Android SharedPreference 值在应用程序关闭时被清除

如何解决Android SharedPreference 值在应用程序关闭时被清除

我将我的 UserId 保存在 SharedPreference 上以备将来使用。但是，如果我关闭该应用程序或终止该应用程序，这些数据就会被清除。

用于保存的代码：

 SharedPreferences app_preferences = PreferenceManager.getDefaultSharedPreferences(getApplicationContext());
    SharedPreferences.Editor editor = app_preferences.edit();
    editor.clear();
    editor.putString("USERID",valu1);
    editor.apply();

要检索的代码：

 SharedPreferences app_preferences = PreferenceManager.getDefaultSharedPreferences(getApplicationContext());
        userID = app_preferences.getString("USERID","");
     

有什么建议吗？

解决方法

apply() 方法是异步的并且在后台线程上工作。它将数据缓存在 RAM 中并等待，直到它有足够的资源将数据写入永久存储。考虑到这一点，如果您立即关闭您的应用程序，您可能会丢失数据。与 apply() 不同，commit 在 UI 线程上同步运行，它是否有保证的写入但会暂停 UI 线程片刻。等待是微不足道的。考虑使用 commit() 而不是 apply() 看看它是否有帮助。

,

为此创建一个会话管理器，这是一个单独的类。

public class SessionManager {
   
    SharedPreferences pref;

    Editor editor;

    Context _context;

    int PRIVATE_MODE = 0;

    private static final String PREF_NAME = "Android_Session";

    private static final String IS_LOGIN = "IsLoggedIn";

    // User name,Email,Id (make variable public to access from outside)
    public static final String KEY_PHONE = "phone";

    public static final String KEY_EMAIL = "email";

    public static final String KEY_ID = "id";

    // Constructor
    public SessionManager(Context context) {
        this._context = context;
        pref = _context.getSharedPreferences(PREF_NAME,PRIVATE_MODE);
        editor = pref.edit();
    }

    /**
     * Create login session when user login first time call this.
     */
    public void createLoginSession(String phone,String email,String id) {
        
        editor.putBoolean(IS_LOGIN,true);
        editor.putString(KEY_PHONE,phone);
        editor.putString(KEY_EMAIL,email);
        editor.putString(KEY_ID,id);
        editor.commit();
    }

    
    /**
     * Check user is login or not if not.
     * This will used in dynamic app where session expired from server sideit will redirect to login page.  
     */
    public void checkLogin() {
       
        if (!this.isLoggedIn()) {

            // user is not logged in then redirect to Login Activity
            Intent i = new Intent(_context,Login.class);
            
            // Add flags launch modes
            i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
            i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
            _context.startActivity(i);
        }
    }

    /**
     * Get stored session data
     */
    public HashMap<String,String> getUserDetails() {
        HashMap<String,String> user = new HashMap<String,String>();
        

        user.put(KEY_PHONE,pref.getString(KEY_PHONE,null));
        user.put(KEY_EMAIL,pref.getString(KEY_EMAIL,null));
        user.put(KEY_ID,pref.getString(KEY_ID,null));

        return user;
    }

    /**
     * Clear session details
     */
    public void logoutUser() {

        editor.clear();
        editor.commit();

        // After logout redirect user to Login Activity
        Intent i = new Intent(_context,Login.class);
        // Add Flags (Launch Modes)
        i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
        i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK);


        _context.startActivity(i);
    }

    /**
     * Check if user login or not
     **/
    public boolean isLoggedIn() {
        return pref.getBoolean(IS_LOGIN,false);
    }
}

现在检索像

这样的值

   SessionManager session = new SessionManager(getApplicationContext());
   HashMap<String,String> user = session.getUserDetails();
   String id = user.get(SessionManager.KEY_ID); 

识别登录

SessionManager session = new SessionManager(getApplicationContext());
 if (!session.isLoggedIn()) {                             
//ToDo
} else {
}