Android App Modular Development Practice: A Comprehensive Guide

This article provides a comprehensive introduction to modular development for Android applications, based on the real-world experience of transforming the vivo official app into a modular architecture.

1. What is Modular Development

Modular development divides an app into multiple independent code modules based on business functions. The article distinguishes between two key concepts: components (single functional units like login or sharing) and modules (independent business units like e-commerce or community features). Two implementation patterns exist: single-project multi-module and multi-project mode. The latter offers significant advantages in code management, debugging, and parallel development, making it suitable for large apps with multiple business lines.

2. Why Adopt Modular Development

Single-project development faces several challenges: low team collaboration efficiency due to code conflicts, high code maintenance costs from tight coupling, and slow compilation times. Modular development addresses these by enabling independent development of each module in separate repositories, reducing code coupling, and allowing faster compilation during development phases.

3. Modular Architecture Design

The architecture follows two dimensions: vertical layering and horizontal module division. Vertically, the app is divided into three layers: business layer (top), component layer (middle), and basic framework layer (bottom). Horizontally, modules are split based on business or functional boundaries. Key dependency rules include: upper layers can depend on lower layers, but not vice versa; modules at the same level cannot depend on each other.

4. Technical Solutions

The article addresses common challenges: independent development and debugging using separate App and Library modules; page navigation using the ARouter framework for Activity and Fragment routing; inter-module method calls via ARouter services; and data/event passing using ARouter services or EventBus.

5. Transforming Legacy Projects

The transformation follows a "top-down division, bottom-up extraction" approach. Steps include: business module analysis, extracting common components, splitting business modules, splitting functional modules, code decoupling, and managing coexistence of old and new code. The process requires patience and should be done incrementally.