android开发分享Android Navigation 使用总结

1.导包

implementation ‘androidx.navigation:navigation-fragment-ktx:2.3.1’
implementation ‘androidx.navigation:navigation-ui-ktx:2.3.1’

2.1 建立 Navigation 入口

在Activity布局文件中建立Fragmeng，必须位NavHostFragment

    <fragment         android:id="@+id/nav_register_frag"         android:fitsSystemWindows="true"      	android:name="androidx.navigation.fragment.NavHostFragment"         android:layout_width="match_parent"         app:defaultNavHost="true"         android:layout_height="match_parent"         app:navGraph="@navigation/nav_register" /> 

• app:defaultNavHost="true"
  设置 Navigation的返回模式，true表明Fragment之间按返回键 返回上一个Fragment；false 表示直接退出Activity。
• app:navGraph="@navigation/nav_register"
  指定的 Navigation xml 文件。

2.2 新建 Navigation xml

<?xml version="1.0" encoding="utf-8"?> <navigation xmlns:android="https://schemas.android.com/apk/res/android"     xmlns:app="https://schemas.android.com/apk/res-auto"     xmlns:tools="https://schemas.android.com/tools"     android:id="@+id/nav_register"     app:startDestination="@id/enterPhoneFragment">      <fragment         android:id="@+id/enterPhoneFragment"         android:name="com.pqtel.pqsecuritysaw.ui.reg.EnterPhoneFragment"         android:label="EnterPhoneFragment"         tools:layout="@layout/frag_enter_phone">         <action             android:id="@+id/action_enterPhoneFragment_to_enterCodeFragment"             app:destination="@id/enterCodeFragment" />     </fragment>     <fragment         android:id="@+id/enterCodeFragment"         android:name="com.pqtel.pqsecuritysaw.ui.reg.EnterCodeFragment"         android:label="EnterCodeFragment"         tools:layout="@layout/frag_enter_code">         <action             app:popUpTo="@id/enterCodeFragment"             app:popUpToInclusive="true"             android:id="@+id/action_enterCodeFragment_to_enterPwdFragment"             app:destination="@id/enterPwdFragment" />     </fragment>     <fragment         android:id="@+id/enterPwdFragment"         android:name="com.pqtel.pqsecuritysaw.ui.reg.EnterPwdFragment"         android:label="EnterPwdFragment"         tools:layout="@layout/frag_enter_pwd" /> </navigation> 

• app:startDestination="@id/enterPhoneFragment"
  主入口，也就是首页面必须指定 否则报错。
• app:destination="@id/enterCodeFragment"
  Action 跳转动作 跳转的目的Fragment
• app:popUpTo="@id/enterCodeFragment"
  app:popUpToInclusive="true"
  一般一起使用如果设置了app:defaultNavHost="true"
  理论上的跳转A-B-C，按下返回时候是C-B-A
  若B到C的Action设置了这两条属性，则返回变成了C-A，B被出栈了。
  

2.3 BottomNavigation与Navigation

可以用此组合替代 viewpager和Tablayout
activity.xml

 <com.google.android.material.bottomnavigation.BottomNavigationView         android:id="@+id/nav_view"         android:layout_width="0dp"         android:layout_height="wrap_content"         android:layout_marginStart="0dp"         android:layout_marginEnd="0dp"         android:background="?android:attr/windowBackground"         app:layout_constraintBottom_toBottomOf="parent"         app:layout_constraintLeft_toLeftOf="parent"         app:layout_constraintRight_toRightOf="parent"         app:menu="@menu/bottom_nav_menu" />      <fragment         android:id="@+id/nav_host_fragment"         android:name="androidx.navigation.fragment.NavHostFragment"         android:layout_width="match_parent"         android:layout_height="match_parent"         app:defaultNavHost="true"         app:layout_constraintBottom_toTopOf="@id/nav_view"         app:layout_constraintLeft_toLeftOf="parent"         app:layout_constraintRight_toRightOf="parent"         app:layout_constraintTop_toTopOf="parent"         app:navGraph="@navigation/mobile_navigation" /> 

navigation.xml

    <fragment         android:id="@+id/navigation_home"         android:name="com.pqtel.navtest.ui.home.HomeFragment"         android:label="@string/title_home"         tools:layout="@layout/fragment_home" />      <fragment         android:id="@+id/navigation_dashboard"         android:name="com.pqtel.navtest.ui.dashboard.DashboardFragment"         android:label="@string/title_dashboard"         tools:layout="@layout/fragment_dashboard" />      <fragment         android:id="@+id/navigation_notifications"         android:name="com.pqtel.navtest.ui.notifications.NotificationsFragment"         android:label="@string/title_notifications"         tools:layout="@layout/fragment_notifications" /> 

注意这里的fragment id 需要与menuitem id 一一对用，否则无法跳转