Android项目架构

从功能需求、设计模式、最佳实践出发考虑

MVP模式

数据、显示、控制解耦，mosby，作者blog1，blog2

依赖注入

数据存储

  • squidb，基于注解，编译期生成DAO类，model类是编译期生成的，而不是定义表结构的类，对复杂SQL语句的支持非常好
  • DBFlow，基于注解，编译期生成DAO类，对关系的支持很好
  • ActiveAndroid，基于注解，运行时转换
  • greenDAO，编译期生成辅助代码
  • StorIO，与rx集成，响应式DBHelper框架

网络连接处理

  • Retrofit，使用动态代理将java接口转化为REST API
  • OkHttp，优化的HTTP client（共享连接，连接池，透明压缩，缓存，重试等），支持web socket协议

异步处理

  • 响应式编程（rx，在java7中使用lambda语法：retrolambda），消息的发出者和响应的接收者在同一模块内，局部性、单对单
  • 事件处理（EventBus，Otto），全局性事件、一对多比较合适

测试

持续集成

  • jenkins-ci，整合代码托管工具，commit、merge request自动触发构建

工具

  • 图片加载
    • Fresco，多来源加载、缓存、内存管理（存放在安卓非堆特殊内存区域）、支持多种格式、多种功能（圆角）
    • Glide，多来源加载、缓存、Object pool内存优化、Context生命周期加载优化、ListView、RecyclerView等加载优化
    • Picasso，使用堆内存，格式稍少
  • 模块热加载
    • dynamic-load-apk，通过代理实现启动、显示、执行安装时未定义的Activity，Service，实现模块热加载
  • 错误统计
    • fabric，提供crash统计、以及twitter集成
  • 调试
    • XLog，函数调用追踪，log出参数、返回值、线程、执行时间，支持方法、类的注解；
    • Fresco，chrome查看log，view heriachy，shared pref，db等；
    • LeakCanary，memory leak检测工具；
  • 时间
    • ThreeTenBP，JSR310的java 8以前的兼容实现，比安卓的Date类等强大无数倍；
    • ThreeTenABP，安卓的一个包装，init过程性能更好；
  • 导航
    • FragmentArgs，Fragment启动时通过Argument传递参数
    • Dart，Activity之间通过Intent传递Extra参数
    • Pocket Knife，Activity的Extra传递参数，SavedInstance做状态保存/恢复
    • Aftermath，A simple, annotation-based Android library for generating onActivityForResult handlers.
  • 动效
    • rebound，通过Android系统的property transition，加上各种变换函数，实现模拟物理的动效；
  • 设计

Develop maintainable apps

  • Libraries
    选择第三方库时的考虑
    • Documentation: 文档是否全面
    • Repository Check-ins(Stability): 稳定性、是否保持维护
    • Fulfils a Need: 满足项目需求
  • Domain design
    • Keep code simple: OO，一个类只负责一件事
    • Use MVC/MVP/MVVM Pattern
    • Functional Test
    • Use the tools: IDE的重构工具很强大
  • Code quality
    • Readability matters
    • 工具
      • CheckStyle
      • Lint
      • Findbugs
      • PMD
    • Refactor Gradually
  • Testing
    • Unit test: Every single line of code that you write should be tested. Peroid. -- Robert Martin
    • Junit(...) + Mockito
    • Continuous Integration
    • Code coverage

Android Clean Architecture

分层结构

clean_architecture1.png

  • Entities: These are the business objects of the application.
  • Use Cases: These use cases orchestrate the flow of data to and from the entities. Are also called Interactors.
  • Interface Adapters: This set of adapters convert data from the format most convenient for the use cases and entities. Presenters and Controllers belong here.
  • Frameworks and Drivers: This is where all the details go: UI, tools, frameworks, etc.
  • Dependency Rule: source code dependencies can only point inwards and nothing in an inner circle can know anything at all about something in an outer circle.

安卓项目层次结构示例

clean_architecture_android.png

使用Rx后的层次结构示例

clean_architecture_evolution.png

  • Presentation layer: UI tests with Espresso 2 and Android Instrumentation.
  • Presenter && View test: 针对接口进行单元测试；对UI简单交互结果逻辑的测试（如：Activity跳转，Fragment切换，相关接口调用）；
  • Domain layer: JUnit + Mockito since it is a regular Java module.
  • Data layer: Migrated test battery to use Robolectric 3 + JUnit + Mockito.

代码组织（包组织）

  • Package by layer
  • Package by feature
    • Higher Modularity
    • Easier Code Navigation
    • Minimizes Scope

Flux Architecture

  • 结构图
    flux-graph-simple.png
    • View: Application interface. It create actions in response to user interactions. Activity or Fragment
    • Dispatcher: Central hub through which pass all actions and whose responsibility is to make them arrive to every Store. An event bus.
    • Store: Maintain the state for a particular application domain. They respond to actions according to current state, execute business logic and emit a change event when they are done. This event is used by the view to update its interface. Simple POJOs with two main attributes: Type: a String identifying the type of event; Data: a Map with the payload for this action.
    • More about Stores
      • Stores contain the status of the application and its business logic.
      • Stores react to Actions emitted by the Dispatcher, execute business logic and emit a change event as result.
      • ...

RxFlux

rxflux_arch.png

What is all this Clean Architecture jibber-jabber about?

基础

  • SOLID
    • Single Responsiblity
    • Open/Closed
    • Liskov Substitution
    • Interface Segregation
    • Dependency Inversion
  • Abstraction
    • 面向接口编程
    • 高内聚，低耦合
      • 内聚：单一模块内，各个部分之间的关系
      • 耦合：各个模块之间的关系
  • Vertical slicing
    • Horizontal slicing：传统方式，从服务提供方分包，例如DB, Network, ui...
    • Vertical slicing：源自敏捷，根据功能（use case）进行分包，而将与该功能相关的db, network, ui等部分放到同一个模块中

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