Google’s Android is a complete mobile operating system. While the technology is meant to challenge other mobile OSes-including Microsoft’s Windows Mobile and Apple’s iPhone-it also promises to be a key development platform.
For developers, that means using Java and Eclipse, and understanding the fundamental mobile architecture of Android. Here is an overview of the architecture.
Eclipse: The Preferred IDE
The preferred development environment for developing for Android is the open-source Eclipse IDE. While developers could use their favorite editor and command-line tools directly, development is certainly easier in Eclipse, since Google has given us a pretty nice plug-in to simplify development in Eclipse. This plug-in automatically creates a project for developers, including some starter files such as a class for the main application, which even includes some starting code.
Development, therefore, requires that Eclipse and the Android software development kit be installed, as well as the plug-in for Eclipse.
The Language Is Java
To develop for Android, programmers use the latest version of Java. Included with the Android SDK is a whole set of Java libraries found in such namespaces as android.app and android.os. These classes are all contained in a single jar file; looking at the jar file, I saw such namespaces as android.content, android.database, android.graphics, android.hardware, android.net, android.net.wifi (cool!), android.sax (as in
Additionally there’s a large set of Apache classes and World Wide Web Consortium classes. The Apache classes are primarily for HTTP communication, while the W3C classes are the DOM (Document Object Model) processing classes.
Remember, Android is a complete operating system, and as is obvious, through these Java classes, developers have access to a great deal of features that they can use in their programs.
I was curious about one aspect of the HTTP classes in particular. I looked through all the class names, and sure enough, this one was present: org.apache.http.HttpServerConnection. That’s for server-side processing. Does Android let developers run an actual HTTP server? HttpServerConnection is just an interface; on further inspection, I found this class: org.apache.http.impl.DefaultHttpServerConnection. Indeed, this class is an implementation of a server connection class. I didn’t have time for this particular article to explore this further, but I’m definitely going to do that soon. The idea of running server software on a mobile device is certainly intriguing.