用户在Android Studio中登录后如何打开应用程序进行其他活动

Question

I'm very new to Android Studio and I'm making a simple app where the user has to login and it goes to a different screen. When the user first opens up the app they will be prompted with a login activity and if login successful they will move onto another activity. I want to know how after the user logins and then shuts down the app and opens it again it will take them directly to the other activity.

Answer 1

You need something like this in your login activity:

protected void onResume() {
    super.onResume();
    // Checking for user session
    // if user is already logged in, take him to main activity
    if (pref.isLoggedIn()) {
       //here, pref is the instance of your preference manager
        Intent intent = new Intent(LoginActivity.this, MainActivity.class);
        intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TOP);
        startActivity(intent);

        finish();
    }

}

You may create a preference manager like this:

public class PrefManager {
// Shared Preferences
SharedPreferences pref;

// Editor for Shared preferences
SharedPreferences.Editor editor;

// Context
Context _context;

// Shared pref mode
int PRIVATE_MODE = 0;

// Shared preferences file name
private static final String PREF_NAME = "YourAppName";

// All Shared Preferences Keys
private static final String KEY_IS_LOGGED_IN = "isLoggedIn";
private static final String KEY_NAME = "name";
private static final String KEY_PICTURE = "picture";
private static final String KEY_MOBILE = "mobile";

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

public void setMobileNumber(String mobileNumber) {
    editor.putString(KEY_MOBILE, mobileNumber);
    editor.commit();
}

public void setName(String name) {
    editor.putString(KEY_NAME, name);
    editor.commit();
}

public void setPicture(String picture) {
    editor.putString(KEY_PICTURE, picture);
    editor.commit();
}

public String getMobileNumber() {
    return pref.getString(KEY_MOBILE, null);
}

//Logging in user and setting the name and profile picture
public void createLogin(final String mobile) {

    //here, handle the mobile number or email or any details that you 
    //use for the login. Then do this:

    editor.putBoolean(KEY_IS_LOGGED_IN, true);
    editor.commit();
}

public boolean isLoggedIn() {
    return pref.getBoolean(KEY_IS_LOGGED_IN, false);//false is the default value in case there's nothing found with the key
}

public void clearSession() {
    editor.clear();
    editor.commit();
}
}

In the login activity, also set the login in the PrefManager to true once your login has succeeded. Let me know if you need any more help.

Answer 2

Splash screen is the best place to decide to which page the user should have to be navigated. In splash screen, check weather the user already logged in. If logged in then navigate him to home page. Else navigate him to login/signup page. Store the user login information in shared preferences to check on splash screen.

Answer 3

In a very simple way,Store the user's login details using Shared Preference. And before login check if the shared preference has user credentials.If it has, switch to another activity else go to login page.

Answer 4

When user first open app, when login success then you save a variable boolean isLogin is true to Shared Preference. When open again, You check variable boolean isLogin is true then start MainActivity,vice versa you start Activity Login.