Navigation和BottomNavigationView结

1. 创建TaoBaoActivity

package com.example.mvvmdemo.BottonNavigationView.Activity

import android.os.Bundle
import androidx.appcompat.app.AppCompatActivity
import androidx.navigation.fragment.NavHostFragment
import androidx.navigation.ui.setupWithNavController
import com.example.mvvmdemo.R
import kotlinx.android.synthetic.main.activity_taobao_main.*

class TaoBaoActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_taobao_main)
        initView()
    }

    private fun initView() {
        //方法1：去fragment管理器里通过id找到NavHostFragment
        val navHostFragment: NavHostFragment = supportFragmentManager.findFragmentById(R.id.taoBao_navigation_host_fragment) as NavHostFragment
        bottomNavigationView.setupWithNavController(navHostFragment.navController)
    }
}

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

    <androidx.fragment.app.FragmentContainerView
        android:id="@+id/taoBao_navigation_host_fragment"
        android:name="androidx.navigation.fragment.NavHostFragment"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        app:defaultNavHost="true"
        app:layout_constraintBottom_toTopOf="@+id/bottomNavigationView"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:navGraph="@navigation/taobao_navigation_config" />

    <com.google.android.material.bottomnavigation.BottomNavigationView
        android:id="@+id/bottomNavigationView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:itemIconTint="@color/Orange"
        app:itemTextColor="@color/Orange"
        app:labelVisibilityMode="auto"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.0"
        app:layout_constraintStart_toStartOf="parent"
        app:menu="@menu/taobao_bottom_navigation_menu" />
</androidx.constraintlayout.widget.ConstraintLayout>

2. 创建Fragment

（1）创建BaseFragment，然后子Fragment继承即可

package com.example.mvvmdemo.base

import android.os.Bundle
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.fragment.app.Fragment

abstract class BaseFragment : Fragment() {
    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        val rootView: View = inflater.inflate(getLayoutResId(), container, false)
        //初始化View
        initView(rootView)
        return rootView
    }
    //可以选择性继承实现
    open fun initView(rootView: View) {

    }
    //子类传入View，必须实现
    abstract fun getLayoutResId(): Int
}

（2）创建其它Fragment

HomeFragment

package com.example.mvvmdemo.BottonNavigationView.Fragment

import com.example.mvvmdemo.R
import com.example.mvvmdemo.base.BaseFragment

class HomeFragment : BaseFragment() {
    override fun getLayoutResId(): Int {
        return R.layout.fragment_taobao_home
    }
}

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TextView
        android:id="@+id/textView3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="首页"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>

OnSellFragment

package com.example.mvvmdemo.BottonNavigationView.Fragment

import com.example.mvvmdemo.R
import com.example.mvvmdemo.base.BaseFragment

class OnSellFragment: BaseFragment() {
    override fun getLayoutResId(): Int {
        return R.layout.fragment_taobao_on_sell
    }
}

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TextView
        android:id="@+id/textView3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="特惠"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>

SelectedFragment

package com.example.mvvmdemo.BottonNavigationView.Fragment

import com.example.mvvmdemo.R
import com.example.mvvmdemo.base.BaseFragment

class SelectedFragment : BaseFragment() {
    override fun getLayoutResId(): Int {
        return R.layout.fragment_taobao_selected
    }
}

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TextView
        android:id="@+id/textView3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="精选"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>

SearchFragment

package com.example.mvvmdemo.BottonNavigationView.Fragment

import com.example.mvvmdemo.R
import com.example.mvvmdemo.base.BaseFragment

class SearchFragment : BaseFragment() {
    override fun getLayoutResId(): Int {
        return R.layout.fragment_taobao_search
    }
}

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TextView
        android:id="@+id/textView3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="搜索"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>

3. 创建Menu文件

   在res目录下创建menu子目录，创建taobao_bottom_navigation_menu.xml

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:android="http://schemas.android.com/apk/res/android">

    <item
        android:id="@+id/taoBao_home"
        android:icon="@mipmap/home_normal"
        android:title="首页" />
    <item
        android:id="@+id/taoBao_select"
        android:icon="@mipmap/select_normal"
        android:title="精选" />
    <item
        android:id="@+id/taoBao_onSell"
        android:icon="@mipmap/red_packet_normal"
        android:title="特惠" />
    <item
        android:id="@+id/taoBao_search"
        android:icon="@mipmap/search_normal"
        android:title="搜索" />
</menu>

4.创建Navigation文件

在res目录下创建navigation子目录，创建taobao_navigation_config.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"
    android:id="@+id/taobao_navigation_config"
    app:startDestination="@id/taoBao_home">

    <fragment
        android:id="@+id/taoBao_home"
        android:name="com.example.mvvmdemo.BottonNavigationView.Fragment.HomeFragment"
        android:label="HomeFragment" />
    <fragment
        android:id="@+id/taoBao_select"
        android:name="com.example.mvvmdemo.BottonNavigationView.Fragment.OnSellFragment"
        android:label="OnSellFragment" />
    <fragment
        android:id="@+id/taoBao_onSell"
        android:name="com.example.mvvmdemo.BottonNavigationView.Fragment.SearchFragment"
        android:label="SearchFragment" />
    <fragment
        android:id="@+id/taoBao_search"
        android:name="com.example.mvvmdemo.BottonNavigationView.Fragment.SelectedFragment"
        android:label="SelectedFragment" />
</navigation>

记得在TaoBaoActivity的布局文件的 androidx.fragment.app.FragmentContainerView 标签加入如下内容，才会和taobao_navigation_config,xml产生关联

<androidx.fragment.app.FragmentContainerView
    android:name="androidx.navigation.fragment.NavHostFragment"
    app:defaultNavHost="true"
    app:navGraph="@navigation/taobao_navigation_config" />

在TaoBaoActivity中添加如下代码对Fragment进行管理

private fun initView() {
    //去fragment管理器里通过id找到NavHostFragment
    val navHostFragment: NavHostFragment = supportFragmentManager.findFragmentById(R.id.taoBao_navigation_host_fragment) as NavHostFragment
    bottomNavigationView.setupWithNavController(navHostFragment.navController)
}