学习Android Studio开发工具之Activity3（框架2）
16lz
2021-01-23
接上文学习Android Studio开发工具之Activity3（框架1）
本篇介绍Android Studio提供的用户登录框架，新建一个Module命名为Login，选择Login Activity，如图：
等待Android Studio编译完成安装到虚拟机后的效果如图：
可以看到使用ScrollView布局使得登录编辑框更加人性化。
先来看布局文件 activity_login.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:gravity="center_horizontal" android:orientation="vertical" android:paddingBottom="@dimen/activity_vertical_margin" android:paddingLeft="@dimen/activity_horizontal_margin" android:paddingRight="@dimen/activity_horizontal_margin" android:paddingTop="@dimen/activity_vertical_margin" tools:context="com.hitsz.xiaokai.login.LoginActivity"> <!-- Login progress --> <ProgressBar android:id="@+id/login_progress" style="?android:attr/progressBarStyleLarge" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginBottom="8dp" android:visibility="gone"/> <ScrollView android:id="@+id/login_form" android:layout_width="match_parent" android:layout_height="match_parent"> <LinearLayout android:id="@+id/email_login_form" android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="vertical"> <android.support.design.widget.TextInputLayout android:layout_width="match_parent" android:layout_height="wrap_content"> <AutoCompleteTextView android:id="@+id/email" android:layout_width="match_parent" android:layout_height="wrap_content" android:hint="@string/prompt_email" android:inputType="textEmailAddress" android:maxLines="1" android:singleLine="true"/> </android.support.design.widget.TextInputLayout> <android.support.design.widget.TextInputLayout android:layout_width="match_parent" android:layout_height="wrap_content"> <EditText android:id="@+id/password" android:layout_width="match_parent" android:layout_height="wrap_content" android:hint="@string/prompt_password" android:imeActionId="@+id/login" android:imeActionLabel="@string/action_sign_in_short" android:imeOptions="actionUnspecified" android:inputType="textPassword" android:maxLines="1" android:singleLine="true"/> </android.support.design.widget.TextInputLayout> <Button android:id="@+id/email_sign_in_button" style="?android:textAppearanceSmall" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_marginTop="16dp" android:text="@string/action_sign_in" android:textStyle="bold"/> </LinearLayout> </ScrollView></LinearLayout>这里使用了扩展的控件AutoCompleteTextView，输入文本类型为textEmailAddress，用户输入时会检查类型是否满足要求，而且会自动保存用户Email账户到本地，下次登录会提示历史记录点击填充。这里需要在AndroidManifest中配置相应的权限。
权限声明：
<!-- To auto-complete the email text field in the login form with the user's emails --> <uses-permission android:name="android.permission.GET_ACCOUNTS"/> <uses-permission android:name="android.permission.READ_PROFILE"/> <uses-permission android:name="android.permission.READ_CONTACTS"/>接下来再看重要的登录实现逻辑框架：
package com.hitsz.xiaokai.login;import android.animation.Animator;import android.animation.AnimatorListenerAdapter;import android.annotation.TargetApi;import android.content.pm.PackageManager;import android.support.annotation.NonNull;import android.support.design.widget.Snackbar;import android.support.v7.app.AppCompatActivity;import android.app.LoaderManager.LoaderCallbacks;import android.content.CursorLoader;import android.content.Loader;import android.database.Cursor;import android.net.Uri;import android.os.AsyncTask;import android.os.Build;import android.os.Bundle;import android.provider.ContactsContract;import android.text.TextUtils;import android.view.KeyEvent;import android.view.View;import android.view.View.OnClickListener;import android.view.inputmethod.EditorInfo;import android.widget.ArrayAdapter;import android.widget.AutoCompleteTextView;import android.widget.Button;import android.widget.EditText;import android.widget.TextView;import java.util.ArrayList;import java.util.List;import static android.Manifest.permission.READ_CONTACTS;/** * A login screen that offers login via email/password. * 登录界面有email和password两个输入框 */public class LoginActivity extends AppCompatActivity implements LoaderCallbacks<Cursor> { /** * Id to identity READ_CONTACTS permission request. * 读取用户通讯录 */ private static final int REQUEST_READ_CONTACTS = 0; /** * A dummy authentication store containing known user names and passwords. * TODO: remove after connecting to a real authentication system. * 模拟授权的账户 */ private static final String[] DUMMY_CREDENTIALS = new String[]{ "[email protected]:hello", "[email protected]:world" }; /** * Keep track of the login task to ensure we can cancel it if requested. * 声明用户登录引用，方便随时撤销登录请求 */ private UserLoginTask mAuthTask = null; // UI references.界面控件 private AutoCompleteTextView mEmailView; private EditText mPasswordView; private View mProgressView; private View mLoginFormView; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_login); // Set up the login form. mEmailView = (AutoCompleteTextView) findViewById(R.id.email); populateAutoComplete(); mPasswordView = (EditText) findViewById(R.id.password); mPasswordView.setOnEditorActionListener(new TextView.OnEditorActionListener() { @Override public boolean onEditorAction(TextView textView, int id, KeyEvent keyEvent) { //当用户处在输入密码编辑框，软键盘打开，输入确定按钮(EditorInfo.IME_NUL)时尝试登录 if (id == R.id.login || id == EditorInfo.IME_NULL) { attemptLogin(); return true; } return false; } }); Button mEmailSignInButton = (Button) findViewById(R.id.email_sign_in_button); //登录按钮点击事件 mEmailSignInButton.setOnClickListener(new OnClickListener() { @Override public void onClick(View view) { attemptLogin(); } }); //登录界面和进度条界面 mLoginFormView = findViewById(R.id.login_form); mProgressView = findViewById(R.id.login_progress); } //加载本地账户 private void populateAutoComplete() { if (!mayRequestContacts()) { return; } getLoaderManager().initLoader(0, null, this); } private boolean mayRequestContacts() { if (Build.VERSION.SDK_INT < Build.VERSION_CODES.M) { return true; } if (checkSelfPermission(READ_CONTACTS) == PackageManager.PERMISSION_GRANTED) { return true; } if (shouldShowRequestPermissionRationale(READ_CONTACTS)) { Snackbar.make(mEmailView, R.string.permission_rationale, Snackbar.LENGTH_INDEFINITE) .setAction(android.R.string.ok, new View.OnClickListener() { @Override @TargetApi(Build.VERSION_CODES.M) public void onClick(View v) { requestPermissions(new String[]{READ_CONTACTS}, REQUEST_READ_CONTACTS); } }); } else { requestPermissions(new String[]{READ_CONTACTS}, REQUEST_READ_CONTACTS); } return false; } /** * Callback received when a permissions request has been completed. */ @Override public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) { if (requestCode == REQUEST_READ_CONTACTS) { if (grantResults.length == 1 && grantResults[0] == PackageManager.PERMISSION_GRANTED) { populateAutoComplete(); } } } /** * Attempts to sign in or register the account specified by the login form.在登录界面尝试注册登录账户，如果登录信息不满足要求显示出错信息 * If there are form errors (invalid email, missing fields, etc.), the * errors are presented and no actual login attempt is made. */ private void attemptLogin() { if (mAuthTask != null) { return; } // Reset errors. mEmailView.setError(null); mPasswordView.setError(null); // Store values at the time of the login attempt. String email = mEmailView.getText().toString(); String password = mPasswordView.getText().toString(); boolean cancel = false; View focusView = null; // Check for a valid password, if the user entered one. //检查密码有效性 if (!TextUtils.isEmpty(password) && !isPasswordValid(password)) { mPasswordView.setError(getString(R.string.error_invalid_password)); focusView = mPasswordView; cancel = true; } // Check for a valid email address. if (TextUtils.isEmpty(email)) { mEmailView.setError(getString(R.string.error_field_required)); focusView = mEmailView; cancel = true; } else if (!isEmailValid(email)) { mEmailView.setError(getString(R.string.error_invalid_email)); focusView = mEmailView; cancel = true; } //取消登录 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. showProgress(true); mAuthTask = new UserLoginTask(email, password); mAuthTask.execute((Void) null); } } //判断邮箱有效性，必须含有"@" private boolean isEmailValid(String email) { //TODO: Replace this with your own logic return email.contains("@"); } //密码有效性判断，必须长度大于4 private boolean isPasswordValid(String password) { //TODO: Replace this with your own logic return password.length() > 4; } /** * Shows the progress UI and hides the login form. * 显示进度条界面，关闭登录窗体 */ @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); mLoginFormView.setVisibility(show ? View.GONE : 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); } }); mProgressView.setVisibility(show ? View.VISIBLE : View.GONE); mProgressView.animate().setDuration(shortAnimTime).alpha( show ? 1 : 0).setListener(new AnimatorListenerAdapter() { @Override public void onAnimationEnd(Animator animation) { mProgressView.setVisibility(show ? View.VISIBLE : View.GONE); } }); } else { // The ViewPropertyAnimator APIs are not available, so simply show // and hide the relevant UI components. mProgressView.setVisibility(show ? View.VISIBLE : View.GONE); mLoginFormView.setVisibility(show ? View.GONE : View.VISIBLE); } } @Override public Loader<Cursor> onCreateLoader(int i, Bundle bundle) { return new CursorLoader(this, // Retrieve data rows for the device user's 'profile' contact.遍历用户的profile数据 Uri.withAppendedPath(ContactsContract.Profile.CONTENT_URI, ContactsContract.Contacts.Data.CONTENT_DIRECTORY), ProfileQuery.PROJECTION, // Select only email addresses.选择邮箱地址 ContactsContract.Contacts.Data.MIMETYPE + " = ?", new String[]{ContactsContract.CommonDataKinds.Email .CONTENT_ITEM_TYPE}, // Show primary email addresses first. Note that there won't be // a primary email address if the user hasn't specified one.按照用户的输入显示排序的邮箱地址 ContactsContract.Contacts.Data.IS_PRIMARY + " DESC"); } @Override public void onLoadFinished(Loader<Cursor> cursorLoader, Cursor cursor) { List<String> emails = new ArrayList<>(); cursor.moveToFirst(); while (!cursor.isAfterLast()) { emails.add(cursor.getString(ProfileQuery.ADDRESS)); cursor.moveToNext(); } addEmailsToAutoComplete(emails); } @Override public void onLoaderReset(Loader<Cursor> cursorLoader) { } private void addEmailsToAutoComplete(List<String> emailAddressCollection) { //Create adapter to tell the AutoCompleteTextView what to show in its dropdown list.创建自动填充的提示列表适配器 ArrayAdapter<String> adapter = new ArrayAdapter<>(LoginActivity.this, android.R.layout.simple_dropdown_item_1line, emailAddressCollection); mEmailView.setAdapter(adapter); } private interface ProfileQuery { String[] PROJECTION = { ContactsContract.CommonDataKinds.Email.ADDRESS, ContactsContract.CommonDataKinds.Email.IS_PRIMARY, }; int ADDRESS = 0; int IS_PRIMARY = 1; } /** * Represents an asynchronous login/registration task used to authenticate * the user. * 显示异步登录注册任务，继承异步任务 */ public class UserLoginTask extends AsyncTask<Void, Void, Boolean> { private final String mEmail; private final String mPassword; UserLoginTask(String email, String password) { mEmail = email; mPassword = password; } @Override protected Boolean doInBackground(Void... params) { // TODO: attempt authentication against a network service.通过网络服务尝试获取授权 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.如果账户存在且密码匹配成功返回true return pieces[1].equals(mPassword); } } // TODO: register the new account here.注册 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(); } } //取消任务 @Override protected void onCancelled() { mAuthTask = null; showProgress(false); } }}