ADT21抢鲜使用
伴着Android4.2的发布，楼主我也更新到了API17，adt换成21，抢鲜播报一下新变化。
首先是新建工程，系统提供了几个新模板
这个LoginActivity让人眼前一亮，并且Activity的代码都已经写好了，开发起来so easy！
这个MasterDetailFlow据IOS的同事说在苹果SDK早就有了，看来谷歌是迎面赶上啊。
再来看一张布局器
多个屏幕尺寸的预览图同时展示，更好的进行屏幕适配工作
下面是LoginActivity的代码
package com.example.adt21test;import android.animation.Animator;import android.animation.AnimatorListenerAdapter;import android.annotation.TargetApi;import android.app.Activity;import android.os.AsyncTask;import android.os.Build;import android.os.Bundle;import android.text.TextUtils;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;/** * Activity which displays a login screen to the user, offering registration as * well. */public class LoginActivity extends Activity {/** * A dummy authentication store containing known user names and passwords. * TODO: remove after connecting to a real authentication system. */private static final String[] DUMMY_CREDENTIALS = new String[] {"foo@example.com:hello", "bar@example.com:world" };/** * 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 email and password at the time of the login attempt.private String mEmail;private String mPassword;// UI references.private EditText mEmailView;private EditText mPasswordView;private View mLoginFormView;private View mLoginStatusView;private TextView mLoginStatusMessageView;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_login);// Set up the login form.mEmail = getIntent().getStringExtra(EXTRA_EMAIL);mEmailView = (EditText) findViewById(R.id.email);mEmailView.setText(mEmail);mPasswordView = (EditText) findViewById(R.id.password);mPasswordView.setOnEditorActionListener(new TextView.OnEditorActionListener() {@Overridepublic 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);findViewById(R.id.sign_in_button).setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View view) {attemptLogin();}});}@Overridepublic boolean onCreateOptionsMenu(Menu menu) {super.onCreateOptionsMenu(menu);getMenuInflater().inflate(R.menu.activity_login, 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() {if (mAuthTask != null) {return;}// Reset errors.mEmailView.setError(null);mPasswordView.setError(null);// Store values at the time of the login attempt.mEmail = 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(mEmail)) {mEmailView.setError(getString(R.string.error_field_required));focusView = mEmailView;cancel = true;} else if (!mEmail.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((Void) null);}}/** * 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() {@Overridepublic 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() {@Overridepublic 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> {@Overrideprotected Boolean doInBackground(Void... params) {// TODO: attempt authentication against a network service.try {// Simulate network access.Thread.sleep(2000);} catch (InterruptedException e) {return false;}for (String credential : DUMMY_CREDENTIALS) {String[] pieces = credential.split(":");if (pieces[0].equals(mEmail)) {// Account exists, return true if the password matches.return pieces[1].equals(mPassword);}}// TODO: register the new account here.return true;}@Overrideprotected void onPostExecute(final Boolean success) {mAuthTask = null;showProgress(false);if (success) {finish();} else {mPasswordView.setError(getString(R.string.error_incorrect_password));mPasswordView.requestFocus();}}@Overrideprotected void onCancelled() {mAuthTask = null;showProgress(false);}}}