Professional Android, 4th Edition

7Using Internet Resources

WHAT'S IN THIS CHAPTER?

• Connecting to Internet resources
• Using Asynchronous Tasks to download and process Internet resources on background threads
• Using View Models and Live Data to store and observe data
• Parsing XML resources
• Parsing JSON feeds
• Using the Download Manager to download files
• Minimizing battery drain when transferring data

WROX.COM CODE DOWNLOADS FOR THIS CHAPTER

The code downloads for this chapter are found at www.wrox.com. The code for this chapter is divided into the following major examples:

• Snippets_ch7.zip
• Earthquake_ch7.zip

CONNECTING TO THE INTERNET

One of the most powerful aspects of modern smart devices is their ability to connect to Internet services, and to expose the information—or those services—to users within native applications.

This chapter introduces Android’s Internet connectivity model and techniques for downloading and parsing data efficiently. You learn how to connect to an Internet resource and how to use the SAX Parser, XML Pull Parser, and JSON Reader to parse data feeds. Android requires that you perform all network tasks on a background thread, so you learn how to do this efficiently using a combination of View Models, Live Data, and Asynchronous Tasks.

Expanding the earthquake-monitoring example demonstrates how to tie together all these features.

This chapter also introduces the Download Manager, and you learn how to use it to schedule and manage long-running shared downloads. You are also introduced ...