JetPack - - - Navigation

1.Navigation The birth of

Activity Nesting multiple Fragment Of UI Architectural patterns are already very common , But yes. Fragment It has been a troublesome thing to manage . We need to pass FragmentManager and FragmentTransaction To manage Fragment Switch between . The switching of pages usually also includes the application Appbar Management of 、Fragment Switching between animations , as well as Fragment Parameter transfer between . Pure code is not particularly friendly to use , also Fragment and Appbar In the process of management and use Appear confused .
So ,Jetpack Provides Navigation Components , For our convenience Manage pages and AppBaro.

2.Navigation The advantages of

1. Visual page navigation map , Be similar to AppleXcode Medium StoryBoard, It is convenient for us to clarify the page relationship .
2. adopt destination and action Complete the navigation between pages .
3. Easy to add page switching animation .
4. Type safe parameter passing between pages .
5. adopt NavigationUl, On the menu 、 Bottom navigation 、 Drawer menu navigation for unified management .
6. Support deep links DeepLinko

3.Navigation The main elements of

NavigationGraph, A new kind of XML Resource file , Contains all the pages of the application , And between pages
Relationship .
NavHostFragment, A special Fragment, You can think of it as something else Fragment The container of ,NavigationGraph Medium Fragment It is through NavHostFragment On display .
NavController, Used to complete... In code NavigationGraph Specific page switching work in .
The relationship between their three responsibilities ．

When you want to switch Fragment when , Use NavController object , Tell it you want to go NavigationGraph Which of them? Fragment,NavContr011er Will you want to go Fragment Exhibition NavHostFragment in .

4.Navigation application

First, add dependencies ：

  implementation 'androidx.navigation:navigation-fragment:2.3.5'
  implementation 'androidx.navigation:navigation-ui:2.3.5'

And then res Folder Create Navigation Folder , And then create the XML file .

<androidx.constraintlayout.widget.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/fragment"
        android:name="androidx.navigation.fragment.NavHostFragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:defaultNavHost="true"
        app:navGraph="@navigation/my_pager"
        tools:layout_editor_absoluteX="1dp"
        tools:layout_editor_absoluteY="1dp" />

</androidx.constraintlayout.widget.ConstraintLayout>

This is MainActivity Of Xml file , adopt XML add to NavHostFragment.

• android:name  Attribute contains  NavHost  The name of the implemented class .

• app:navGraph  Property will be  NavHostFragment  Associated with the navigation map . The navigation map will be here  NavHostFragment  Specify all destinations that users can navigate to .
• app:defaultNavHost="true"  Properties ensure that your  NavHostFragment  Will intercept the system return button . Please note that , There can only be one default  NavHost. If the same layout （ for example , Double pane layout ） There are multiple hosts in , Be sure to specify only one default  NavHost.

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        // obtain navController
        NavController navController = Navigation.findNavController(this, R.id.fragment);
        // Set up ActionBar
        NavigationUI.setupActionBarWithNavController(this,navController);
    }
}

<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/my_pager"
    app:startDestination="@id/homeFragment">


    <fragment
        android:id="@+id/homeFragment"
        android:name="com.example.navigtion.HomeFragment"
        android:label="fragment_home"
        tools:layout="@layout/fragment_home" >
        <action
            android:id="@+id/action_homeFragment_to_blankFragment"
            app:destination="@id/blankFragment" />
        <argument
            android:name="user_name"
            app:argType="string"
            android:defaultValue="unknown"
            />
        <argument
           android:name="age"
            app:argType="integer"
            android:defaultValue="0"
            />
    </fragment>
    <fragment
        android:id="@+id/blankFragment"
        android:name="com.example.navigtion.BlankFragment"
        android:label="fragment_blank"
        tools:layout="@layout/fragment_blank" >
        <action
            android:id="@+id/action_blankFragment_to_homeFragment"
            app:destination="@id/homeFragment" />
    </fragment>
</navigation>

This is my_pager, Namely Navigation Navigation files for .

navigation Under the label ：

  app:startDestination Set the starting point fragment

fragment Under the label ：

  android:name fragment The location of the file

  tools:layout fragment Of Xml file

action Under the label ：

  app:destination action Destination

argument Under the label ：

  android:name  The attribute name
  app:argType    Attribute types
  android:defaultValue  The default value is

public class HomeFragment extends Fragment {


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_home, container, false);
    }

    @Override
    public void onActivityCreated(@Nullable Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        Button button = getView().findViewById(R.id.button);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Bundle bundle = new HomeFragmentArgs.Builder()
                        .setUserName(" Xiaohua ")
                        .setAge(12)
                        .build()
                        .toBundle();

                // Pass value ,  It can also be used here or not my_pager The configuration in the file can be used directly Arguments Transfer values and then take values like this    Bundle bundle = new Bundle();
                //                    bundle.putString("user_name"," Xiaohua ");
                //                    bundle.putInt("age",12);
                //                     navController.navigate(R.id.action_homeFragment_to_blankFragment,bundle);
                NavController navController = Navigation.findNavController(v);
                // Execute this action Event and pass value 
                navController.navigate(R.id.action_homeFragment_to_blankFragment,bundle);
            }
        });
    }
}

public class BlankFragment extends Fragment {


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_blank, container, false);
    }


    @Override
    public void onActivityCreated(@Nullable Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        // Value ,  It can also be used here or not my_pager The configuration in the file can be used directly Arguments Transfer values and then take values like this   age = getArguments().getInt("age");
        HomeFragmentArgs homeFragmentArgs = HomeFragmentArgs.fromBundle(getArguments());
        String userName = homeFragmentArgs.getUserName();
        int age = homeFragmentArgs.getAge();
        Log.i("ning",userName+"   "+age);
        Button button = getView().findViewById(R.id.button);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                NavController navController = Navigation.findNavController(v);
                // Execute this action event 
                navController.navigate(R.id.action_blankFragment_to_homeFragment);
            }
        });
    }
}

Effect demonstration ：

        

5.Navigation stay app Bar And menu Application in

<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/my_graph"
    app:startDestination="@id/mainFragment"
    >

    <fragment
        android:id="@+id/mainFragment"
        android:name="com.example.navigtion2.MainFragment"
        android:label="fragment_main"
        tools:layout="@layout/fragment_main" />
    <fragment
        android:id="@+id/settingsFragment"
        android:name="com.example.navigtion2.SettingsFragment"
        android:label="fragment_settings"
        tools:layout="@layout/fragment_settings"

        >
      

    </fragment>

</navigation>

Navigation Navigation Xml file .

<menu xmlns:android="http://schemas.android.com/apk/res/android">
 <!-- there id Want to be with navigation The target in the file  fragment id Agreement -->
 <item android:id="@+id/settingsFragment"  android:title=" This interface "/>
</menu>

Upper right corner menu The configuration file .

public class MainActivity extends AppCompatActivity {
    private NavController navController;
    private AppBarConfiguration appBarConfiguration;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        navController = Navigation.findNavController(this, R.id.fragment);
        // establish appBar
        appBarConfiguration = new AppBarConfiguration.Builder(navController.getGraph()).build();
        // binding 
        NavigationUI.setupActionBarWithNavController(this,navController, appBarConfiguration);
    }

    // Set the menu in the upper right corner 
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        super.onCreateOptionsMenu(menu);
        getMenuInflater().inflate(R.menu.menu_setting,menu);
        return true;
    }

    @Override// Click on the monitor menu 
    public boolean onOptionsItemSelected(@NonNull MenuItem item) {
        return NavigationUI.onNavDestinationSelected(item,navController) || super.onOptionsItemSelected(item);
    }

    @Override // Back to previous page 
    public boolean onSupportNavigateUp() {
        return  NavigationUI.navigateUp(navController,appBarConfiguration)||super.onSupportNavigateUp();
    }
}

The main methods focus on activity in .

public class MainFragment extends Fragment {

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_main, container, false);
    }
}

public class SettingsFragment extends Fragment {

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        setHasOptionsMenu(true);
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_settings, container, false);
    }
}

Effect demonstration ：

        

5.Pendinglntent( Notice jump ) The way

public class MainFragment extends Fragment {

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_main, container, false);
    }

    @Override
    public void onActivityCreated(@Nullable Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        Button button = getView().findViewById(R.id.button);

        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                setNotification();
            }
        });
    }
    
    private void setNotification() {
        if (Build.VERSION.SDK_INT>=Build.VERSION_CODES.O){
            NotificationChannel myChannel = new NotificationChannel(getActivity().getPackageName(), "MyChannel", NotificationManager.IMPORTANCE_DEFAULT);
            myChannel.setDescription("my");
            NotificationManager systemService = getActivity().getSystemService(NotificationManager.class);
            systemService.createNotificationChannel(myChannel);
        }
        Notification build = new NotificationCompat.Builder(getActivity(), getActivity().getPackageName())
                .setContentTitle("Deep Link")
                .setContentText(" Let me try ")
                .setSmallIcon(R.drawable.ic_launcher_background)
                .setDefaults(NotificationCompat.PRIORITY_DEFAULT)
                .setContentIntent(getPendingIntent())
                .build();
        NotificationManagerCompat from = NotificationManagerCompat.from(getActivity());
        from.notify(1,build);

    }

    private PendingIntent getPendingIntent() {
        // Pass value 
        Bundle bundle = new Bundle();
        bundle.putString("name","xiaohua");
        return Navigation.findNavController(getActivity(),R.id.button)
            .createDeepLink()
            .setGraph(R.navigation.my_graph)
            .setDestination(R.id.settingsFragment)
            .setArguments(bundle)
            .createPendingIntent();

    }
}

Effect demonstration ：

                

6.URI Jump

 <fragment
        android:id="@+id/settingsFragment"
        android:name="com.example.navigtion2.SettingsFragment"
        android:label="fragment_settings"
        tools:layout="@layout/fragment_settings"
        >
        <deepLink app:uri="www.xiaohua.com/{param}"/>

    </fragment>

adopt deepLink Label configuration URI.

   <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
            <nav-graph android:value="@navigation/my_graph"/>
        </activity>

Configure the navigation map file in the manifest file .