Android custom attributes on "normal" views?

After taking a look at theming for Fede's UberMusic I came across the file album_screen.xml. Below is the source of that file. Basically I noticed that his themes have the ability to use custom views that are a part of his application, and that they have this XML namespace at the top theme. I am missing the connection as to how he is able to apply his attributes to views that he does not control, and how Eclipse will compile the cod below without fail. I placed the URL http://schemas.uberdroidstudio.com/theme into my browser's address bar but nothing came up, and I cannot figure out where/ how Eclipse knows the attributes that the namespace supports. Thank you ahead of time for your help.

<?xml version="1.0" encoding="utf-8"?>
<merge
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:theme="http://schemas.uberdroidstudio.com/theme">
    <TextView  
        android:id="@id/artist"
        android:layout_width="wrap_content" 
        android:layout_height="wrap_content"
开发者_运维知识库        android:layout_weight="0.0"
        theme:textFilter="uppercase" /> <!-- This is the interesting line -->

I suspect that the theme:textFilter="uppercase" line isn't actually having an effect on the (apparently vanilla) TextView.

As for the URL of the namespace, it is interesting that you can't access it, since it does not appear to be a local styleable (Android would have you refer to a local styleable namespace as http://schemas.android.com/apk/res/your.package). +1 for novelty.

The solution is actually not as complicated as I originally thought. XML namespaces are arbitrary strings that just need to be unique. If your namespace does not start with http://schemas.android.com/apk/res then it is not validated and the APK package is not checked for declare-styleable or the like. Now a custom namespace if very simple to implement, as illustrated by this code snippet in GitHub. Finally, applying custom XML attributes to "normal" widgets can be accomplished by using the LayoutInflater.Factory and calling setFactory before you inflate your views. Throw it all together and you have a highly theme-able, XML driven application like Fede's UberMusic.