write code to send a JSON request to the remote web service.
			try {
				// Simulate network access.
				Thread.sleep(1500);
			} catch (InterruptedException e) {
				return false;
			}

			// Register the new account with the on-device list of accounts.
			final Account account = new Account(mUserName, Constants.MY_ACCOUNT_TYPE);
			AccountManager am = AccountManager.get(LoginActivity.this);
			
			// XXX EPIC FAIL - don't store raw password; it MUST be encrypted.
			am.addAccountExplicitly(account, mPassword, null);
			return true;
		}

		@Override
		protected void onPostExecute(final Boolean success) {
			mAuthTask = null;
			showProgress(false);

			if (success) {
				finish();
			} else {
				mPasswordView.setError(getString(R.string.error_incorrect_password));
				mPasswordView.requestFocus();
			}
		}

		@Override
		protected void onCancelled() {
			mAuthTask = null;
			showProgress(false);
		}
	}
}