Android共享偏好重新啓動應用程序

Question

所以我正在跟隨教程，一切都很好，直到我跑了應用程序，並遇到此問題。每次我重新啓動我的應用程序，我的活動將返回到LoginActivity而不是MainActivity。這裏是我的代碼

會話管理器

SharedPreferences pref; 
SharedPreferences.Editor editor; 
Context _context; 

int PRIVATE_MODE = 0; 

private static final String PREF_NAME = "users"; 

private static final String IS_LOGIN = "IsLoggedIn"; 
//userID and userName 
public static final String KEY_USERNAME = "name"; 
// public static final String KEY_USERID = "userid"; 

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

public void createLoginSession(String username) { 
    editor.putBoolean(IS_LOGIN, true); 
    editor.putString(KEY_USERNAME, username); 
    editor.commit(); 
    // editor.putString(KEY_USERID, userID); 
} 

public void checkLogin() { 
    if (!this.isLoggedIn()) { 
     Intent i = new Intent(_context, SplashScreen.class); 
     i.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP | Intent.FLAG_ACTIVITY_NEW_TASK); 
     this._context.startActivity(i); 
    } 
} 


public HashMap<String, String> getUserDetails() { 
    HashMap<String, String> user = new HashMap<>(); 
    user.put(KEY_USERNAME, pref.getString(KEY_USERNAME, null)); 
    return user; 
} 

public void logoutUser() { 
    editor.clear(); 
    editor.commit(); 
    Intent i = new Intent(_context, SplashScreen.class); 
    i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP); 
    i.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK); 
    _context.startActivity(i); 
} 

public boolean isLoggedIn() { 
    return pref.getBoolean(IS_LOGIN, false); 
} 

登錄活動

TextView register_link; 
Button btnLogin; 
EditText eTxtUsername, eTxtPassword; 
SessionManager session; 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_login); 

    this.getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_ALWAYS_HIDDEN); 
    // 
    register_link = (TextView) findViewById(R.id.tv_register_link); 
    btnLogin = (Button) findViewById(R.id.buttonSignIn); 
    eTxtUsername = (EditText) findViewById(R.id.eTxt_username); 
    eTxtPassword = (EditText) findViewById(R.id.eTxt_password); 
    session = new SessionManager(getApplicationContext()); 
    // 
    final AlertDialog.Builder builder = new AlertDialog.Builder(LoginActivity.this); 

    Toast.makeText(this, "Login status: " + session.isLoggedIn(), Toast.LENGTH_LONG).show(); 


    register_link.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View view) { 
      Intent i = new Intent(LoginActivity.this, RegisterActivity.class); 
      LoginActivity.this.startActivity(i); 
     } 
    }); 

    btnLogin.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View view) { 

      final String username_ = eTxtUsername.getText().toString(); 
      final String password_ = eTxtPassword.getText().toString(); 

      if (isEmptyFields(username_, password_)) { 
       builder.setMessage("Please provide all fields") 
         .setNegativeButton("Retry", null) 
         .create() 
         .show(); 
      } else { 
       Response.Listener<String> responseListener = new Response.Listener<String>() { 
        @Override 
        public void onResponse(String response) { 
         try { 
          JSONObject jsonResponse = new JSONObject(response); 
          final boolean success = jsonResponse.getBoolean("success"); 

          if (success) { 
           final String userid_ = String.valueOf(jsonResponse.getInt("userid")); 

           session.createLoginSession(username_); 
           Toast.makeText(getApplicationContext(), "Login Success", 
             Toast.LENGTH_SHORT).show(); 
           Intent i = new Intent(getApplicationContext(), MainActivity.class); 
           i.putExtra("userId", userid_); 
           startActivity(i); 
           finish(); 
          } else { 
           builder.setMessage("Login Failed") 
             .setNegativeButton("Retry", null) 
             .create() 
             .show(); 
          } 
         } catch (JSONException e) { 
          e.printStackTrace(); 
         } 
        } 
       }; 

       LoginRequest loginRequest = new LoginRequest(username_, password_, responseListener); 
       RequestQueue queue = Volley.newRequestQueue(LoginActivity.this); 
       queue.add(loginRequest); 
      } 
     } 
    }); 
} 

static boolean isEmptyFields(String n1, String pw1) { 
    final boolean result; 

    if (n1.isEmpty() || pw1.isEmpty()) 
     result = true; 
    else 
     result = false; 

    return result; 
} 

主要活動

private Drawer result = null; 
private String userid; 
SessionManager session; 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main); 

    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar); 
    setSupportActionBar(toolbar); 

    final Button btn_showlist = (Button) findViewById(R.id.btn_showlist); 
    session = new SessionManager(this); 

    Toast.makeText(this, "Login status: " + session.isLoggedIn(), Toast.LENGTH_LONG).show(); 

    session.checkLogin(); 
    HashMap<String, String> user = session.getUserDetails(); 
    // userid = user.get(SessionManager.KEY_USERID); 
    String username = user.get(SessionManager.KEY_USERNAME); 

    //create drawer 
    new DrawerBuilder().withActivity(this).build(); 
    CreateDrawer(CreateAccountDrawer(), toolbar); 

    btn_showlist.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View view) { 
      Intent i = new Intent(MainActivity.this, ListActivity.class); 
      startActivity(i); 
     } 
    }); 
} 

@Override 
protected void onResume() { 
    super.onResume(); 
    result.deselect(); 
} 

//CREATE DRAWER 
@Override 
protected void attachBaseContext(Context newBase) { 
    super.attachBaseContext(IconicsContextWrapper.wrap(newBase)); 
} 

private AccountHeader CreateAccountDrawer() { 

    AccountHeader headerResult = new AccountHeaderBuilder() 
      .withActivity(this) 
      .withSelectionListEnabledForSingleProfile(false) 
      .withHeaderBackground(R.drawable.header1) 
      .addProfiles(
        new ProfileDrawerItem().withName("New User").withIcon(getResources() 
          .getDrawable(R.drawable.profile)) 
      ) 
      .withOnAccountHeaderListener(new AccountHeader.OnAccountHeaderListener() { 
       @Override 
       public boolean onProfileChanged(View view, IProfile profile, boolean currentProfile) { 
        return false; 
       } 
      }) 
      .build(); 

    return headerResult; 

} 

private void CreateDrawer(AccountHeader header, Toolbar toolbar) { 

    PrimaryDrawerItem p_item1 = new PrimaryDrawerItem().withSetSelected(true).withIdentifier(1) 
      .withName(R.string.map).withIcon(FontAwesome.Icon.faw_map); 
    PrimaryDrawerItem p_item2 = new PrimaryDrawerItem().withIdentifier(2) 
      .withName(R.string.analyze_soil).withIcon(FontAwesome.Icon.faw_bullseye); 
    PrimaryDrawerItem p_item3 = new PrimaryDrawerItem().withIdentifier(3) 
      .withName(R.string.drawer_item_statistic).withIcon(FontAwesome.Icon.faw_line_chart); 
    // 
    SecondaryDrawerItem s_item1 = new SecondaryDrawerItem().withIdentifier(4) 
      .withName(R.string.drawer_item_app_settings).withIcon(FontAwesome.Icon.faw_cog); 
    SecondaryDrawerItem s_item2 = new SecondaryDrawerItem().withIdentifier(5) 
      .withName(R.string.drawer_item_account_settings).withIcon(FontAwesome.Icon.faw_cog); 
    SecondaryDrawerItem s_item3 = new SecondaryDrawerItem().withIdentifier(6) 
      .withName(R.string.logout).withIcon(FontAwesome.Icon.faw_sign_out); 

    //Create the drawer and remember the `Drawer` result object 
    result = new DrawerBuilder() 
      .withActivity(this) 
      .withAccountHeader(header) 
      .withToolbar(toolbar) 
      .addDrawerItems(
        p_item2, 
        p_item1, 
        p_item3, 
        new DividerDrawerItem(), 
        s_item1, 
        s_item2, 
        new DividerDrawerItem(), 
        s_item3 
      ) 
      .withOnDrawerItemClickListener(new Drawer.OnDrawerItemClickListener() { 
       @Override 
       public boolean onItemClick(View view, int position, IDrawerItem drawerItem) { 

        int clickedID = (int) drawerItem.getIdentifier(); 
        Intent i; 
        switch (clickedID) { 
         case 1: 
          drawerItem.withSetSelected(false); 
          i = new Intent(MainActivity.this, MapsActivity.class); 
          startActivity(i); 
          break; 
         case 2: 
          drawerItem.withSetSelected(false); 
          i = new Intent(MainActivity.this, AnalyzeSoilActivity.class); 
          startActivity(i); 
          break; 
         case 3: 
          drawerItem.withSetSelected(false); 
          i = new Intent(MainActivity.this, StatisticActivity.class); 
          startActivity(i); 
          break; 
         case 4: 
          drawerItem.withSetSelected(false); 
          i = new Intent(MainActivity.this, AppSettingActivity.class); 
          startActivity(i); 
          break; 
         case 5: 
          drawerItem.withSetSelected(false); 
          i = new Intent(MainActivity.this, AccountSettingActivity.class); 
          startActivity(i); 
          break; 
         case 6: 
          session.logoutUser(); 
          break; 
        } 
        return false; 
       } 
      }) 
      .build(); 
} 

Answer 1

他你好像你正在爲每個活動創建會話實例。嘗試創建單獨的共享首選項類。在這裏，當你調用構造函數

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

的editor.clear（）被調用它，當你達到清除你的喜好主要活動

Answer 2

你必須改變你SessionManager構造如下圖所示：

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

您在編輯器上調用了清除方法，因此每次運行MainActivity時，會話管理器都會首先讀取共享的pref值，然後清除它們。這就像你正在清除值，然後你想要它的數據！

Answer 3

公共類MyPreferences實現AppConstants，VCardStorage {

private static final String TAG = "MyPreferences"; 
private static final String APP_PREFS = "my_prefs"; 

private static MyPreferences mPreferences; 
private SharedPreferences mPreferences; 
private Editor mEditor; 
private Context mContext; 


private MyPreferences(Context context) { 
    mContext = context; 
    mPreferences = context.getSharedPreferences(APP_PREFS, Context.MODE_PRIVATE); 
    mEditor = mPreferences.edit(); 
} 

public static MyPreferences getInstance(Context context) { 
    if (mPreferences == null) { 
     mPreferences = new MyPreferences(context); 
    } 
    return mPreferences; 
} 

public void removeKey(String key) { 
    mEditor.remove(key).apply(); 
} 

public void clear() { 
    mEditor.clear().commit(); 
    ciaoPreferences = null; 
} 

public AppState getAppState() { 
    String state = mPreferences.getString(PREFS_APP_STATE, AppState.INSTALLED.name()); 
    return AppState.valueOf(state); 
} 

public void setAppState(AppState state) { 
    mEditor.putString(PREFS_APP_STATE, state.name()).apply(); 
} 

Answer 4

每次我重新啓動我的應用我的活動將只是回到LoginActivity代替MainActivity

大概是因爲LoginActivity（或SplashActivity）是清單中設置的主要活動。

onCreate中沒有代碼可以在登錄活動按鈕單擊之外啓動MainActivity。實現SharedPreferences不僅僅是爲你做。從構造`;

// top of onCreate 
super.onCreate(savedInstanceState); 
session = new SessionManager(getApplicationContext()); 
boolean loggedIn = session.isLoggedIn() 
Toast.makeText(this, "Login status: " + loggedIn, Toast.LENGTH_LONG).show(); 
if (loggedIn) { 
    // start MainActivity 
    finish(); // don't need this activity 
} else { 
    // load LoginActivity 
} 

---

而且從構造`this.editor.clear（）除去

this.editor.clear();