Jetpack之Navigation(1)

def nav_version = "2.3.2"
// Java language implementation

implementation "androidx.navigation:navigation-fragment:$nav_version"

implementation "androidx.navigation:navigation-ui:$nav_version"
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<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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"
android:orientation="vertical"
tools:context=".MainActivity">
<!--

    app:defaultNavHost="true"

    拦截系统back键

    -->
<androidx.fragment.app.FragmentContainerView
android:id="@+id/my_nav_host_fragment"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="9"
android:name="androidx.navigation.fragment.NavHostFragment"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:defaultNavHost="true"
app:navGraph="@navigation/nav_graph_main"/>

</LinearLayout>
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在res/navigation目录下nav_graph_main.xml

<?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/nav_graph_main.xml"
app:startDestination="@id/page1Fragment">
<fragment
android:id="@+id/page1Fragment"
android:name="com.example.lsn4_navigationdemo.MainPage1Fragment"
android:label="fragment_page1"
tools:layout="@layout/fragment_main_page1">

<!--action:程序中使用id跳到destination对应的类-->
<action
android:id="@+id/action_page2"
app:destination="@id/page2Fragment" />
</fragment>

<fragment
android:id="@+id/page2Fragment"
android:name="com.example.lsn4_navigationdemo.MainPage2Fragment"
android:label="fragment_page2"
tools:layout="@layout/fragment_main_page2">
<action
android:id="@+id/action_page1"
app:destination="@id/page1Fragment" />
<action
android:id="@+id/action_page3"
app:destination="@id/page3Fragment" />
</fragment>

<!--    <navigation-->
<!--        android:id="@+id/nav_graph_page3"-->
<!--        app:startDestination="@id/page3Fragment">-->
<fragment
android:id="@+id/page3Fragment"
android:name="com.example.lsn4_navigationdemo.MainPage3Fragment"
android:label="fragment_page3"
tools:layout="@layout/fragment_main_page3"

        >
<action
android:id="@+id/action_page2"
app:destination="@id/page2Fragment"/>
</fragment>


</navigation>
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//方式一：直接跳入指定的fragment

Navigation.findNavController(view).navigate(R.id.page2Fragment);  

//方式二：通过action

Navigation.findNavController(view).navigate(R.id.action_page2);   //跳入page2
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//获取controller方式一

NavController controller=Navigation.findNavController(this,R.id.my_nav_host_fragment);

//获取controller方式二

NavHostFragment navHostFragment = (NavHostFragment) getSupportFragmentManager().findFragmentById(R.id.my_nav_host_fragment);

NavController controller = navHostFragment.getNavController();

//跳转

controller.navigate(R.id.page2Fragment);
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除了在Activity的布局中指定navigation布局资源以外，还可以通过java代码进行设置

public class MainActivity extends AppCompatActivity {


@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

//方式一

        val finalHost = NavHostFragment.create(R.navigation.nav_graph_main)

        supportFragmentManager.beginTransaction()

                .replace(R.id.ll_fragment_navigation, finalHost)

                .setPrimaryNavigationFragment(finalHost)

                .commit();

    }

//方式二
@Override
public boolean onSupportNavigateUp() {

        Fragment fragment = getSupportFragmentManager().findFragmentById(R.id.my_nav_host_fragment);
return NavHostFragment.findNavController(fragment).navigateUp();

    }

}
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引入底部导航控件

implementation 'com.google.android.material:material:1.1.0'

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布局

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout 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"

    android:orientation="vertical"

    tools:context=".MainActivity">

    <!--

    app:defaultNavHost="true"

    拦截系统back键

    -->

    <androidx.fragment.app.FragmentContainerView

        android:id="@+id/my_nav_host_fragment"

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:layout_weight="9"

        android:name="androidx.navigation.fragment.NavHostFragment"

        app:layout_constraintBottom_toBottomOf="parent"

        app:layout_constraintLeft_toLeftOf="parent"

        app:layout_constraintRight_toRightOf="parent"

        app:layout_constraintTop_toTopOf="parent"

        app:defaultNavHost="true"

        app:navGraph="@navigation/nav_graph_main"/>


    <com.google.android.material.bottomnavigation.BottomNavigationView

        android:id="@+id/nav_view"

        android:layout_width="match_parent"

        android:layout_weight="1"

        android:layout_height="wrap_content"

        app:itemTextColor="#ff0000"

        app:menu="@menu/menu"/>


</LinearLayout>

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menu

<?xml version="1.0" encoding="utf-8"?>

<menu xmlns:android="http://schemas.android.com/apk/res/android">

    <item

        android:id="@+id/page1Fragment"

        android:icon="@drawable/ic_launcher_foreground"

        android:title="1"/>

    <item

        android:id="@+id/page2Fragment"

        android:icon="@drawable/ic_launcher_foreground"

        android:title="2"/>

    <item

        android:id="@+id/page3Fragment"

        android:icon="@drawable/ic_launcher_foreground"

        android:title="3"/>


</menu>

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Activity绑定导航

public class MainActivity extends AppCompatActivity {


    BottomNavigationView bottomNavigationView;


    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        findViewById(R.id.action_page1);

        bottomNavigationView=findViewById(R.id.nav_view);


        //获取controller方式一

        //NavController controller=Navigation.findNavController(this,R.id.my_nav_host_fragment);


        //获取controller方式二

        NavHostFragment navHostFragment = (NavHostFragment) getSupportFragmentManager().findFragmentById(R.id.my_nav_host_fragment);

        NavController controller = navHostFragment.getNavController();


        //绑定导航

        NavigationUI.setupWithNavController(bottomNavigationView,controller);


}