Google I/O 2021 Android精华内容

google i/o 2021结束了, 都有什么精彩内容呢?
android部分的playlist附上: android & play at google i/o 2021

developer keynote (google i/o '21)

对于android的部分来说, 主要是:

android 12

• user safety.
• performance; improved app startup; customizable launch animations.
• user experience; widgets.

create beautiful apps, easier

现代化的android开发.

• android studio的升级.
• kotlin: kotlin symbol processing.
• jetpack: 各种libraries和compose.

build across screens.

• 各种屏幕.
• voice.
• watches: health services.

the top 3 things to know in modern android development | android @ google i/o'21

android开发的三个top topic:

• jetpack: 一系列的jetpack libraries发布了新版.

• tooling: android studio的升级, 有了workmanager inspector, ui的inspector支持了view和compose.
• kotlin.

what's new in android | keynote

android 12 -> s.

• @deprecated -> deprecated.
• color.
• widgets.
• launch animations: 系统自带启动动画, 可以定制.
• notifications: 新的template style; trampoline(?) 优化点开notification的那个短暂延迟.
• toasts: 带icon, 说明是哪个app弹的toasts; 控制个数.
• picture in picture的改善.
• imageview有个setrendereffect可以模糊照片了.
• 可以用theme定制模糊.

• list的弹力拉伸效果. (我自己起的名字, 其实人家叫stretch overscroll).
• graphics: avif. 可以过滤支持的media类型.
• privacy: 关于permission的一些改进; 剪贴板内容会有toast说明来源; foreground restrictions.

what’s new in android development tools | session

android studio版本号设计.

• preview工具可以设置横屏, 定制尺寸, 显示blueprints, play animation. compose的preview有交互模式.
• accessibility test framework scanner.
• 适配多种屏幕: layout validation.
• 折叠屏, 手表.
• 模拟器还可以模拟heart rate.
• snapshots test.
• workmanager的tasks.
• migrate to non-transitive r classes...

what’s new in jetpack | session

解释了jetpack的初衷和现状.
alpha和beta版本的意思.

• experimental annotations -> stable.
• camerax -> stable.
• appsearch -> alpha.
• datastore -> 用来取代sharedpreferences.

• security crypto -> stable.
• hilt -> stable.
• workmanager -> stable. (android studio也推出了新的workmanager inspector.)
• room -> stable.

• constraintlayout -> stable. motionlayout + motion editor.
• fragment -> stable.
  (详见release notes:
  重建了fragmentmanager; 新增了get result的callback; 废弃了一些api, 并且fragment strictmode可以检测项目中是否还在使用.
• navigation -> alpha. 现在支持多个backstacks.
• google shortcuts -> alpha.
• emojicompat -> alpha. (appcompat 1.4.0以后默认包含.)
• paging -> stable.
• macrobenchmark -> alpha. (app启动和滚动效率; local/ci.)
• compose integrations.

what's new in jetpack compose | session

为什么我们需要一个全新的ui toolkit呢. -> 为了适应更加现代化的开发方式.

faster & easier.

compose将数据转换成ui.

checkbox的例子:

ui完全由参数控制. -> single source of truth. 没有其他的状态需要sync.

把参数和回调提到方法参数中去:

• you completely describe your ui for a given state.
• the framework updates your ui when the state changes.

这里有个图, 推荐viewmodel暴露一个screen状态, 集中管理, 然后下发到每个composable.

这样也利于测试.

compose实现了material design, 提供了组件, 还有theming system.

有一个owl app的实现解说.

和传统view的interop.

state of kotlin on android | session

• kotlin变得越来越流行, 不仅app, 还有server.
• kotlin symbol processing目前发布了alpha.
• 编译器的升级.
• 好多好多的ktx库.
• protobuf的支持:
• coroutines的debugger -> coming soon. 可以在线程之间跳转, 查看信息.

what’s new in android gradle plugin | session

new apis in the android gradle plugin

using jetpack libraries in compose | session

jetpack compose和jetpack中其他库可以很好的结合使用.

top 12 tips to get ready for android 12 | session

getting ready for android 12.

• developer options -> app compatibility changes.
• foreground services were designed for multi-tasking and completing a user action. -> 从后台启动foreground services将被限制.
• expedited jobs with workmanager apis.
• user may turn off the mic and camera sensors using mic and camera toggles.
• apps that have not been used for an extended period will be hibernated. (permissions, storage, services)
• nearby device permission. decouple bluetooth scanning from location.
• mac address restriction.
• safe component exporting. 有intent filter就必须显式声明exported.
• custom notifications deprecation.
• app link improvements.
• webview samesite.
• new stretch overscroll.