Android中TabLayout+ViewPager 简单实现app底部Tab导航栏

2019-12-12 03:37:09

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前言

在谷歌发布Android Design Support Library之前，app底部tab布局的实现方法就有很多种，其中有RadioGroup+FrameLayout、TabHost+Fragment、FragmentPagerAdapter+ViewPager等方法，虽然这些方法虽然能达到同样的效果，但我个人总觉得有些繁琐。然而，Google在2015的IO大会上，给开发者们带来了全新的Android Design Support Library，里面包含了许多新控件，这些新控件有许多是把以前的一些第三方开源库官方化，实现起来更为简便，简直是开发者的福音。其中的TabLayout控件让我想到了app底部的tab布局，而且TabLayout用法更加简单，为何不试试用TabLayout实现简单的实现呢？好了，话不多说，先看看效果：

是不是和以前的方法实现的效果一样呢？下面我们来看看怎么简单实现。

过程

因为TabLayout和ViewPager分别是属于design和v4包下的，所以我们先在app的build.gradle中添加：

compile 'com.android.support:design:23.1.1'compile 'com.android.support:support-v4:23.1.1'

然后在主布局文件activity_main.xml中添加布局控件：

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" xmlns:app="http://schemas.android.com/apk/res-auto" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" tools:context=".MainActivity"> <android.support.v4.view.ViewPager  android:id="@+id/viewPager"  android:layout_width="match_parent"  android:layout_height="0dp"  android:layout_weight="1"  android:scrollbars="none"> </android.support.v4.view.ViewPager> <android.support.design.widget.TabLayout  android:id="@+id/tabLayout"  android:layout_width="match_parent"  android:layout_height="50dp"  app:tabGravity="fill"  app:tabIndicatorHeight="0dp"  app:tabMode="fixed"  app:tabSelectedTextColor="#FF4081"  app:tabTextColor="#000"> </android.support.design.widget.TabLayout></LinearLayout>

就仅一个ViewPager和TabLayout就可以实现，是不是比以前的方法繁琐的布局简便很多？上面TabLayout中app:tabIndicatorHeight="0dp"是为了不显示tab底部的横线，app:tabMode="fixed"是让底部tab布局不可滑动。

接下来就和往常一样在MainActivity.java中初始化布局，设置适配器：

 private void initViews() {  mTablayout= (TabLayout) findViewById(R.id.tabLayout);  mViewPager= (ViewPager) findViewById(R.id.viewPager);  mViewPager.setAdapter(new FragmentPagerAdapter(getSupportFragmentManager()) {   private String[] mTitles = new String[]{"唐僧", "大师兄", "二师兄","沙师弟"};   @Override   public Fragment getItem(int position) {    if (position == 1) {     return new TwoFragment();    } else if (position == 2) {     return new ThreeFragment();    }else if (position==3){     return new FourFragment();    }    return new OneFragment();   }   @Override   public int getCount() {    return mTitles.length;   }   @Override   public CharSequence getPageTitle(int position) {    return mTitles[position];   }  });  mTablayout.setupWithViewPager(mViewPager);  one = mTablayout.getTabAt(0);  two = mTablayout.getTabAt(1);  three = mTablayout.getTabAt(2);  four = mTablayout.getTabAt(3);  one.setIcon(getResources().getDrawable(R.drawable.ic_favorite_black_18dp));  two.setIcon(getResources().getDrawable(R.mipmap.ic_launcher));  three.setIcon(getResources().getDrawable(R.mipmap.ic_launcher));  four.setIcon(getResources().getDrawable(R.mipmap.ic_launcher)); }

上面要注意的地方是别忘了在FragmentPagerAdapter中手动添加：

   @Override   public CharSequence getPageTitle(int position) {    return mTitles[position];   }

不然不显示底部的文字。

mTablayout.setupWithViewPager(mViewPager);将TabLayout和ViewPager关联起来。

one = mTablayout.getTabAt(0);获取底部单个tab，用来添加初始化图片，注意下标都是从0开始的。

初始化监听事件

 private void initEvents() {  mTablayout.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {   @Override   public void onTabSelected(TabLayout.Tab tab) {    if (tab == mTablayout.getTabAt(0)) {     one.setIcon(getResources().getDrawable(R.drawable.ic_favorite_black_18dp));     mViewPager.setCurrentItem(0);    } else if (tab == mTablayout.getTabAt(1)) {     two.setIcon(getResources().getDrawable(R.drawable.ic_favorite_black_18dp));     mViewPager.setCurrentItem(1);    } else if (tab == mTablayout.getTabAt(2)) {     three.setIcon(getResources().getDrawable(R.drawable.ic_favorite_black_18dp));     mViewPager.setCurrentItem(2);    }else if (tab == mTablayout.getTabAt(3)){     four.setIcon(getResources().getDrawable(R.drawable.ic_favorite_black_18dp));     mViewPager.setCurrentItem(3);    }   }   @Override   public void onTabUnselected(TabLayout.Tab tab) {    if (tab == mTablayout.getTabAt(0)) {     one.setIcon(getResources().getDrawable(R.mipmap.ic_launcher));    } else if (tab == mTablayout.getTabAt(1)) {     two.setIcon(getResources().getDrawable(R.mipmap.ic_launcher));    } else if (tab == mTablayout.getTabAt(2)) {     three.setIcon(getResources().getDrawable(R.mipmap.ic_launcher));    }else if (tab == mTablayout.getTabAt(3)){     four.setIcon(getResources().getDrawable(R.mipmap.ic_launcher));    }   }   @Override   public void onTabReselected(TabLayout.Tab tab) {   }  }); }

在onTabSelected中设置选中tab时切换的图片，onTabUnselected中设置没有被选中时的图片。别忘了mViewPager.setCurrentItem(0);这句，这是用来点击tab时切换ViewPager，如果不加这一句的话滑动ViewPager底部tab可以切换，但是点击tab而ViewPager不会切换。

Fragment中的简单布局

fragment_one.xml

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical"> <TextView  android:layout_width="wrap_content"  android:layout_height="wrap_content"  android:text="唐僧"  android:layout_marginTop="100dp"  android:layout_gravity="center"  android:textSize="30sp"/></LinearLayout>

OneFragment.java

public class OneFragment extends Fragment{ @Nullable @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {  return inflater.inflate(R.layout.fragment_one,container,false); } @Override public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {  super.onViewCreated(view, savedInstanceState); }}

MainActivity.java完整代码：

public class MainActivity extends AppCompatActivity { private TabLayout mTablayout; private ViewPager mViewPager; private TabLayout.Tab one; private TabLayout.Tab two; private TabLayout.Tab three; private TabLayout.Tab four; @Override protected void onCreate(Bundle savedInstanceState) {  super.onCreate(savedInstanceState);  setContentView(R.layout.activity_main);  initViews();  initEvents(); } private void initEvents() {  mTablayout.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {   @Override   public void onTabSelected(TabLayout.Tab tab) {    if (tab == mTablayout.getTabAt(0)) {     one.setIcon(getResources().getDrawable(R.drawable.ic_favorite_black_18dp));     mViewPager.setCurrentItem(0);    } else if (tab == mTablayout.getTabAt(1)) {     two.setIcon(getResources().getDrawable(R.drawable.ic_favorite_black_18dp));     mViewPager.setCurrentItem(1);    } else if (tab == mTablayout.getTabAt(2)) {     three.setIcon(getResources().getDrawable(R.drawable.ic_favorite_black_18dp));     mViewPager.setCurrentItem(2);    }else if (tab == mTablayout.getTabAt(3)){     four.setIcon(getResources().getDrawable(R.drawable.ic_favorite_black_18dp));     mViewPager.setCurrentItem(3);    }   }   @Override   public void onTabUnselected(TabLayout.Tab tab) {    if (tab == mTablayout.getTabAt(0)) {     one.setIcon(getResources().getDrawable(R.mipmap.ic_launcher));    } else if (tab == mTablayout.getTabAt(1)) {     two.setIcon(getResources().getDrawable(R.mipmap.ic_launcher));    } else if (tab == mTablayout.getTabAt(2)) {     three.setIcon(getResources().getDrawable(R.mipmap.ic_launcher));    }else if (tab == mTablayout.getTabAt(3)){     four.setIcon(getResources().getDrawable(R.mipmap.ic_launcher));    }   }   @Override   public void onTabReselected(TabLayout.Tab tab) {   }  }); } private void initViews() {  mTablayout= (TabLayout) findViewById(R.id.tabLayout);  mViewPager= (ViewPager) findViewById(R.id.viewPager);  mViewPager.setAdapter(new FragmentPagerAdapter(getSupportFragmentManager()) {   private String[] mTitles = new String[]{"唐僧", "大师兄", "二师兄","沙师弟"};   @Override   public Fragment getItem(int position) {    if (position == 1) {     return new TwoFragment();    } else if (position == 2) {     return new ThreeFragment();    }else if (position==3){     return new FourFragment();    }    return new OneFragment();   }   @Override   public int getCount() {    return mTitles.length;   }   @Override   public CharSequence getPageTitle(int position) {    return mTitles[position];   }  });  mTablayout.setupWithViewPager(mViewPager);  one = mTablayout.getTabAt(0);  two = mTablayout.getTabAt(1);  three = mTablayout.getTabAt(2);  four = mTablayout.getTabAt(3);  one.setIcon(getResources().getDrawable(R.drawable.ic_favorite_black_18dp));  two.setIcon(getResources().getDrawable(R.mipmap.ic_launcher));  three.setIcon(getResources().getDrawable(R.mipmap.ic_launcher));  four.setIcon(getResources().getDrawable(R.mipmap.ic_launcher)); }}

结束语

以上就是简单用TabLayout+ViewPager实现app底部Tab布局的整个过程，希望对大家的学习有所帮助，也希望大家多多支持武林网。

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