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学习Android Studio开发工具之Activity3(框架2)

2017-03-16

学习Android Studio开发工具之Activity3(框架2),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。

学习Android Studio开发工具之Activity3(框架2),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:

这里写图片描述

等待Android Studio编译完成安装到虚拟机后的效果如图:

这里写图片描述

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

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。

这里写图片描述
这里写图片描述

权限声明:

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 {

/**

* 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[]{

"foo@example.com:hello", "bar@example.com: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&#39;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 onCreateLoader(int i, Bundle bundle) {

return new CursorLoader(this,

// Retrieve data rows for the device user&#39;s &#39;profile&#39; 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&#39;t be

// a primary email address if the user hasn&#39;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 cursorLoader, Cursor cursor) {

List emails = new ArrayList<>();

cursor.moveToFirst();

while (!cursor.isAfterLast()) {

emails.add(cursor.getString(ProfileQuery.ADDRESS));

cursor.moveToNext();

}

addEmailsToAutoComplete(emails);

}

@Override

public void onLoaderReset(Loader cursorLoader) {

}

private void addEmailsToAutoComplete(List 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 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 {

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);

}

}

}

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