安卓界面之Toolbar+tablayout+viewpager仿WhatsApp界面样式

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.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"
    android:orientation="vertical"
    tools:context=".MainActivity">
    <android.support.design.widget.CoordinatorLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <android.support.design.widget.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="100dp"
        android:gravity="center"
        android:elevation="0dp"
        app:elevation="0dp"
        android:id="@+id/appbar_id"
        >
        <android.support.v7.widget.Toolbar
            android:id="@+id/tb_id"
            android:layout_width="match_parent"
            android:layout_height="?android:attr/actionBarSize"
            android:background="?attr/colorPrimary"
            app:titleTextColor="@color/colorwhite"
            app:layout_scrollFlags="enterAlways"
            />
        <android.support.design.widget.TabLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            app:tabMaxWidth="0dp"
            app:tabGravity="fill"
            app:tabMode="fixed"
            android:id="@+id/tablayout_id"
            android:textAlignment="center"
            app:tabTextAppearance="@style/tabtextsize"
            app:tabSelectedTextColor="@color/tabindicatorcolor"
            app:tabTextColor="@color/tabtextcolor"
            app:tabIndicatorColor="@color/tabindicatorcolor"
            android:background="@color/colorPrimary"/>
    </android.support.design.widget.AppBarLayout>

        <!--设置fillViewport属性为true使viewpager可见-->
        <!--包含可滑动的布局内容(RecyclerView,NestedScrollView,不支持ListView，ScrollView，ViewPager),但是可以在NestedScrollView中使用
       必须要设置app:layout_behavior="@string/appbar_scrolling_view_behavior" (布局行为)
       属性来告知CoordinatorLayout该组件是带有滑动行为的组件,
       然后CoordinatorLayout在接受到滑动时会通知AppBarLayout中可滑动的Toolbar可以滑出屏幕-->
    <android.support.v4.widget.NestedScrollView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_behavior="@string/appbar_scrolling_view_behavior"
        android:fillViewport="true"
        >
        <android.support.v4.view.ViewPager
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:id="@+id/viewpager_id">
        </android.support.v4.view.ViewPager>
    </android.support.v4.widget.NestedScrollView>

</android.support.design.widget.CoordinatorLayout>
    </android.support.constraint.ConstraintLayout>