开发过程中经常会遇到Tab左右或中间的圆角不一样，如下图所示：

根据上图发现两个Tab圆角不同，且不对称，无法通过设置tabBackground属性来实现不同的圆角，解决方案是采用自定义TabView的方法。具体实现方案如下：
TabLayout属性设置：

<android.support.design.widget.TabLayout
        android:id="@+id/tb_layout"
        android:layout_width="wrap_content"
        android:layout_height="45dp"
        android:layout_marginTop="15dp"
        android:layout_marginLeft="15dp"
        android:layout_marginRight="15dp"
        android:padding="0dp"
        app:tabIndicatorHeight="0dp"
        app:tabPaddingBottom="0dp"
        app:tabPaddingEnd="0dp"
        app:tabPaddingStart="0dp"
        app:tabPaddingTop="0dp"
        app:tabSelectedTextColor="@color/white"
        app:tabTextAppearance="@style/text_14_33_df"/>

tabPadding和padding全部设置为0，由自定义TabView来设置相应的padding，tabIndicatorHeight设置为0，tabSelectedTextColor设置选中Tab文字颜色，tabTextAppearance设置Tab未选中文字颜色。
左边Tab选中背景bg_tab_left_select.xml：

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
    <solid
        android:color="@color/tv_color_blue"/>
    <corners
        android:topLeftRadius="5dp"/>
</shape>

左边Tab未选中背景bg_tab_left_unselect.xml：

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
    <solid
        android:color="@color/white"/>
    <corners
        android:topLeftRadius="5dp"/>
</shape>

右边Tab选中背景bg_tab_right_select.xml：

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
    <solid
        android:color="@color/tv_color_blue"/>

    <corners
        android:topRightRadius="5dp"/>
</shape>

右边Tab未选中背景bg_tab_right_unselect.xml：

<shape xmlns:android="http://schemas.android.com/apk/res/android">
    <solid
        android:color="@color/white"/>
    <corners
        android:topRightRadius="5dp"/>
</shape>

左边Tab背景选择器tab_left_selector.xml：

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:drawable="@drawable/bg_tab_left_unselect" android:state_selected="false"/>
    <item android:drawable="@drawable/bg_tab_left_select" android:state_selected="true"/>
</selector>

右边Tab背景选择器tab_right_selector.xml：

<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:drawable="@drawable/bg_tab_right_unselect" android:state_selected="false"/>
    <item android:drawable="@drawable/bg_tab_right_select" android:state_selected="true"/>
</selector>

左边TabView自定义布局文件：

<?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="45dp"
              android:background="@drawable/tab_left_selector"
              android:gravity="center"
              android:orientation="vertical">

    <TextView
        android:id="@+id/tab_text_left"
        android:layout_width="wrap_content"
        android:layout_height="45dp"
        android:gravity="center"
        android:textSize="@dimen/text_size_14"
        android:paddingLeft="15dp"
        android:paddingRight="15dp"
        android:textColor="@color/tv_color_33"/>
</LinearLayout>

右边TabView自定义布局文件：

<?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="45dp"
              android:background="@drawable/tab_right_selector"
              android:gravity="center"
              android:orientation="vertical">

    <TextView
        android:id="@+id/tab_text_right"
        android:layout_width="wrap_content"
        android:layout_height="45dp"
        android:gravity="center"
        android:textSize="@dimen/text_size_14"
        android:paddingLeft="15dp"
        android:paddingRight="15dp"
        android:textColor="@color/tv_color_33"/>

</LinearLayout>

注意：
自定义View的高度要保持与TabLayout高度一致，负责背景填充有问题。
最后代码实现：

viewPager.setOffscreenPageLimit(fragments.size());
        tabLayout.setTabMode(TabLayout.MODE_SCROLLABLE);
        tabLayout.setupWithViewPager(viewPager);

if (tabLayout != null) {
            TabLayout.Tab tab1 = tabLayout.getTabAt(0);
            if (tab1 != null) {
                tab1.setCustomView(getTabView0(getActivity()));
            }
            TabLayout.Tab tab2 = tabLayout.getTabAt(1);
            if (tab2 != null) {
                tab2.setCustomView(getTabView1(getActivity()));
            }
        }


public View getTabView0(Context context) {
        LayoutInflater mInflater = LayoutInflater.from(context);
        View view = mInflater.inflate(R.layout.item_tab_left, null);
        TextView tv = (TextView) view.findViewById(R.id.tab_text_left);
        tv.setText(titles[0]);
        return view;
    }

    public View getTabView1(Context context) {
        LayoutInflater mInflater = LayoutInflater.from(context);
        View view = mInflater.inflate(R.layout.item_tab_right, null);
        TextView tv = (TextView) view.findViewById(R.id.tab_text_right);
        tv.setText(titles[1]);
        return view;
    }