To have a centered title in ABS (if you want to have this in the default ActionBar, just remove the "support" in the method names), you could just do this:
In your Activity, in your onCreate() method:
getSupportActionBar().setDisplayOptions(ActionBar.DISPLAY_SHOW_CUSTOM);
getSupportActionBar().setCustomView(R.layout.abs_layout);
abs_layout:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:orientation="vertical">
<android.support.v7.widget.AppCompatTextView
android:id="@+id/tvTitle"
style="@style/TextAppearance.AppCompat.Widget.ActionBar.Title"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:gravity="center"
android:textColor="#FFFFFF" />
</LinearLayout>
Now you should have an Actionbar with just a title. If you want to set a custom background, set it in the Layout above (but then don't forget to set android:layout_height="match_parent").
or with:
getSupportActionBar().setBackgroundDrawable(getResources().getDrawable(R.drawable.yourimage));