本文主要講述了利用sharedpreference實現記住密碼與自動登陸功能

根據checkbox的狀態存儲用戶名與密碼

將結果保存在自定義的application中，成為全局變量

布局文件

<?xml version="1.0" encoding="utf-8"?> <ScrollView xmlns:android="http://schemas.android.com/apk/res/android"android:layout_width="fill_parent"android:layout_height="fill_parent"android:fitsSystemWindows="true"><LinearLayout android:orientation="vertical"android:layout_width="match_parent"android:layout_height="wrap_content"android:paddingTop="56dp"android:paddingLeft="24dp"android:paddingRight="24dp"><ImageView android:src="@drawable/logo"android:layout_width="wrap_content"android:layout_height="72dp"android:layout_marginBottom="24dp"android:layout_gravity="center_horizontal" /><!-- Email Label --><android.support.design.widget.TextInputLayout android:layout_width="match_parent"android:layout_height="wrap_content"android:layout_marginTop="8dp"android:layout_marginBottom="8dp"><EditText android:id="@+id/input_email"android:layout_width="match_parent"android:layout_height="wrap_content"android:inputType="textEmailAddress"android:hint="Phone" /></android.support.design.widget.TextInputLayout><!-- Password Label --><android.support.design.widget.TextInputLayout android:layout_width="match_parent"android:layout_height="wrap_content"android:layout_marginTop="8dp"android:layout_marginBottom="8dp"><EditText android:id="@+id/input_password"android:layout_width="match_parent"android:layout_height="wrap_content"android:inputType="textPassword"android:hint="Password"/></android.support.design.widget.TextInputLayout><LinearLayout android:layout_width="match_parent"android:layout_height="wrap_content"android:orientation="horizontal"android:gravity="center_horizontal"><CheckBox android:id="@+id/rm_pass"android:layout_width="wrap_content"android:layout_height="wrap_content"android:text="記住密碼"android:layout_marginRight="30dp"android:checked="true"/><CheckBox android:id="@+id/au_login"android:layout_width="wrap_content"android:layout_height="wrap_content"android:text="自動登陸"android:layout_marginLeft="30dp"/></LinearLayout><android.support.v7.widget.AppCompatButton android:id="@+id/btn_login"android:layout_width="fill_parent"android:layout_height="wrap_content"android:layout_marginTop="24dp"android:layout_marginBottom="24dp"android:padding="12dp"android:text="Login"/><TextView android:id="@+id/link_signup"android:layout_width="fill_parent"android:layout_height="wrap_content"android:layout_marginBottom="24dp"android:text="No account yet? Create one"android:gravity="center"android:textSize="16dip"/></LinearLayout> </ScrollView>

登陸界面

package com.zj.login;import android.app.Activity; import android.app.ProgressDialog; import android.content.Intent; import android.content.SharedPreferences; import android.os.Bundle; import android.support.v7.app.AppCompatActivity; import android.util.Log; import android.util.Patterns; import android.view.View; import android.widget.Button; import android.widget.CheckBox; import android.widget.EditText; import android.widget.TextView; import android.widget.Toast;import com.zj.cafetriafood.R;import butterknife.Bind; import butterknife.ButterKnife;/*** A login screen that offers login via email/password.*/ public class LoginActivity extends AppCompatActivity {private static final String TAG = "LoginActivity";private static final int REQUEST_SIGNUP = 0;private SharedPreferences sp;@Bind(R.id.input_email) EditText _emailText;@Bind(R.id.input_password) EditText _passwordText;@Bind(R.id.btn_login) Button _loginButton;@Bind(R.id.link_signup) TextView _signupLink;@Bind(R.id.rm_pass) CheckBox _rmpass;@Bind(R.id.au_login) CheckBox _aulogin;@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_login);ButterKnife.bind(this);sp = this.getSharedPreferences("userInfo", Activity.MODE_PRIVATE);_loginButton.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View v) {login();}});_signupLink.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View v) {// Start the Signup activityIntent intent = new Intent(getApplicationContext(), SignupActivity.class);startActivityForResult(intent, REQUEST_SIGNUP);}});if(sp.getBoolean("ISCHECK", false)){_rmpass.setChecked(true);_emailText.setText(sp.getString("USER_NAME", ""));_passwordText.setText(sp.getString("PASSWORD", ""));if(sp.getBoolean("AUTO_ISCHECK", false)){//設置默認是自動登錄狀態_aulogin.setChecked(true);//跳轉界面//Intent intent = new Intent(LoginActivity.this,MainActivity.class);//startActivity(intent);this.finish();}}}public void login() {Log.d(TAG, "Login");if (!validate()) {onLoginFailed();return;}_loginButton.setEnabled(false);final ProgressDialog progressDialog = new ProgressDialog(LoginActivity.this,R.style.AppTheme_Dark_Dialog);progressDialog.setIndeterminate(true);progressDialog.setMessage("Authenticating...");progressDialog.show();String email = _emailText.getText().toString();String password = _passwordText.getText().toString();// TODO: Implement your own authentication logic here.Log.i("test","email+password="+email+","+password);if(!email.equals("123")||!password.equals("123456")){progressDialog.dismiss();_loginButton.setEnabled(true);_emailText.setText("");_passwordText.setText("");Toast.makeText(getApplication(), "用戶名或密碼錯誤", Toast.LENGTH_SHORT).show();return;}if(_rmpass.isChecked()){//記住用戶名、密碼、SharedPreferences.Editor editor = sp.edit();editor.putString("USER_NAME", email);editor.putString("PASSWORD", password);editor.commit();sp.edit().putBoolean("ISCHECK", true).commit();}else{sp.edit().putBoolean("ISCHECK", true).commit();}if (_aulogin.isChecked()){sp.edit().putBoolean("AUTO_ISCHECK", true).commit();}else{sp.edit().putBoolean("AUTO_ISCHECK", false).commit();}new android.os.Handler().postDelayed(new Runnable() {public void run() {// On complete call either onLoginSuccess or onLoginFailedonLoginSuccess();// onLoginFailed();progressDialog.dismiss();}}, 3000);}@Overrideprotected void onActivityResult(int requestCode, int resultCode, Intent data) {if (requestCode == REQUEST_SIGNUP) {if (resultCode == RESULT_OK) {// TODO: Implement successful signup logic here// By default we just finish the Activity and log them in automaticallythis.finish();}}}@Overridepublic void onBackPressed() {// Disable going back to the MainActivitymoveTaskToBack(true);}public void onLoginSuccess() {_loginButton.setEnabled(true);finish();}public void onLoginFailed() {Toast.makeText(getBaseContext(), "Login failed", Toast.LENGTH_LONG).show();_loginButton.setEnabled(true);}public boolean validate() {boolean valid = true;String email = _emailText.getText().toString();String password = _passwordText.getText().toString();if (email.isEmpty() || !Patterns.PHONE.matcher(email).matches()) {_emailText.setError("enter a valid phone number");valid = false;} else {_emailText.setError(null);}if (password.isEmpty() || password.length() < 4 || password.length() > 10) {_passwordText.setError("between 4 and 10 alphanumeric characters");valid = false;} else {_passwordText.setError(null);}return valid;} }

MainActivity

package com.zj.cafetriafood;import android.app.Activity; import android.content.Intent; import android.content.SharedPreferences; import android.os.Bundle; import android.support.v7.app.AppCompatActivity; import android.widget.TextView;import com.zj.application.MyApplication; import com.zj.login.LoginActivity;import butterknife.Bind; import butterknife.ButterKnife;public class MainActivity extends AppCompatActivity {private SharedPreferences sp;private MyApplication myApplication;@Bind(R.id.text_user) TextView text_user;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);ButterKnife.bind(this);sp = this.getSharedPreferences("userInfo", Activity.MODE_PRIVATE);if(sp.getBoolean("AUTO_ISCHECK", false)){myApplication= (MyApplication) getApplication();myApplication.setUsername(sp.getString("USER_NAME",""));}else{Intent intent = new Intent(this, LoginActivity.class);startActivity(intent);}text_user.setText(myApplication.getUsername());}}

MyApplication

package com.zj.application;import android.app.Application;/*** Created by jjx on 2016/5/22.*/ public class MyApplication extends Application{public String getUsername() {return username;}public void setUsername(String username) {this.username = username;}String username;@Overridepublic void onCreate() {super.onCreate();setUsername("用戶名");} }

參考鏈接

Android 記住密碼和自動登錄界面的實現（SharedPreferences 的用法） - liuyiming_的專欄 - 博客頻道 - CSDN.NET

Android中Application類用法 - Harvey Ren - 博客園

Application對象的生命周期是整個程序中最長的，它的生命周期就等于這個程序的生命周期。因為它是全局的單例的，所以在不同的Activity,Service中獲得的對象都是同一個對象。所以可以通過Application來進行一些，如：數據傳遞、數據共享和數據緩存等操作。

在Android中，可以通過繼承Application類來實現應用程序級的全局變量，這種全局變量方法相對靜態類更有保障，直到應用的所有Activity全部被destory掉之后才會被釋放掉。

效果如下

總結

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