Firebase Android自动登录 [英] Firebase Android Auto Login

问题描述

所以我设置了电子邮件/密码注册和登录.

So I setup email/password register and login.

那很好.我以为Firebase会解决这个问题，但显然没有. 我希望在用户关闭应用程序后，下次打开应用程序时已经登录.

That is working. I thought Firebase took care of this but apparently not. I want, after the user closes the app, to be logged in already next time they open the app.

缺少什么?

class LoginActivity : AppCompatActivity(){
    lateinit var auth: FirebaseAuth
    lateinit var user: FirebaseAuth

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_login)

        auth = FirebaseAuth.getInstance()
    }

    fun loginLoginClicked(view: View) {
        // Perform login

        val email = loginEmailTxt.text.toString()
        val password = loginPasswordTxt.text.toString()

        auth.signInWithEmailAndPassword(email, password)
                .addOnSuccessListener {
                    finish()
                }
                .addOnFailureListener { exception ->
                    Log.e("Exception", "Could not sign in user - ${exception.localizedMessage}")
                }
        val loginIntent = Intent(this, MainActivity::class.java)
        startActivity(loginIntent)
    }

    fun loginCreateClicked(view: View) {
        // segue to the create user activity

        val createIntent = Intent(this, SignUpActivity::class.java)
        startActivity(createIntent)
    }}
}

推荐答案

Firebase身份验证会自动记住身份验证状态，因此在重新启动应用程序时仍将对用户进行身份验证.

Firebase Authentication does automatically remember authentication state, so the user will still be authenticated when the app is restarted.

但是，如果您的LoginActivity是启动器活动，那么您仍将进入该活动，因此您需要检查用户是否在onCreate()中通过了身份验证，然后将其重定向到您的MainActivity如果他们已经登录，则类似:

However, if your LoginActivity is the launcher activity, you'll still land on this activity, so you'll need to check whether the user is authenticated in onCreate(), and then redirect them to your MainActivity if they are already logged in, something like:

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_login);

    auth = FirebaseAuth.getInstance();

    if (auth.getCurrentUser() != null) {
        // User is signed in (getCurrentUser() will be null if not signed in)
        val intent = Intent(this, MainActivity::class.java);
        startActivity(intent);
        finish();
    }
}

这利用了

This makes use of the FirebaseAuth#getCurrentUser() method that will return a FirebaseUser object if the user is logged in, or null if they are not logged in.

或者，您也可以交换它，以使MainActivity是启动程序活动，然后仅在用户未登录时才显示LoginActivity.

Alternatively, you could swap it around so that the MainActivity is the launcher activity and then only show your LoginActivity if the user is not logged in.

....

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