问在Android中创建登录屏幕/活动的正确方式是什么？

EN

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
package="com.example.android">

<-- Permissions etc -->

<application
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name">

    <activity
        android:name=".onboarding.StartupActivity"
        android:label="@string/app_name"
        android:launchMode="singleInstance"
        android:theme="android:style/Theme.NoDisplay">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>

    <activity
        android:name=".MainActivity"
        android:label="@string/app_name"
        android:launchMode="singleTop" />

    <activity
        android:name=".authentication.controller.AuthenticationActivity"
        android:label="@string/title_sign_in"
        android:launchMode="singleTask"
        android:windowSoftInputMode="adjustResize|stateHidden" />

    <-- Other activities, services, etc -->
</application>

package com.example.android.onboarding;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;

import com.example.android.MainActivity;

import com.example.android.authentication.controller.AuthenticationActivity;

import com.example.android.util.ResourceUtils;

public class StartupActivity extends Activity {
    private static final AUTHENTICATION_REQUEST_CODE = 1000;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        if (isLoggedIn()) {
            Intent startupIntent = new Intent(this, MainActivity.class);
            startupIntent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK | Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TOP);
            startActivity(startupIntent);
            finish();
        } else {
            Intent startupIntent = new Intent(this, AuthenticationActivity.class);
            startActivityForResult(startupIntent, AUTHENTICATION_REQUEST_CODE);
        }

        super.onCreate(savedInstanceState);
    }

    private boolean isLoggedIn() {
        // Check SharedPreferences or wherever you store login information
        return this.getSharedPreferences("my_app_preferences", Context.MODE_PRIVATE).getBoolean("loggedIn", false);
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (requestCode == AUTHENTICATION_REQUEST_CODE && resultCode == Activity.RESULT_OK) {
            Intent startupIntent = new Intent(this, MainActivity.class);
            startupIntent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK | Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TOP);
        startActivity(startupIntent);
        }

        finish();
    }
}