Question

我正在创建一个项目，我有一个登录屏幕，用于登录用户应用。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

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 2

将用户的登录信息保存在SharedPeference中：

617,5 - 52 = 565,5
565,5 - 35 = 530,5 and so on

当用户注销时，将布尔“LoggedIn”保存为false：

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

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

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

Answer 3

如果用户登录应用时共享首选项，则希望使用共享首选项执行此操作。

mv source/files destination/

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", true).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);
prefs.edit().putBoolean("staylogin", false).commit();

Answer 4

试试这个，工作代码

在您的登录页面

    // 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<String, String> getUserDetails(){
        HashMap<String, String> user = new HashMap<String, String>();
        // 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);
    }
}

此外，您希望参考查找以下链接

Link For Reference

一次登录

4 个答案: