How to make gradient background in android

Question

As in the example below, I want to make a gradient background with a solid colour in the bottom and a gradient in the top.

I can't because the centerColor spreads out to cover the bottom and top.

How can I create a background that looks like the first picture? How can I create a small, uniform centre colour?

The XML code for the background button is shown above.

<shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="rectangle" >
    <gradient 
        android:startColor="#6586F0"
        android:centerColor="#D6D6D6"
        android:endColor="#4B6CD6"
        android:angle="90"/>
    <corners 
        android:radius="0dp"/>


</shape>