BottomNavigationView之底部导航栏的实现

1、导入依赖包

    implementation 'com.android.support:design:28.0.0'

2、编写布局

activity_main.xml代码：
此处特别注意设置app:labelVisibilityMode="labeled"，
不然底部标题不会显示

image.png

设置后效果图：

image.png

<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.DrawerLayout 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/drawer_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true"
    tools:openDrawer="start">

    <android.support.design.widget.CoordinatorLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <include
            android:id="@+id/include_toolbar"
            layout="@layout/toolbar" />

        <!--<include layout="@layout/container" />-->

        <android.support.v4.view.ViewPager
            android:id="@+id/vp_main"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            app:layout_constraintBottom_toTopOf="@+id/bottom_navigation"
            app:layout_constraintLeft_toLeftOf="parent"
            app:layout_constraintRight_toRightOf="parent"
            app:layout_constraintTop_toTopOf="parent">

        </android.support.v4.view.ViewPager>

        <android.support.design.widget.BottomNavigationView
            android:id="@+id/bottom_navigation"
            style="@style/Widget.Design.BottomNavigationView"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_alignParentBottom="true"
            android:layout_gravity="bottom"
            android:background="@color/c_F5F5F5"
            app:elevation="16dp"
            app:itemTextColor="@color/selector_tab_color"
            app:labelVisibilityMode="labeled"
            app:layout_behavior="com.hzy.wanandroid.widget.behavior.BottomNavigationBehavior"
            app:menu="@menu/bottom_navigation_main" />

    </android.support.design.widget.CoordinatorLayout>

    <android.support.design.widget.NavigationView
        android:id="@+id/nav_view"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="start"
        android:fitsSystemWindows="true"
        app:headerLayout="@layout/nav_header_main"
        app:menu="@menu/activity_main_drawer" />

</android.support.v4.widget.DrawerLayout>

bottom_navigation_main.xml 代码：

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">
    <item
        android:id="@+id/action_home"
        android:enabled="true"
        android:icon="@drawable/bt_tab_one_selector"
        android:title="首页"
        app:showAsAction="ifRoom" />
    <item
        android:id="@+id/action_project"
        android:enabled="true"
        android:icon="@drawable/bt_tab_two_selector"
        android:title="项目"
        app:showAsAction="ifRoom" />
    <item
        android:id="@+id/action_system"
        android:enabled="true"
        android:icon="@drawable/bt_tab_three_selector"
        android:title="体系"
        app:showAsAction="ifRoom" />
    <item
        android:id="@+id/action_navi"
        android:enabled="true"
        android:icon="@drawable/bt_tab_four_selector"
        android:title="导航"
        app:showAsAction="ifRoom" />

    <item
        android:id="@+id/action_pub"
        android:enabled="true"
        android:icon="@drawable/bt_tab_five_selector"
        android:title="公众号"
        app:showAsAction="ifRoom" />
</menu>

bt_tab_one_selector.xml 代码：

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <!--选中时的图片背景-->
    <item android:state_selected="true" android:drawable="@drawable/hy_b" />
    <item android:state_checked="true" android:drawable="@drawable/hy_b" />
    <item android:drawable="@drawable/hy_a"></item>
</selector>

3、代码设置

①、除去自带效果,此处设置主要用于selector文件内不同图片的颜色改变，不按照系统给的颜色去变化。

mBtNavi.setItemIconTintList(null);//除去自带效果

②、BottomNavigationView设置ViewPagerAdapter

        mViewPagerAdapter = new ViewPagerAdapter(getSupportFragmentManager(), fragments);
        mVpMain.setAdapter(mViewPagerAdapter);
        mVpMain.setOffscreenPageLimit(4);

ViewPagerAdapter 代码：

package com.hzy.wanandroid.adapter;

import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.view.PagerAdapter;

import java.util.ArrayList;
import java.util.List;

public class ViewPagerAdapter extends FragmentPagerAdapter {

    private List<Fragment> mFragments;
    private List<String> listTitle = new ArrayList<>();

    public ViewPagerAdapter(FragmentManager fm, List<Fragment> mFragments) {
        super(fm);
        this.mFragments = mFragments;
    }

    public ViewPagerAdapter(FragmentManager fm, List<Fragment> mFragments, List<String> listTitle) {
        super(fm);
        this.mFragments = mFragments;
        this.listTitle = listTitle;
    }

    @Override
    public Fragment getItem(int position) {
        return mFragments.get(position);
    }

    @Override
    public int getCount() {
        return mFragments.size();
    }

    @Override
    public CharSequence getPageTitle(int position) {
        return listTitle.get(position);
    }

    @Override
    public int getItemPosition(Object object) {
        return PagerAdapter.POSITION_NONE;
    }

    public void recreateItems(List<Fragment> fragmentList, List<String> titleList) {
        this.mFragments = fragmentList;
        this.listTitle = titleList;
        notifyDataSetChanged();
    }
}

③、设置页面滑动和底部点击关联

private void initListener() {
        mBtNavi.setOnNavigationItemSelectedListener(item -> {
            switch (item.getItemId()) {
                case R.id.action_home:
                    NaviTab(0);
                    break;
                case R.id.action_project:
                    NaviTab(1);
                    break;
                case R.id.action_system:
                    NaviTab(2);
                    break;
                case R.id.action_navi:
                    NaviTab(3);
                    break;
                case R.id.action_pub:
                    NaviTab(4);
                    break;
            }
            return true;
        });

        mVpMain.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
            @Override
            public void onPageScrolled(int position, float positionOffset,
                                       int positionOffsetPixels) {

            }

            @Override
            public void onPageSelected(int position) {
                mBtNavi.getMenu().getItem(position).setChecked(true);
                toolbar.setTitle(mTitleStrs[position]);
                //写滑动页面后做的事，使每一个fragmen与一个page相对应
            }

            @Override
            public void onPageScrollStateChanged(int i) {

            }
        });
    }

    /**
     * 点击Navigation切换Tab
     *
     * @param position
     */
    private void NaviTab(int position) {
        mVpMain.setCurrentItem(position);
        toolbar.setTitle(mTitleStrs[position]);
    }

总结，整体要注意：
在activity_main.xml代码内：

app:labelVisibilityMode="labeled"

和MainActivity内

mBtNavi.setItemIconTintList(null);//除去自带效果，在xml内设置无效。

参考文章：
https://blog.csdn.net/xyx2999/article/details/82839197
https://blog.csdn.net/qq_24577109/article/details/83505354