The making of an Android library: Download Manager v2

Android allows developers to add download functionality to their apps, but if you want to extend that behaviour, or customise it to your liking — that’s not easy. That’s why at Novoda we created an improved version of the Download Manager.

This is the perfect example to see how Android developers can share common code between more projects through an Android Library. In this deck I show how to get started creating a library, what are the difficulties we encountered and finally how to publish and share the library between multiple projects.

Transcript

1. The making of an Android library: Download Manager v2 Daniele Bonaldo
2. Daniele Bonaldo
3. Why?
4. Why?
5. Why?
6. Why?
7. Why?
8. Why?
9. Why?
10. How?
11. Extract library code How?
12. Extract library code
13. Dedicated project
14. Libraries repository
15. Fork existing library
16. Fork existing library
17. Novoda’s Download Manager
18. Novoda’s Download Manager • Fork from AOSP Download Manager • Downloads to internal storage • Multiple files grouped in batches • Client app rules for download start/resume
19. Novoda’s Download Manager • Entirely rewritten • Easier batching • More control for client app: • download rules • notifications customisation • storage location • Replaced SQLite with Room • Better API for downloads status querying • Goodbye Content Provider v2
20. Defaults
21. Defaults
22. Defaults
23. Demo app
24. Maintenance
25. Open-source Maintenance
26. Clear readme • Dependency definition • Sample usage • Most common use cases • Important information for first time users
27. Contributions • Be present • Address comments, ask for details if needed • Be opinionated, but 
 evidence-based
28. Issues template .github/ ISSUE_TEMPLATE.md PULL_REQUEST_TEMPLATE.md CONTRIBUTING.md
29. Continuous Integration • Static analysis • Tests • Pull Request Builder • Releases
30. Release
31. Release
32. https://github.com/novoda/bintray-release Novoda bintray-release plugin
33. Semantic versioning 2.1.0 Major Minor Patch
34. Standard release flow 1.0.0 1.1.0-SNAPSHOT Library update Snapshot release Test in client project Issue detected 1.1.0 release
35. Composite builds
36. Standard release flow 1.0.0 1.1.0-SNAPSHOT Library update Test in client project Issue detected 1.1.0 release
37. Automated release • Snapshot releases for develop branch • Public version releases for release branch
38. Conclusions
39. Conclusions • Libraries • Small scope • Prevent coupling • Reuse solutions • Create • Dedicated module • Fork existing one • Generalise / evolve • Demo app! • Open source • Clear readme • Templates • Continuous Integration • Release • Semantic versioning • Composite builds • Automated releases
40. Daniele Bonaldo Thank You! @danybony_ danybony danielebonaldo.com