Java 如何在android中的布局中心制作选项卡

这些代码运行正常。但是我的查询是在ActionBar上显示的，我想在布局内部或ActionBar下面显示。请任何人帮帮我。请任何人帮助我显示内部布局选项卡

MainActivity.java类

public class MainActivity extends FragmentActivity {
  ViewPager Tab;
    TabPagerAdapter TabAdapter;
  ActionBar actionBar;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        TabAdapter = new TabPagerAdapter(getSupportFragmentManager());
        Tab = (ViewPager)findViewById(R.id.pager);
        Tab.setOnPageChangeListener(
                new ViewPager.SimpleOnPageChangeListener() {
                    @Override
                    public void onPageSelected(int position) {
                      actionBar = getActionBar();
                      actionBar.setSelectedNavigationItem(position);                    }
                });
        Tab.setAdapter(TabAdapter);
        actionBar = getActionBar();
        actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
        actionBar.setDisplayShowTitleEnabled(false);
        ActionBar.TabListener tabListener = new ActionBar.TabListener(){
      @Override
      public void onTabReselected(android.app.ActionBar.Tab tab,
          FragmentTransaction ft) {
      }
      @Override
       public void onTabSelected(ActionBar.Tab tab, FragmentTransaction ft) {
              Tab.setCurrentItem(tab.getPosition());
          }
      @Override
      public void onTabUnselected(android.app.ActionBar.Tab tab,
          FragmentTransaction ft) {
      }};
      //Add New Tab
      actionBar.addTab(actionBar.newTab().setText("Android").setTabListener(tabListener));
      actionBar.addTab(actionBar.newTab().setText("iOS").setTabListener(tabListener));
      actionBar.addTab(actionBar.newTab().setText("Windows").setTabListener(tabListener));
    }
}

TabPagerAdapter.java类

public class TabPagerAdapter extends FragmentStatePagerAdapter {
        public TabPagerAdapter(FragmentManager fm) {
        super(fm);
      }
      @Override
      public Fragment getItem(int i) {
        switch (i) {
            case 0:
                return new Android();
            case 1:
                return new Ios();
            case 2:
                return new Windows();
            }
        return null;
      }
      @Override
      public int getCount() {
        return 3; 
      }
    }

Ios.java、Android.java和Windows.java类是类似的代码：

public class Ios extends Fragment {
   @Override
      public View onCreateView(LayoutInflater inflater, ViewGroup container,
              Bundle savedInstanceState) {
          View ios = inflater.inflate(R.layout.ios_frag, container, false);
          ((TextView)ios.findViewById(R.id.textView)).setText("iOS");
          return ios;
    }
   }

<?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:gravity="center"
    android:orientation="vertical" >
    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="50sp"/>
</LinearLayout>

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.view.ViewPager
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/pager"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

android_frag.xml、ios_frag和windows_frag.xml是类似的代码：

public class Ios extends Fragment {
   @Override
      public View onCreateView(LayoutInflater inflater, ViewGroup container,
              Bundle savedInstanceState) {
          View ios = inflater.inflate(R.layout.ios_frag, container, false);
          ((TextView)ios.findViewById(R.id.textView)).setText("iOS");
          return ios;
    }
   }

<?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:gravity="center"
    android:orientation="vertical" >
    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="50sp"/>
</LinearLayout>

---

通过自定义我的应用程序主题

在AndroidManifest.xml中，添加android:theme属性：

<application
        android:label="@string/app_name"
        android:icon="@drawable/ic_launcher"
        android:theme="@style/CustomActionBarTheme">
  ...

...

在themes.xml中添加：

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <!-- the theme applied to the application or activity -->
    <style name="CustomActionBarTheme"
           parent="@android:style/Theme.Holo.Light.DarkActionBar">
        <item name="android:actionBarTabBarStyle">@style/MyActionBarTabBar</item>
    </style>

    <style name="MyActionBarTabBar">
        <item name="android:gravity">center</item>
    </style>
</resources>

@style/MyActionBartabar
居中

选项卡现在应该居中对齐