Android學習之“BottomNavigationView+ViewPager”實現底部導航與翻頁

一、效果圖

未使用app:labelVisibilityMode=“labeled”

二、實現步驟

1. 創建一個新的項目NavigationTest
2. 在app文件夾下的build.gradle中添加BottomNavigationView所需要的依賴庫

implementation 'com.android.support:design:28.0.0' //底部導航欄

3. 在res文件夾下面新建menu文件夾，並新建bottom_navigation_view.xml作爲導航欄的菜單文件，內含導航欄的選項圖標和選項文字。將圖標資源放入drawable文件夾下

<?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="首頁" />
    <item
        android:id="@+id/item_bottom_navigation_view_pt_job"
        android:icon="@drawable/pt_job"
        android:title="兼職" />
    <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添加選中與未選中的顏色

<!--底部導航欄顏色-->
<color name="bottom_navigation_view_checked">#1874CD</color>
<color name="bottom_navigation_view_unchecked">#7EC0EE</color>

5. 在drawable文件夾下新建bottom_navigation_view_selector.xml作爲底部導航欄樣式的配置文件。

<?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. 修改主函數的佈局文件activity_main.xml BottomNavigationView在底部，ViewPager填滿上方剩餘部分。

<?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"該屬性固定住圖標與文字，
		具體效果參見上方效果圖展示-->
    </android.support.design.widget.BottomNavigationView>
</LinearLayout>

7. 準備填充ViewPager的Fragment
A. 在values/strings.xml字符串資源文件中添加以下字符串

<string name="s_bottom_navigation_view_home">首頁</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">兼職</string>

B. Fragment的佈局文件（以首頁Fragment爲例）

<?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（以首頁Fragment爲例）

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 作爲ViewPager的適配器

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完成相應功能

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;
    //組件
    private BottomNavigationView mBottomNavigationView;
    private ViewPager mViewPager;
    //適配器
    private ViewPagerAdapterForNav mViewPagerAdapterForNav;

    private MenuItem menuItem;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //隱藏標題欄
        android.support.v7.app.ActionBar actionBar = getSupportActionBar();
        actionBar.hide();
        //實例化組件
        initElement();
        //初始化碎片集合
        initFragments();
        //導航欄與ViewPager聯動
        //給底部導航欄和ViewPager設置監聽器
        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) {

            }
        });
        //爲ViewPager設置適配器
        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());
    }
}