Question

我很难让用户在退出后使用后退按钮离开我的应用。

我的HomeActivity检查用户是否有sessionID。如果他们不这样做，它会将他们重定向到登录页面。成功登录后，将显示主页，显示sessionID和注销按钮。

单击该按钮将删除会话ID，并向用户显示该消息。此时按下后退按钮会将用户带到登录页面，我无法通过按下来退出 - 我可以登录并按回去退出应用程序，但我无法退出注销后返回按钮。

任何想法？

HomeActivity

public class HomeActivity extends Activity {
protected void onCreate(Bundle savedInstanceState){
    super.onCreate(savedInstanceState);
}

protected void onStart(){
    super.onStart();
    /*
     * Check if a session ID exists - if it does then display the home screen 
     * If the session ID does not exist then redirect the user to the login page.
     */
    String sessionId = Session.getSessionId(getApplicationContext());
    if (StringUtils.isBlank(sessionId)){
        navigateToLoginActivity();
    }

    // Display the Home Screen
    setContentView(R.layout.home);

    TextView tv = (TextView)findViewById(R.id.welcome);

    tv.setText(sessionId);
}

public void logout(View view){
    navigateToLogoutActivity();
}

public void navigateToLoginActivity(){
    Intent loginIntent = new Intent(getApplicationContext(),LoginActivity.class);
    loginIntent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
    startActivity(loginIntent);
}

public void navigateToLogoutActivity(){
    Intent logoutIntent = new Intent(getApplicationContext(),LogoutActivity.class);
    logoutIntent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
    startActivity(logoutIntent);
}
}

LoginActivity

public class LoginActivity extends Activity {
EditText nfcET;

protected void onCreate(Bundle savedInstanceState){
    super.onCreate(savedInstanceState);
    setContentView(R.layout.login);
    nfcET = (EditText)findViewById(R.id.nfckey);
}

public void login(View view){
    String nfckey = nfcET.getText().toString();
    RequestParams params = new RequestParams();
    params.put("nfckey", nfckey);
    invokeWS(params);
}

public void invokeWS(RequestParams params){
   // REMOVED WEBSERVICE CODE - calls webservice and retrieves a sessionID which is saved in a SharedPreference, it calls navigateToHomeActivity upon successful login


}

public void navigatetoHomeActivity(){
    Intent homeIntent = new Intent(getApplicationContext(),HomeActivity.class);
    homeIntent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
    startActivity(homeIntent);
}
}

LogoutActivity

public class LogoutActivity extends Activity{
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        Session.removeSessionId(getApplicationContext());

        if (!StringUtils.isBlank(Session.getSessionId(getApplicationContext()))){
            //TODO - Handle the case that the session was not removed!
        } else {
            setContentView(R.layout.logout);
        }
    }
}

Answer 1

这是你遇到困难的部分：

if (StringUtils.isBlank(sessionId)){
        navigateToLoginActivity();
}

每当您需要通过单击后退按钮退出应用程序时，它就是最后一次访问的主页。并且因为主页将始终检查您是否已登录，并且在后者的情况下将您重定向到登录页面，您真的被困住并且是实时的;）

覆盖按键事件：

@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
    switch(keyCode){
    case KeyEvent.KEYCODE_BACK:
        // do something here 
        // Here you can put your boolean variable
          isOutOfApp = true;
        return true;
    }
    return super.onKeyDown(keyCode, event);
}

这里可以做到：

if (StringUtils.isBlank(sessionId)){
        if(isOutOfApp) {
           // show a confirmation message 
           // and out of the app
        } else {
           navigateToLoginActivity();
        } 
}

Answer 2

要离开循环，请让LoginActivity登录并使用startActivtyForResult返回是否成功：

在HomeActivity中：

将navigateToLoginActivity更改为如下所示：

public void navigateToLoginActivity(){
    Intent loginIntent = new Intent(getApplicationContext(),LoginActivity.class);
    startActivityForResult(loginIntent, REQ_LOG_IN);
}

在LoginActivity中：

将此添加到您的onCreate：

setResult(RESULT_CANCELED);

将您的navigationtoHomeActivity更改为：

public void navigatetoHomeActivity(){
    setResult(RESULT_OK);
    finish();
}

返回HomeActviity：

将此块移动到onResume（）（因为在onResume之前调用onActivityResult）

    /*
     * Check if a session ID exists - if it does then display the home screen 
     * If the session ID does not exist then redirect the user to the login page.
     */
    String sessionId = Session.getSessionId(getApplicationContext());
    if (StringUtils.isBlank(sessionId)){
        navigateToLoginActivity();
    }

添加此方法：

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {

    if(requestCode == REQ_LOGIN && resultCode == RESULT_CANCELED){
        finish();
    }

}

由于重定向，无法使用后退按钮离开Android应用

2 个答案: