如何使用SharedPreferences改變視圖知名度登錄和註銷

Question

如何登錄創建SharedPreferences與集可視性如果用戶成功登錄該按鈕將被註銷，登錄將會消失

public class Login extends ActionBarActivity implements View.OnClickListener{ 

    private ProgressDialog pDialog; 
    JSONParser jsonParser = new JSONParser(); 
    private static String url_check_login = ""; 
    private static final String TAG_SUCCESS = "success"; 
    Context cont=this; 
    EditText uname, pword; 
    Boolean nega = false; 
    private Toolbar toolbar; 

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

     toolbar = (Toolbar) findViewById(R.id.app_bar); 
     setSupportActionBar(toolbar); 
     getSupportActionBar().setDisplayHomeAsUpEnabled(true); 

     uname = (EditText) findViewById(R.id.uname); 
     pword = (EditText) findViewById(R.id.pword); 

     Button login = (Button)findViewById(R.id.btnLogin); 
     login.setOnClickListener(this); 
     Button register = (Button)findViewById(R.id.btnRegister); 
     register.setOnClickListener(this); 


    } 

     @Override 
     public void onClick(View v) 
     { 
      final int id = v.getId(); 
      switch (id) { 
       case R.id.btnLogin: 
        new SubmitLogin().execute(); 
        break; 
       case R.id.btnRegister: 
        Intent i = new Intent (this, Registration.class); 
        startActivity(i); 
        finish(); 
        break; 
       // even more buttons here 
      } 
     } 



    class SubmitLogin extends AsyncTask<String, String, String> { 

     @Override 
     protected void onPreExecute() { 
      super.onPreExecute(); 
      pDialog = new ProgressDialog(Login.this); 
      pDialog.setMessage("Logging In ..."); 
      pDialog.setIndeterminate(false); 
      pDialog.setCancelable(true); 
      pDialog.show(); 
     } 

     protected String doInBackground(String... args) { 

      List<NameValuePair> params = new ArrayList<NameValuePair>(); 
      params.add(new BasicNameValuePair("username", uname.getText().toString())); 
      params.add(new BasicNameValuePair("pass", pword.getText().toString())); 
      JSONObject json = jsonParser.makeHttpRequest(url_check_login, "POST", params); 
      Log.d("Create Response", json.toString()); 
      try { 
       int success = json.getInt(TAG_SUCCESS); 
       if (success == 1) { 
        nega = false; 
        SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(getApplicationContext()); 
        SharedPreferences.Editor editor = prefs.edit(); 
        editor.putString("username", uname.getText().toString()); 
        editor.commit(); 
        Intent gotoLogs = new Intent(cont, MainActivity.class); 
        startActivity(gotoLogs); 
        finish(); 
       } else { 
        nega = true; 
       } 
      } catch (JSONException e) { 
       e.printStackTrace(); 
      } 
      return null; 
     } 

     protected void onPostExecute(String file_url) { 
      pDialog.dismiss(); 
      if (nega) { 
       new AlertDialog.Builder(cont) 
         .setTitle("Login Failed") 
         .setMessage("Wrong Username or Password") 
         .setNegativeButton(android.R.string.yes, new DialogInterface.OnClickListener() { 
          public void onClick(DialogInterface dialog, int which) { 

          } 
         }) 
         .setIcon(android.R.drawable.ic_dialog_alert) 
         .show(); 
      } 
     } 
    } 
    @Override 
    public boolean onOptionsItemSelected(MenuItem item) { 
     switch (item.getItemId()) { 

      case android.R.id.home: 
       //Close current activity 
       startActivity(new Intent(this,MainActivity.class)); 
       return true; 

      default: 
       return super.onOptionsItemSelected(item); 
     } 
    } 

} 

Answer 1

要放置信息爲SharedPreferences，你應該寫如下：

SharedPreferences sp = getSharedPreferences(PREFERNCES_FILE, MODE_PRIVATE); 
sp.edit().putString(PREFERENCES_LOGIN, login).apply(); 

變量PREFERNCES_FILE和PREFERENCES_LOGIN應該被定義爲String：

public static final String PREFERNCES_FILE = "my_preferences_file"; 
public static final String PREFERENCES_LOGIN = "login"; 

在註銷應該有：

sp.edit().remove(PREFERENCES_LOGIN).apply(); 

然後檢查是否有媒體鏈接一些信息電話：

boolean isLogged = sp.contains(PREFERENCES_LOGIN); 

然後，只需設置所需的可視性：

login.setVisibility(isLogged ? View.GONE : View.VISIBLE); 

UPDATE

好的，這裏是例子。此代碼應在onCreate：

SharedPreferences sp = getSharedPreferences(PREFERNCES_FILE, MODE_PRIVATE); 
boolean isLogged = sp.contains(PREFERENCES_LOGIN); 
Button login = (Button)findViewById(R.id.btnLogin); 
login.setVisibility(isLogged ? View.GONE : View.VISIBLE); 
login.setOnClickListener(this); 
Button logout = (Button)findViewById(R.id.btnLogout); 
logout.setVisibility(isLogged ? View.VISIBLE : View.GONE); 
logout.setOnClickListener(this); 

而且應該有按鈕，在你的login_user XML與btnLogout ID。 在onClick應該是：

@Override 
    public void onClick(View v) 
    { 
     final int id = v.getId(); 
     switch (id) { 
      case R.id.btnLogin: 
       SharedPreferences sp = getSharedPreferences(PREFERNCES_FILE, MODE_PRIVATE); 
       sp.edit().putString(PREFERENCES_LOGIN, login).apply(); 
       findViewById(R.id.btnLogin).setVisibility(View.GONE); 
       findViewById(R.id.btnLogout).setVisibility(View.VISIBLE); 
       //another actions after login 
       break; 
      case R.id.btnLogout: 
       SharedPreferences sp = getSharedPreferences(PREFERNCES_FILE, MODE_PRIVATE); 
       sp.edit().remove(PREFERENCES_LOGIN).apply(); 
       findViewById(R.id.btnLogin).setVisibility(View.VISIBLE); 
       findViewById(R.id.btnLogout).setVisibility(View.GONE); 
       //another actions after logout 
       break; 
      // even more buttons here 
     } 
    } 

在login變量應登錄數據 - 我不知道，你應該得到它。