Android学习之“BottomNavigationView+ViewPager”实现底部导航与翻页

一、效果图

未使用app:labelVisibilityMode=“labeled”

二、实现步骤

1. 创建一个新的项目NavigationTest
2. 在app文件夹下的build.gradle中添加BottomNavigationView所需要的依赖库

implementation 'com.android.support:design:28.0.0' //底部导航栏

3. 在res文件夹下面新建menu文件夹，并新建bottom_navigation_view.xml作为导航栏的菜单文件，内含导航栏的选项图标和选项文字。将图标资源放入drawable文件夹下

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:id="@+id/item_bottom_navigation_view_home" android:icon="@drawable/home" android:title="首页" />
    <item android:id="@+id/item_bottom_navigation_view_pt_job" android:icon="@drawable/pt_job" android:title="兼职" />
    <item android:id="@+id/item_bottom_navigation_view_message" android:icon="@drawable/message" android:title="消息" />
    <item android:id="@+id/item_bottom_navigation_view_personal" android:icon="@drawable/personal" android:title="我的" />
</menu>

4. 在values/colors.xml添加选中与未选中的颜色

<!--底部导航栏颜色-->
<color name="bottom_navigation_view_checked">#1874CD</color>
<color name="bottom_navigation_view_unchecked">#7EC0EE</color>

5. 在drawable文件夹下新建bottom_navigation_view_selector.xml作为底部导航栏样式的配置文件。

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:color="@color/bottom_navigation_view_checked" android:state_checked="true" />
    <item android:color="@color/bottom_navigation_view_unchecked" android:state_checked="false" />
</selector>

6. 修改主函数的布局文件activity_main.xml BottomNavigationView在底部，ViewPager填满上方剩余部分。

<?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:orientation="vertical" android:layout_width="match_parent" android:layout_height="match_parent" tools:context=".MainActivity">

    <android.support.v4.view.ViewPager android:id="@+id/activity_main_view_pager" android:layout_width="match_parent" android:layout_height="0dp" android:layout_weight="1">

    </android.support.v4.view.ViewPager>
    <android.support.design.widget.BottomNavigationView android:id="@+id/activity_main_bottom_navigation_view" android:layout_width="match_parent" android:layout_height="52dp" app:itemBackground="@null" app:itemIconTint="@drawable/bottom_navigation_view_selector" app:itemTextColor="@drawable/bottom_navigation_view_selector" app:labelVisibilityMode="labeled" app:menu="@menu/bottom_navigation_view">
	<!--app:labelVisibilityMode="labeled"该属性固定住图标与文字， 具体效果参见上方效果图展示-->
    </android.support.design.widget.BottomNavigationView>
</LinearLayout>

7. 准备填充ViewPager的Fragment
A. 在values/strings.xml字符串资源文件中添加以下字符串

<string name="s_bottom_navigation_view_home">首页</string>
<string name="s_bottom_navigation_view_message">消息</string>
<string name="s_bottom_navigation_view_personal">我的</string>
<string name="s_bottom_navigation_view_pt_job">兼职</string>

B. Fragment的布局文件（以首页Fragment为例）

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent">
    <TextView android:layout_width="match_parent" android:layout_height="match_parent" android:gravity="center" android:text="@string/s_bottom_navigation_view_home"/>
</android.support.constraint.ConstraintLayout>

C. Fragment的Java文件（以首页Fragment为例）

import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

public class HomeFragment extends Fragment {

    public static HomeFragment newInstance(){
        HomeFragment indexFragment = new HomeFragment();
        return indexFragment;
    }

    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_home,container,false);
        return view;
    }
}

8. 新建ViewPagerAdapterForNav.java 作为ViewPager的适配器

import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentStatePagerAdapter;

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

public class ViewPagerAdapterForNav extends FragmentStatePagerAdapter {
    //碎片集合
    private List<Fragment> mFragments = new ArrayList<>();

    public ViewPagerAdapterForNav(FragmentManager fm) {
        super(fm);
    }

    @Override
    public int getCount() {
        if (mFragments == null){
            return 0;
        }else{
            return mFragments.size();
        }
    }

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

    public void setFragments(List<Fragment> fragments) {
        this.mFragments = fragments;
        notifyDataSetChanged();
    }

}

9. 修改MainActivity.java完成相应功能

import android.support.design.widget.BottomNavigationView;
import android.support.v4.app.Fragment;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.MenuItem;

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

public class MainActivity extends AppCompatActivity {
    //碎片集合
    List<Fragment> mFragments;
    //组件
    private BottomNavigationView mBottomNavigationView;
    private ViewPager mViewPager;
    //适配器
    private ViewPagerAdapterForNav mViewPagerAdapterForNav;

    private MenuItem menuItem;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //隐藏标题栏
        android.support.v7.app.ActionBar actionBar = getSupportActionBar();
        actionBar.hide();
        //实例化组件
        initElement();
        //初始化碎片集合
        initFragments();
        //导航栏与ViewPager联动
        //给底部导航栏和ViewPager设置监听器
        mBottomNavigationView.setOnNavigationItemSelectedListener(mOnNavigationItemSelectedListener);
        mViewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
            @Override
            public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

            }

            @Override
            public void onPageSelected(int position) {
                if (menuItem != null) {
                    menuItem.setChecked(false);
                } else {
                    mBottomNavigationView.getMenu().getItem(0).setChecked(false);
                }
                menuItem = mBottomNavigationView.getMenu().getItem(position);
                menuItem.setChecked(true);
            }

            @Override
            public void onPageScrollStateChanged(int state) {

            }
        });
        //为ViewPager设置适配器
        mViewPagerAdapterForNav = new ViewPagerAdapterForNav(getSupportFragmentManager());
        mViewPager.setAdapter(mViewPagerAdapterForNav);
        mViewPagerAdapterForNav.setFragments(mFragments);

    }

    private BottomNavigationView.OnNavigationItemSelectedListener mOnNavigationItemSelectedListener = new BottomNavigationView.OnNavigationItemSelectedListener() {

        @Override
        public boolean onNavigationItemSelected(MenuItem item) {
            menuItem = item;
            switch (item.getItemId()) {
                case R.id.item_bottom_navigation_view_home:
                    mViewPager.setCurrentItem(0);
                    return true;
                case R.id.item_bottom_navigation_view_pt_job:
                    mViewPager.setCurrentItem(1);
                    return true;
                case R.id.item_bottom_navigation_view_message:
                    mViewPager.setCurrentItem(2);
                    return true;
                case R.id.item_bottom_navigation_view_personal:
                    mViewPager.setCurrentItem(3);
                    return true;
            }
            return false;
        }
    };

    private void initElement(){
        mBottomNavigationView = (BottomNavigationView)findViewById(R.id.activity_main_bottom_navigation_view);
        mViewPager = (ViewPager)findViewById(R.id.activity_main_view_pager);
    }

    private void initFragments(){
        mFragments = new ArrayList<>();
        mFragments.add(HomeFragment.newInstance());
        mFragments.add(Pt_jobFragment.newInstance());
        mFragments.add(MessageFragment.newInstance());
        mFragments.add(PersonalFragment.newInstance());
    }
}