android 里自定义属性

Currently the best documentation is the source. You can take a look at it here (attrs.xml).

You can define attributes in the top <resources> element or inside of a <declare-styleable>element. If I'm going to use an attr in more than one place I put it in the root element. Note, all attributes share the same global namespace（android）. That means that even if you create a new attribute inside of a<declare-styleable> element it can be used outside of it and you cannot create another attribute with the same name of a different type.

you can create another attribute with the same name of different type undering create a new namespace

eg. in android namespace you can :android:attr

     in self defined namespace  yournamespace:attr

An <attr> element has two xml attributes name and format. name lets you call it something and this is how you end up referring to it in code, e.g., R.attr.my_attribute. The format attribute can have different values depending on the 'type' of attribute you want.

• reference - if it references another resource id (e.g, "@color/my_color", "@layout/my_layout")
• color
• boolean
• dimension
• float
• integer
• string
• fraction
• enum - normally implicitly defined
• flag - normally implicitly defined