Question

我能够打开应用程序，然后打开登录界面，登录后会转到MainActivity。从MainActivity开始没有返回登录，它将一直保持在会话中直到注销。但是当我退出应用程序时，它会返回到登录屏幕，即使我有一个Sharedpref来保存会话中的用户名。我在nohistory=true中添加了manifest。在MainActivity我放置了Intent mainactivity.class（如果按回按钮），这个原因是因为当我：

logout > login > mainactivity

然后按回按钮它将返回登出屏幕（由于myhistory=true，登录应该没问题）。我的问题是即使应用退出，如何在会话中保留用户名。

以下链接对我没什么帮助

What is the correct way of creating a login screen/activity in Android?

Prevent showing Login screen after user login

How to presist Login credentials and do auto-login in Android

我的代码

LOGIN.java

    public class Login extends Activity {
    private EditText etUsername;
    private Button btnLogin;
    private Button btnCancel;
    private TextView lblResult;

    @Override  
    public boolean onKeyDown(int keyCode, KeyEvent event)  
    {          
        if(keyCode==KeyEvent.KEYCODE_BACK)  
        {             
            this.startActivity(new Intent(Login.this,Login.class));  
        }  
        return true;  
    }  
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.login);

        btnLogin.setOnClickListener(new OnClickListener() {
            public void onClick(View v) {
            String username = etUsername.getText().toString();

            SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(getApplicationContext());
            SharedPreferences.Editor editor = prefs.edit();
            editor.putString("username", username);

            if(username.equals("1111")){
                lblResult.setText("Login successful.");

             Intent i = new Intent(getApplicationContext(), MainActivity.class);
                startActivity(i);

Logout.java

    public class LogoutActivity extends Activity {
    private Button btnLogout;
    private Button btnCancel;
    private TextView lblResult;
    private EditText code;
    @Override  
    public boolean onKeyDown(int keyCode, KeyEvent event)  
    {  
       if(keyCode==KeyEvent.KEYCODE_BACK)  
        {  
            this.startActivity(new Intent(LogoutActivity.this,MainActivity.class));  
        }  
        return true;  
    }  

    @Override
    public void onCreate(Bundle savedInstanceState) { 
        super.onCreate(savedInstanceState);
        setContentView(R.layout.logout);

        code = (EditText)findViewById(R.id.codeout);
        btnLogout = (Button) findViewById(R.id.submit);
        btnCancel = (Button) findViewById(R.id.cancel);
        lblResult = (TextView)findViewById(R.id.result);

        btnLogout.setOnClickListener(new OnClickListener(){

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                String logout = code.getText().toString();

                SharedPreferences settings = PreferenceManager.getDefaultSharedPreferences(getApplicationContext());
                SharedPreferences.Editor editor = settings.edit();
                editor.remove("username");

                if (logout.equals("99999")){
                    lblResult.setText("Logout successful");

                    Intent i = new Intent(getApplicationContext(), Login.class);
                    startActivity(i);
                } else {
                    lblResult.setText("Logout failed");

                }

            }
        });

         btnCancel.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {

                Intent i = new Intent(getApplicationContext(), MainActivity.class);
                startActivity(i);

            }

    });

Answer 1

在Login.onCreate()中，检查SharedPref中的用户ID。如果存在，请直接转到MainActivity。

Answer 2

我在应用程序的启动画面用户注销时是否有解决方案检查，然后进入登录屏幕或主屏幕

String unique_id = loginSharedPreferences
                        .getString("UniqueId", "NA");

if (unique_id.equals("")) {
    Intent intent = new Intent(Splace_Screen.this,
                                    LoginActivity.class);
    startActivity(intent);

} else {
   Intent intent = new Intent(Splace_Screen.this,
                                    DrawerActivity.class);
   startActivity(intent);
}
finish();

Android：使用noHistory和SharePrefs的登录屏幕，但在退出应用程序后，它会返回登录屏幕

2 个答案: