问题
I would like to know how to implement splash screen using Navigation Architecture Component.
Till now I have something like this
A user has to setup his profile in ProfileFragment for the first time and can edit their profile from ChatFragment.
My problem is I don't know how to remove SplashFragment from stack after navigation. I've seen conditional navigation but didn't quite understand.
回答1:
There is a common misuse of the splash screen when it is shown to the user for some amount of seconds, and users are wasting their time looking at the Splash screen while they could already interact with the App. Instead of that, you should get them ASAP to the screen where they could interact with the App. Because of that previously Splash screen was considered anti-pattern on android. But then Google realized that there still exist short window between user had clicked on the icon and your first App screen is ready for interaction, and during that time you can show some branding information. This is the right way to implement a Splash screen.
So to implement Splash screen the right way you don't need separate Splash Fragment as it will introduce an unnecessary delay in App loading. To do it you will need only special theme. In theory App theme could be applied to UI and becomes visible much sooner than your App UI will be initialized and become visible. So in a nutshell, you just need SplashTheme like this:
<style name="SplashTheme" parent="Theme.AppCompat.NoActionBar">
<item name="android:windowBackground">@drawable/splash_background</item>
</style>
splash_background drawable should be like this:
<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android"
android:opacity="opaque"> <!-- android:opacity="opaque" should be here -->
<item>
<!--this is your background, you can use color, gradient etc.-->
<color android:color="@color/colorPrimary"/>
<!--<shape>
<gradient
android:angle="315"
android:endColor="#1a82ff"
android:startColor="#2100d3"
android:type="linear"/>
</shape> -->
</item>
<item>
<bitmap android:src="@drawable/ic_logo"
android:gravity="center"/>
</item>
</layer-list>
Your fragments will be anyway hosted in some activity, let's call it MainActivty. In the Manifest just add SplashTheme to your Activity (that will show the splash screen theme from the moment user had clicked the App icon) :
<activity android:name=".ui.MainActivity"
android:theme="@style/SplashTheme">
Then in MainActivity to return to your regular AppTheme do this in onCreate before super call :
override fun onCreate(savedInstanceState: Bundle?) {
setTheme(R.style.AppTheme)
super.onCreate(savedInstanceState)
.....
回答2:
Splash screens have always been weird on Android. You only want to show a splash screen between clicking the app icon and the creation of the first Activity. If your splash screen is a Fragment the user will still see the white background until the first Activity is created and the startup time of your app will increase because a splash Fragment has to be created and removed. The best practice is to use a splash AppTheme like Ian Lake (an Android Framework Engineer) explains in this post.
As for navigation, your app should have a fixed destination which is the first and last screen a user sees when entering and exiting your app like explained in the principles of navigation. In your case it would make sense to make the ChatFragment the fixed destination. In the onCreate of the ChatFragment you should check if the user already has a profile and redirect them to the ProfileFragment using conditional navigation if they don't.
回答3:
You can try this, it currently works for me:
<action
android:id="@+id/action_splashFragment_to_profileFragment"
app:destination="@id/signInFragment"
app:launchSingleTop="true"
app:popUpTo="@id/splashFragment"
app:popUpToInclusive="true" />
Just set the popUpTo(the current destination) and popUpToInclusive(true), this will pop all other screens until it gets to the specified destination - also pop the destination if popUpToInclusive() is set to true - before navigating to the new destination.
回答4:
Here is two way to solve the above situation.
One：
In the NavHostFragment's Activity, override the onBackPress() method,adn if the current NavDestination is MainFragment then just finish() the Activity.
@Override
public void onBackPressed() {
NavDestination navDestination = mNavController.getCurrentDestination();
if (navDestination != null
&& navDestination.getId() == R.id.mainFragment) {
finish();
return;
}
super.onBackPressed();
}
Two:
Set the to MainFragment action in Navigation_graph app:popUpTo="@id/nav_graph" and app:popUpToInclusive="true"
<?xml version="1.0" encoding="utf-8"?>
<navigation
android:id="@+id/nav_graph"
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
app:startDestination="@id/splashFragment">
<fragment
android:id="@+id/splashFragment"
android:name="xxx.fragment.splash.SplashFragment"
android:label="fragment_splash"
tools:layout="@layout/fragment_splash">
<action
android:id="@+id/action_splashFragment_to_mainFragment"
app:destination="@id/mainFragment"
app:enterAnim="@anim/anim_right_in"
app:exitAnim="@anim/anim_left_out"
app:popEnterAnim="@anim/anim_left_in"
app:popExitAnim="@anim/anim_right_out"
app:popUpTo="@id/nav_graph"
app:popUpToInclusive="true"/>
<action
android:id="@+id/action_splashFragment_to_guideFragment"
app:destination="@id/guideFragment"
app:enterAnim="@anim/anim_right_in"
app:exitAnim="@anim/anim_left_out"
app:popEnterAnim="@anim/anim_left_in"
app:popExitAnim="@anim/anim_right_out"
app:popUpTo="@id/nav_graph"
app:popUpToInclusive="true"/>
</fragment>
<fragment
android:id="@+id/guideFragment"
android:name="xxx.fragment.guide.GuideFragment"
android:label="GuideFragment"
tools:layout="@layout/fragment_guide">
<action
android:id="@+id/action_guideFragment_to_mainFragment"
app:destination="@id/mainFragment"
app:enterAnim="@anim/anim_right_in"
app:exitAnim="@anim/anim_left_out"
app:popEnterAnim="@anim/anim_left_in"
app:popExitAnim="@anim/anim_right_out"
app:popUpTo="@id/nav_graph"
app:popUpToInclusive="true"/>
</fragment>
<fragment
android:id="@+id/mainFragment"
android:name="xxx.fragment.main.MainFragment"
android:label="fragment_main"
tools:layout="@layout/fragment_main">
</fragment>
</navigation>
Wish for help!
Warning：this is deprecated. In Navigation alpha08, the clearTask tag is removed:Remove the deprecated clearTask and launchDocument flags from NavOptions
In my project, I test app:clearTask="true" in the action,and it works well.~~~
<fragment
android:id="@+id/splashFragment"
android:name="xxx.SplashFragment"
android:label="fragment_splash"
tools:layout="@layout/fragment_splash">
<action
android:id="@+id/action_splashFragment_to_mainFragment"
app:destination="@id/mainFragment"
app:enterAnim="@anim/anim_right_in"
app:exitAnim="@anim/anim_left_out"
app:popEnterAnim="@anim/anim_left_in"
app:popExitAnim="@anim/anim_right_out"
app:clearTask="true"/>
</fragment>
回答5:
You can try this trick it's woking absolutely fine for me. Make your splash screen as launcher screen from the manifest file and start your host activity form the splash screen.
Manifest file code
<activity android:name=".SplashScreen"
android:theme="@style/Theme.AppCompat.Light.NoActionBar">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
In your java file
new Handler().postDelayed(new Runnable(){
@Override
public void run() {
/* Create an Intent that will start the Navigation host activity . */
Intent mainIntent = new Intent(getApplicationContext(), MainActivity.class);
startActivity(mainIntent);
finish();
}
}, 5000);
Xml code of your host activity
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<fragment
android:id="@+id/nav_host_fragment"
android:name="androidx.navigation.fragment.NavHostFragment"
android:layout_width="0dp"
android:layout_height="0dp"
app:defaultNavHost="true"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:navGraph="@navigation/navigation_graph" />
</android.support.constraint.ConstraintLayout>
And you navigation will be like this
<?xml version="1.0" encoding="utf-8"?>
<navigation xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/navigation_graph"
app:startDestination="@id/homeFragment">
<fragment
android:id="@+id/homeFragment"
android:name="com.devgenesis.breaker.ice.navigationmproject.HomeFragment"
android:label="fragment_home"
tools:layout="@layout/fragment_home" />
</navigation>
来源：https://stackoverflow.com/questions/51189835/navigation-architecture-component-splash-screen