登录一次

我正在创建一个项目，我有一个登录屏幕，用于登录应用程序。 此登录屏幕应该只在第一次可见，因此用户可以填写并登录，但是当用户第二次打开应用程序时，应用程序必须显示main.activity。 如何使用共享首选项执行此操作？

Answer 1

在SharedPeference中保存用户的登录信息：

SharedPreferences preferences = getSharedPreferences("preference",MODE_PRIVATE); preferences.edit().putBoolean("LoggedIn", true).apply(); 

当用户注销时，将布尔“LoggedIn”保存为false：

 preferences.edit().putBoolean("LoggedIn", false).apply(); 

在SplashActivity中，从sharedprefence获取值并调用相应的活动：

 boolean loggedIn = preferences.getBoolean("LoggedIn", false); if(loggedIn){ // call main activity }else{ //call login activity } 

Answer 2

首先，检查用户之前是否已登录。 使用SharedPreferences：

 SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(getActivity()); Boolean loggedIn = prefs.getBoolean("loggedIn", false); if(loggedIn != null && loggedIn) { //open main activity }else{ //open login page } 

当用户登录时，将登录信息保存到SharedPreferences：

 SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(getActivity()); prefs.edit().putBoolean("loggedIn", true); 

这就是你所需要的一切。

Answer 3

试试这个，工作代码

在您的登录页面中

  // Session Manager Class SessionManagerFor_Signin session; private EditText EMAIL, PASSWORD; private Button login; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); requestWindowFeature(Window.FEATURE_NO_TITLE); setContentView(R.layout.sign_in); // Session Manager session = new SessionManagerFor_Signin(getApplicationContext()); login = (Button) findViewById(R.id.loginbutton); EMAIL = (EditText) findViewById(R.id.EmaileditText1); PASSWORD = (EditText) findViewById(R.id.passwordeditText2); login.setOnClickListener(this); } @Override public void onClick(View v) { switch (v.getId()) { case R.id.loginbutton: email = EMAIL.getText().toString(); password = PASSWORD.getText().toString(); if (email.equals("") || password.equals("")) { // user didn't entered user name or password // Show alert asking him to enter the details alert.showAlertDialog(sign_in.this, "Login Failed...","Please Enter Email and Password", false); } else { // fetch the Password form database for respective Email storedPassword = DB.getSinlgeEntry(email); if (password.equals(storedPassword)) { session.createLoginSession(email, password); Toast.makeText(sign_in.this, "Login Successfull",Toast.LENGTH_LONG).show(); Intent intent = new Intent(sign_in.this, Page1_Landing.class); startActivity(intent); finish(); } } break; } 

SessionManagerFor_Signin.java

 public class SessionManagerFor_Signin { // Shared Preferences SharedPreferences pref; // Editor for Shared preferences Editor editor; // Context Context _context; // Shared pref mode int PRIVATE_MODE = 0; // Sharedpref file name private static final String PREF_NAME = "SharedPref"; // All Shared Preferences Keys private static final String IS_LOGIN = "IsLoggedIn"; // User name (make variable public to access from outside) public static final String KEY_EMAILID = "email"; // Email address (make variable public to access from outside) public static final String KEY_PASSWORD = "password"; // Constructor public SessionManagerFor_Signin(Context context) { this._context = context; pref = _context.getSharedPreferences(PREF_NAME, PRIVATE_MODE); editor = pref.edit(); } // Create login session public void createLoginSession(String email, String password) { // Storing login value as TRUE editor.putBoolean(IS_LOGIN, true); // Storing name in pref editor.putString(KEY_EMAILID, email); // Storing email in pref editor.putString(KEY_PASSWORD, password); // commit changes editor.commit(); } /** * Check login method wil check user login status * If false it will redirect user to login page * Else won't do anything * */ public void checkLogin() { // Check login status if(this.isLoggedIn()) { Intent intent = new Intent(_context,Page1_Landing.class); // Closing all the Activities intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP); // Add new Flag to start new Activity intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK); //Toast.makeText(getApplicationContext(),email, Toast.LENGTH_LONG).show(); _context.startActivity(intent); } else { // user is not logged in redirect him to Login Activity Intent i = new Intent(_context, MainActivity.class); // Closing all the Activities i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP); // Add new Flag to start new Activity i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK); // Staring Login Activity _context.startActivity(i); } } /** * Get stored session data * */ public HashMap getUserDetails(){ HashMap user = new HashMap(); // user mail user.put(KEY_EMAILID, pref.getString(KEY_EMAILID, null)); // user password user.put(KEY_PASSWORD, pref.getString(KEY_PASSWORD, null)); // return user return user; } /** * Clear session details * */ public void logoutUser() { // Clearing all data from Shared Preferences editor.clear(); editor.commit(); Intent intent = new Intent(_context, MainActivity.class); intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK); _context.startActivity(intent); } /** * Quick check for login * **/ // Get Login State public boolean isLoggedIn() { return pref.getBoolean(IS_LOGIN, false); } } 

您还需要参考查找以下链接

链接供参考

Answer 4

如果您希望在用户登录应用程序时使用共享首选项共享首选项，请执行此操作。

 SharedPreferences prefs = getSharedPreferences("MyApp", MODE_PRIVATE); prefs.edit().putBoolean("staylogin", true).commit(); 

如果你想注销但是点击设置首选项..

 SharedPreferences prefs = getSharedPreferences("MyApp", MODE_PRIVATE); prefs.edit().putBoolean("staylogin", false).commit(); 

为了在没有登录屏幕的情况下启动您的应用程序，您可以在其他人之前使用启动画面并检查共享首选项…

 SharedPreferences prefs = getSharedPreferences("MyApp", MODE_PRIVATE); Boolean state = prefs.getString("staylogin", false); if (state) { //Start Main Activity } else { //Start Log in activity }