Application Security for the Android Platform

Chapter 4. Component Security and Permissions

The Types of Android Components

Android apps are composed of one of more components, of which there are multiple types. Each component can be secured in a slightly different way, so before we start talking about how to do so, a quick review of the types of components should be helpful.

The component that most Android developers learn about first is the Activity. An Activity is analogous to a single screen displayed on the device to a user that is composed of what the user actually sees. When building an app, you create classes that derive from the Activity base class and typically contain one or more Views, which are objects that users can interact with in some way, such as reading text displayed within the View, clicking a button, and so on. In proper application development terminology, the set of Activities is your application’s presentation layer.

A Service is an Android component that is designed for background processing. These components can run when your app is not visible (that is, none of its Activities are being displayed to the user and are not active). Services typically either carry out some computations or update the data sources for your app. For example, if you were to build an email client app, a Service would run in the background to open up connections to the configured mail servers every so often, check for new mail, download it, and store new messages in the local database. Services can also be used to update Activities ...