Android ViewPager2 + Fragment + BottomNavigationView 联动

迷南。 2023-09-23 17:36 111阅读 0赞

## Android ViewPager2 + Fragment + BottomNavigationView 联动 ##

> 本篇主要介绍一下 ViewPager2 + Fragment + BottomNavigationView , 上篇中把ViewPager2和Fragment 联动起来了, 本篇主要把 BottomNavigationView集成进去

![ef39b29dae8516b6a151820d418fd9d2.gif][]

#### 概述 ####

BottomNavigationView 是一个底部导航控件, `现在要实现的效果就是 滑动ViewPager2 中的Fragment 并且底部BottomNavigationView 菜单部分跟着联动` 同理反过来 点击BottomNavigationView 的时候 ViewPager2中的Fragment 也对应滑动, 下面来看看如何实现的吧

#### 实现思路 ####

1.Activity 布局文件中引入 ViewPager2 控件

2.`编写menu文件 提供给BottomNavigationView 用于展示`

3.Activity 布局文件中引入BottomNavigationView 控件

4.编写 Fragment 用于填充到ViewPager2中

5.`编写Adapter 实现 FragmentStateAdapter`

6.BottomNavigationView添加 setOnItemSelectedListener 联动ViewPager2

7.ViewPager2 添加 registerOnPageChangeCallback 联动 BottomNavigationView

#### 代码实现 ####

下面就来按照上面的思路一步步实现代码啦!

1.Activity 布局文件中引入 ViewPager2 控件

2.编写menu文件 提供给BottomNavigationView 用于展示

图标icon 自己配置吧

<?xml version="1.0" encoding="utf-8"?>
    <menu xmlns:android="http://schemas.android.com/apk/res/android">
    
        <item
            android:title="首页"
            android:id="@+id/home_item"
            android:icon="@drawable/ic_baseline_home_24"
            />
    
        <item
            android:title="类型"
            android:id="@+id/type_item"
            android:icon="@drawable/ic_baseline_merge_type_24"
            />
    
        <item
            android:title="添加"
            android:id="@+id/add_item"
            android:icon="@drawable/ic_baseline_add_24"
            />
    
        <item
            android:title="设置"
            android:id="@+id/setting_item"
            android:icon="@drawable/ic_baseline_settings_24"
            />
    </menu>
    复制代码

3.Activity 布局文件中引入BottomNavigationView 控件

package com.johnny.slzzing;
    
    import android.os.Bundle;
    
    import androidx.annotation.NonNull;
    import androidx.annotation.Nullable;
    import androidx.fragment.app.Fragment;
    
    import android.view.LayoutInflater;
    import android.view.View;
    import android.view.ViewGroup;
    import android.widget.TextView;
    
    import org.w3c.dom.Text;
    
    /**
     * A simple {@link Fragment} subclass.
     * Use the {@link Bottom2Fragment#newInstance} factory method to
     * create an instance of this fragment.
     */
    public class Bottom2Fragment extends Fragment {
    
        // TODO: Rename parameter arguments, choose names that match
        // the fragment initialization parameters, e.g. ARG_ITEM_NUMBER
        private static final String ARG_PARAM1 = "param1";
        private static final String ARG_PARAM2 = "param2";
    
        // TODO: Rename and change types of parameters
        private String mParam1;
        private String mParam2;
    
        public Bottom2Fragment() {
            // Required empty public constructor
        }
    
        /**
         * Use this factory method to create a new instance of
         * this fragment using the provided parameters.
         *
         * @param param1 Parameter 1.
         * @param param2 Parameter 2.
         * @return A new instance of fragment Bottom2Fragment.
         */
        // TODO: Rename and change types and number of parameters
        public static Bottom2Fragment newInstance(String param1, String param2) {
            Bottom2Fragment fragment = new Bottom2Fragment();
            Bundle args = new Bundle();
            args.putString(ARG_PARAM1, param1);
            args.putString(ARG_PARAM2, param2);
            fragment.setArguments(args);
            return fragment;
        }
    
        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            if (getArguments() != null) {
                mParam1 = getArguments().getString(ARG_PARAM1);
                mParam2 = getArguments().getString(ARG_PARAM2);
            }
        }
    
        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                                 Bundle savedInstanceState) {
            // Inflate the layout for this fragment
            return inflater.inflate(R.layout.fragment_bottom2, container, false);
        }
    
        @Override
        public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
            super.onViewCreated(view, savedInstanceState);
            TextView textView = view.findViewById(R.id.textview2);
            //把动态传入的参数设置到 textView上
            textView.setText(mParam1);
        }
    }
    复制代码

fragment\_bottom2.xml

<?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"
        tools:context=".ViewPager2BottomActivity">
    
    
        <androidx.viewpager2.widget.ViewPager2
            android:id="@+id/viewpager2bottom"
            android:layout_width="match_parent"
            android:layout_height="0dp"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent"
            app:layout_constraintBottom_toTopOf="@id/bootomnav2"
            />
    
        <com.google.android.material.bottomnavigation.BottomNavigationView
            android:id="@+id/bootomnav2"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            app:layout_constraintTop_toBottomOf="@id/viewpager2bottom"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:menu="@menu/bottom_item_menu"                                        
            app:labelVisibilityMode="labeled" 
            />
            
    </androidx.constraintlayout.widget.ConstraintLayout>
    复制代码

4.编写 Fragment 用于填充到ViewPager2中

<?xml version="1.0" encoding="utf-8"?>
    <androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        tools:context=".Bottom2Fragment">
    
        
        <TextView
            android:id="@+id/textview2"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:text="@string/hello_blank_fragment"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent"
            android:gravity="center"
            android:textSize="25sp"
            android:textStyle="bold"
            android:textColor="@color/black"
            />
    
    </androidx.constraintlayout.widget.ConstraintLayout>
    复制代码

5.`编写Adapter 实现 FragmentStateAdapter`

上篇已经说过了 直接继承 FragmentStateAdapter

class MyViewPager2BottomAdapter extends FragmentStateAdapter {
    
        List<Fragment> fragmentList;
        public MyViewPager2BottomAdapter(@NonNull FragmentActivity fragmentActivity, List<Fragment> list) {
            super(fragmentActivity);
            this.fragmentList = list;
        }
    
        @NonNull
        @Override
        public Fragment createFragment(int position) {
            return fragmentList.get(position);
        }
    
        @Override
        public int getItemCount() {
            return fragmentList.size();
        }
    }
    复制代码

6.BottomNavigationView添加 setOnItemSelectedListener 联动ViewPager2

`bottomNavigationView.setOnItemSelectedListener核心方法`

Acitivity 中实现如下代码:

7.ViewPager2 添加 registerOnPageChangeCallback 联动 BottomNavigationView

protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_view_pager2_bottom);
    
        viewPager2 = findViewById(R.id.viewpager2bottom);
        bottomNavigationView = findViewById(R.id.bootomnav2);
        MyViewPager2BottomAdapter myViewPager2BottomAdapter =
                new MyViewPager2BottomAdapter(this,initFragmentList());
        viewPager2.setAdapter(myViewPager2BottomAdapter);
    
        bottomNavigationView.setOnItemSelectedListener(new NavigationBarView.OnItemSelectedListener() {
            @Override
            public boolean onNavigationItemSelected(@NonNull MenuItem item) {
                int itemId = item.getItemId();
                switch (itemId){
                    case R.id.home_item:
                        viewPager2.setCurrentItem(0);
                        break;
                    case R.id.type_item:
                        viewPager2.setCurrentItem(1);
                        break;
                    case R.id.add_item:
                        viewPager2.setCurrentItem(2);
                        break;
                    case R.id.setting_item:
                        viewPager2.setCurrentItem(3);
                        break;
                }
                return true;
            }
        });
         //重点 实现滑动的时候 联动 bottomNavigationView的selectedItem
        viewPager2.registerOnPageChangeCallback(new ViewPager2.OnPageChangeCallback() {
            @Override
            public void onPageSelected(int position) {
                super.onPageSelected(position);
                switch (position){
                    case 0:
                        bottomNavigationView.setSelectedItemId(R.id.home_item);
                        break;
                    case 1:
                        bottomNavigationView.setSelectedItemId(R.id.type_item);
                        break;
                    case 2:
                        bottomNavigationView.setSelectedItemId(R.id.add_item);
                        break;
                    case 3:
                        bottomNavigationView.setSelectedItemId(R.id.setting_item);
                        break;
                }
            }
        });
    
    }
    复制代码

![93147c2973ab3a7d6d196e0ae0e5086b.png][]

总结

本篇主要介绍了 如何把ViewPager2 + Fragment + BottomNavigationView 集成起来并且实现ViewPager2和BottomNavigationView的双向联动

`ViewPager和ViewPager2 一些区别`:

*  ViewPager 的 Adapter 继承 FragmentStatePagerAdapter 而 ViewPager2 的Adapter 继承 FragmentStateAdapter
 *  ViewPager 滑动监听是 viewPager.addOnPageChangeListener方法 而ViewPager2 滑动监听是 registerOnPageChangeCallback 方法

[ef39b29dae8516b6a151820d418fd9d2.gif]: https://img-blog.csdnimg.cn/img_convert/ef39b29dae8516b6a151820d418fd9d2.gif
[93147c2973ab3a7d6d196e0ae0e5086b.png]: https://img-blog.csdnimg.cn/img_convert/93147c2973ab3a7d6d196e0ae0e5086b.png