Apm29's Studio.

用Flutter重构应用

字数统计: 5.9k阅读时长: 28 min
2019/12/23 Share

前言

开发环境

  • macOS Catalina10.15.2
  • AndroidStudio 3.5.3
  • Xcode 11.3
  • 看看doctor
    $ flutter doctor -v
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    [✓] Flutter (Channel master, v1.13.6-pre.16, on Mac OS X 10.15.2 19C57, locale zh-Hans-CN)
    • Flutter version 1.13.6-pre.16 at /Users/ciih/flutter
    • Framework revision fcaf9c4070 (34 hours ago), 2019-12-21 14:03:01 -0800
    • Engine revision 33813929e3
    • Dart version 2.8.0 (build 2.8.0-dev.0.0 886615d0f9)


    [✓] Android toolchain - develop for Android devices (Android SDK version 28.0.3)
    • Android SDK at /Users/ciih/Library/Android/sdk
    • Android NDK location not configured (optional; useful for native profiling support)
    • Platform android-29, build-tools 28.0.3
    • Java binary at: /Applications/Android Studio.app/Contents/jre/jdk/Contents/Home/bin/java
    • Java version OpenJDK Runtime Environment (build 1.8.0_202-release-1483-b49-5587405)
    • All Android licenses accepted.

    [✓] Xcode - develop for iOS and macOS (Xcode 11.3)
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Xcode 11.3, Build version 11C29
    • CocoaPods version 1.9.0.beta.2

    [✓] Chrome - develop for the web
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

    [✓] Android Studio (version 3.5)
    • Android Studio at /Applications/Android Studio.app/Contents
    • Flutter plugin version 42.1.1
    • Dart plugin version 191.8593
    • Java version OpenJDK Runtime Environment (build 1.8.0_202-release-1483-b49-5587405)

    [✓] IntelliJ IDEA Community Edition (version 2019.1.3)
    • IntelliJ at /Applications/IntelliJ IDEA CE.app
    • Flutter plugin version 39.0.3
    • Dart plugin version 191.8593

    [✓] VS Code (version 1.39.2)
    • VS Code at /Applications/Visual Studio Code.app/Contents
    • Flutter extension version 3.6.0

    [✓] Connected device (3 available)
    • 钱水利的 iPhone • 46e7963e6f0f38edf5c1c78f2f782a814f1edb34 • ios • iOS 13.3
    • Chrome • chrome • web-javascript • Google Chrome 79.0.3945.88
    • Web Server • web-server • web-javascript • Flutter Tools

    • No issues found!

项目创建

为了省事直接用AndroidStudio创建了

命令行创建项目

  • 简单创建

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    $ flutter create [项目名称]
  • -t [模板名称]可以指定对应的模板,现在可以创建app–应用 module–app的模块 package–纯Dart代码项目 plugin–flutter插件项目

  • -i [swift/objc] 设置iOS开发语言,swift或者oc

  • -a [kotlin/java] 设置Android开发语言

  • --[no-]androidx 指定要不要使用Androidx支持库

设置子模块

运行flutter create --project-name [你的项目名称] -i swift -a kotlin --androidx 之后项目根目录大概是这个样子滴

  • android android端代码
  • ios ios端代码
  • web web端代码
  • test 测试代码
  • lib 存放Dart代码
  • pubspec.lock
  • pubspec.yaml 依赖文件,类似于Android的gradle或者Vue.js里面的package.json

完成之后需要将项目纳入版本控制,但是ios/web/android三个文件夹需要作为子模块(git submodule)
首先在github或者其他git网站新建子模块的repo(空的仓库),然后分别进入ios/web/android目录,
$ git init 初始化本地git仓库
$ git remote add origin [你的子模块仓库地址] 设置远程仓库地址
$ git commit -ma "init" 提交所有文件到本地仓库
$ git push -u origin master 推送本地代码到远程仓库

然后在git网站新建你的总repo,在根目录下初始化git仓库
然后添加子模块git submodule add [子模块仓库链接] [名称] ,注意名称要改成ios/android/web等,和本地目录名称对应起来,然后也是提交
$ git remote add origin [你的仓库地址]
$ git commit -ma "init"
$ git push -u --recurse-submodules=on-demand origin master 推送本地代码到远程仓库
不出意外的话你的git仓库看起来是这样的
image.png

子模块设置完成,如果需要更新子模块/拉取服务端改动等,可以参考git子模块那篇文章

项目框架搭建

从状态管理,路由管理,视图组件,动画,网络组件,本地存储,硬件交互等方面搭建新项目,尽量选择侵入性小的库

状态管理

之前的项目在状态管理方面用过BLoCProvider,新的项目想试一试flutter_redux,fish_redux看了下太复杂了,小项目可能不太合适,有种大炮打蚊子的感觉…

flutter_redux 基本概念

redux的基本概念:

  • store 状态管理
  • state 应用/数据状态
  • action view发出的动作
  • reducer 一个接收state,action返回新的state的函数
  • middleware 在action和reducer中间执行

redux的Store

flutter_redux依赖于redux包,所以我们也要先了解了redux里面的概念,Store是整个App的状态Owner,唯一能改变Store中状态树的方法就是通过Store发送(dispatch)一个Action,action会先通过middleware,如果没有被middleware中断,则会传递至reducer,reducer根据action改变store中的state完成state树的更新,当然具体逻辑可能更复杂一些.

- 定义action: `final increment = 'INCREMENT';`
- 定义reducer: `int counterReducer(int state, action) => state+1` 只可以根据action来决定如何改变state,我这里为了简单就直接写个加一了
- 创建Store: `Store<int>(counterReducer,initialState:0)`
- 分发一个action: `store.dispatch(increment);` action可以是任意类型
- 然后store中的state(原来是0)就会改变

store提供了两种方式获得state实例:state属性 或者 onChange提供的Stream

看看构造方法全都明白了:

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Store(
this.reducer, {
State initialState,
//middleware集合
List<Middleware<State>> middleware = const [],
//是否使用同步的Stream控制器(一般就false)
bool syncStream = false,

/// 若设置为true,在原来State和reducer处理过的State相同的情况下Store不会发送事件
bool distinct = false,
}) : _changeController = StreamController.broadcast(sync: syncStream) {
_state = initialState;
//创建分发器
_dispatchers = _createDispatchers(
middleware,
_createReduceAndNotify(distinct),
);
}

_createDispatchers: 创建一个NextDispatcher集合,放入middleware集合转换来的NextDispatcher,再放入_createReduceAndNotify转化来的NextDispatcher,这个集合就是dispatch方法的调用栈,dispatch方法会先调用第一个NextDispatcher

  • 再看看Middleware的定义
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    typedef dynamic Middleware<State>(
    Store<State> store,
    dynamic action,
    NextDispatcher next,
    );

    这里的NextDispatcher是对reducer和middleware的简单包装,让他们接受action并返回action(或者被拦截…所以定义里面返回值是dynamic)

因为middleware都在栈顶,所以先调用middleware转换成的NextDispatcher,这个next就是下一个middleware或者reducer对应的NextDispatcher,若你在middleware中调用了next,这个调用链就会一直调用到最后知道reducer调用完成,完成对state的修改.(这个是不是叫责任链设计模式?)

来个图 middleware–> middleware(我可以中断也可以往下传球) —> …. —>reducer

reducer完成了拼图的最后一块,最后的NextDispatcher,往StreamController(_changeController)add了一个修改后的state.看到这里恍然大悟,原来又是你:Stream,所以很好猜,下面章节要讲的Widget里用于局部更新的StoreConnector/StoreBuilder应该就是StreamBuilder包装下的东西.

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NextDispatcher _createReduceAndNotify(bool distinct) {
return (dynamic action) {
final state = reducer(_state, action);

if (distinct && state == _state) return;

_state = state;
_changeController.add(state);
};
}

flutter_redux的组件:

  • StoreProvider store的提供者,类似于Proivder中各种Provider的概念
  • StoreConnector 类似于Provider中Consumer,响应变化.包含两个@require的函数:
    • converter,用于将state转化为view_model
    • builder,view_model转为view(widget)
    • onInit:初始化操作

StoreProvider

继承自InheritedWidget,用于给所有子不见提供Store,里面有用的就一个Store对象,和其他状态管理组件例如Provider一样,有个静态方法static Store<S> of<S>(BuildContext,{bool listen=true})来获取实例. 几乎一模一样的参数.

  • 当该方法传入listen = true
    通过inheritFromWidgetOfExactType(这个方法在1.12已经被标记为deprecated,新的api是dependOnInheritedWidgetOfExactType,名字与意义更符合一点)获取provider,api文档说的很明显,会把调用者context注册,当该Type对应的InheritedWidget发生改变的时候将会rebuild该context对应的组件

  • listen = false
    通过ancestorInheritedElementForWidgetOfExactType(这个方法在1.12已经被标记为deprecated,新的api是getElementForInheritedWidgetOfExactType,)获取provider,文档说的是获取给定的Type最近的InheritedElement,然后再通过InheritedElement拿到InheritedWidget,也就是我们需要的provider.

  • 源码大概结构

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    class StoreProvider<S> extends InheritedWidget {
    final Store<S> _store;

    /// 通过Store和Child创建
    const StoreProvider({
    Key key,
    @required Store<S> store,
    @required Widget child,
    }) : assert(store != null),
    assert(child != null),
    _store = store,
    super(key: key, child: child);

    ///用于获取Store实例,在initState中使用时要传listen = false
    static Store<S> of<S>(BuildContext context, {bool listen = true}) {
    final type = _typeOf<StoreProvider<S>>();
    final provider = (listen
    ? context.inheritFromWidgetOfExactType(type)
    : context
    .ancestorInheritedElementForWidgetOfExactType(type)
    ?.widget) as StoreProvider<S>;

    if (provider == null) throw StoreProviderError(type);

    return provider._store;
    }

    // Dart中获取类型的方法,很多地方会用到
    static Type _typeOf<T>() => T;

    ///是否需要通知子Widget的判断方法
    @override
    bool updateShouldNotify(StoreProvider<S> oldWidget) =>
    _store != oldWidget._store;
    }

StoreConnector

这个类似于Provider中的Consumer,class StoreConnector<S, ViewModel> extends StatelessWidget {},泛型S表示State类型,ViewModel表示从State类型转化来的model数据,用于生成Widget.这个组件实际只是给已给名叫__StoreStreamListener的StatefulWidget包装了下.我们先看看它的State干了什么能监听Store内的State变化.

1.两个重要的属性

  • Stream stream;
  • ViewModel latestValue;

2.initState方法

  • 调用StoreConnector的onInit
  • 在下一帧调用StoreConnector的onInitialBuild
  • 通过StoreConnector的converter吧store转换成viewModel赋值给 latestValue
  • 通过StoreConnector.store.onChange属性获得流(Stream),经过一系列操作转换成ViewModel流赋值给属性stream
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    stream = widget.store.onChange
    .where(_ignoreChange)
    .map(_mapConverter)
    // Don't use `Stream.distinct` because it cannot capture the initial
    // ViewModel produced by the `converter`.
    .where(_whereDistinct)
    // After each ViewModel is emitted from the Stream, we update the
    // latestValue. Important: This must be done after all other optional
    // transformations, such as ignoreChange.
    .transform(StreamTransformer.fromHandlers(handleData: _handleChange));

    void _handleChange(ViewModel vm, EventSink<ViewModel> sink) {
    if (widget.onWillChange != null) {
    widget.onWillChange(latestValue, vm);
    }

    latestValue = vm;

    if (widget.onDidChange != null) {
    WidgetsBinding.instance.addPostFrameCallback((_) {
    widget.onDidChange(latestValue);
    });
    }

    sink.add(vm);
    }

    这里有几个Stream操作符:where是筛选,map是映射,transform 方法就是把一个 Stream 作为输入,然后经过计算或数据转换,输出为另一个 Stream。另一个 Stream 中的数据类型可以不同于原类型,数据多少也可以不同

所以其他方法都并不重要了,_createStream方法以及定义好了流中数据转换和过滤的方式,其他方法都是一些生命周期回调方便定制其他功能,最后看看build方法做了些什么事:

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@override
Widget build(BuildContext context) {
return widget.rebuildOnChange
? StreamBuilder<ViewModel>(
stream: stream,
builder: (context, snapshot) => widget.builder(
context,
latestValue,
),
)
: widget.builder(context, latestValue);
}

没错!!!包装了下StreamBuilder,通过它监听Stream中的新数据,返回builder创建的新Widget.

StoreBuilder

其实和StoreConnector差不多,懒人版本的StoreConnector,少了个converter,state–>viewModel这部分就省了,直接build完事.其他功能都一毛一样.

Redux包下提供的工具方法

redux包提供了一些工具类工具方法,让我免去大量switch..case模板代码

比如说我们先定义state和action

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class AppState {
final List<Item> items;
AppState(this.items);
}
class LoadItemsAction {}
class UpdateItemsAction {}
class AddItemAction{}
class RemoveItemAction {}
class ShuffleItemsAction {}
class ReverseItemsAction {}
class ItemsLoadedAction<Item> {
final List<Item> items;
ItemsLoadedAction(this.items);
}

我们现在有一个state保存一个item集合,有加载,更新,添加,删除等许多action,如果是之前的代码我们可能要写好多switch..case代码,像下面这样👇:

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final appReducer = (AppState state, action) {
if (action is ItemsLoadedAction) {
return new AppState(action.items);
} else if (action is UpdateItemsAction) {
return ...;
} else if (action is AddItemAction) {
return ...;
} else if (action is RemoveItemAction) {
return ...;
} else if (action is ShuffleItemsAction) {
return ...;
} else if (action is ReverseItemsAction) {
return ...;
} else {
return state;
}
};

redux提供了combineReducer方法和TypedReducer类来将多个小的reducer组合为一个reducer:

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final removeItemReducer = (AppState state, RemoveItemAction action) {
return ...;
}

///....

final Reducer<AppState> appReducer = combineReducers([
new TypedReducer<AppState, LoadTodosAction>(loadItemsReducer),
new TypedReducer<AppState, UpdateItemsAction>(updateItemsReducer),
new TypedReducer<AppState, AddItemAction>(addItemReducer),
new TypedReducer<AppState, RemoveItemAction>(removeItemReducer),
new TypedReducer<AppState, ShuffleItemAction>(shuffleItemsReducer),
new TypedReducer<AppState, ReverseItemAction>(reverseItemsReducer),
]);

middleware当然也有:

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final List<Middleware<AppState>> middleware = [
new TypedMiddleware<AppState, LoadTodosAction>(loadItemsMiddleware),
new TypedMiddleware<AppState, AddTodoAction>(saveItemsMiddleware),
new TypedMiddleware<AppState, ClearCompletedAction>(saveItemsMiddleware),
new TypedMiddleware<AppState, ToggleAllAction>(saveItemsMiddleware),
new TypedMiddleware<AppState, UpdateTodoAction>(saveItemsMiddleware),
new TypedMiddleware<AppState, TodosLoadedAction>(saveItemsMiddleware),
];

路由管理

路由管理使用fluro,其实flutter框架自带的路由已经很好了,不过fluro可以往路由路径里加入参数,这个有些项目比较方便,可以自己取舍.

引入

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dependencies:
fluro: ^1.5.1

使用

提供一个全局Router实例

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import 'package:fluro/fluro.dart';

class Application{

static Router router;

static void init() {
Router router = Router();
Routes.configureRoutes(router);
Application.router = router;
}
}

定义一个路由映射类

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class Routes {
static String root = "/";
static String home = "/home";
static String login = "/login";
static String personalSettings = "/personal_settings";

static void configureRoutes(Router router) {
router.notFoundHandler = new Handler(handlerFunc: (
BuildContext context,
Map<String, List<String>> params,
) {
print("ROUTE WAS NOT FOUND !!!");
return NotFoundPage();
});

/// 第一个参数是路由地址,第二个参数是页面跳转和传参,第三个参数是默认的转场动画,可以看上图
router.define(root, handler: splashHandler);
router.define(home, handler: homeHandler);
router.define(login, handler: loginHandler);
router.define(personalSettings, handler: personalSettingsHandler);
}
}

可以看到我设置了四个路径,'/'为默认第一个页面,configureRoutes手动在main方法中调用来初始化Router,我给他设置了一个404页面,然后定义了各个路由的handler:

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class NotFoundPage extends StatelessWidget {
@override
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: Text('404 路由未找到'),
),
);
}
}

/// 跳转到首页Splash
final splashHandler = new Handler(
handlerFunc: (BuildContext context, Map<String, List<String>> params) {
return SplashPage();
},
);

final homeHandler = new Handler(
handlerFunc: (BuildContext context, Map<String, List<String>> params) {
return HomePage();
},
);

final personalSettingsHandler = new Handler(
handlerFunc: (BuildContext context, Map<String, List<String>> params) {
return PersonalSettingsPage();
},
);

final loginHandler = new Handler(
handlerFunc: (BuildContext context, Map<String, List<String>> params) {
return LoginPage();
},
);

然后在main.dart中先调用下init:

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Future<void> main() async {
WidgetsFlutterBinding.ensureInitialized();
// 初始化缓存,这个是自己包装的SharedPreferences工具
await Cache().init();
// 注册 fluro routes
Application.init();
runApp(FlutterReduxApp());
}

然后就可以在其他地方使用了,当然你也可以再封装个路由跳转类:

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Application.router.navigateTo(
context,
Routes.personalSettings,
transition: TransitionType.inFromBottom,
);

路由跳转类:(这边基本没用到参数…只支持String参数并且不能有中文),fluro可以定义转场动画,需要的可以去看看Github:fluro

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class AppRouter {
static Future toHomeAndReplaceSelf(BuildContext context) {
return Application.router.navigateTo(context, Routes.home, replace: true);
}

static Future toPersonal(BuildContext context) {
return Application.router.navigateTo(
context,
Routes.personalSettings,
transition: TransitionType.inFromBottom,
);
}

static Future toHome(BuildContext context, ActiveTab activeTab) {
store.dispatch(TabSwitchAction(activeTab.index, context));
return Application.router
.navigateTo(context, Routes.home, replace: true, clearStack: true);
}

static Future toLogin(BuildContext context) {
return Application.router.navigateTo(
context,
Routes.login,
transition
: TransitionType.inFromBottom,
);
}
}

定义参数是这样的:

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var usersHandler = Handler(handlerFunc: (BuildContext context, Map<String, dynamic> params) {
return UsersScreen(params["id"][0]);
});

void defineRoutes(Router router) {
router.define("/users/:id", handler: usersHandler);

// it is also possible to define the route transition to use
// router.define("users/:id", handler: usersHandler, transitionType: TransitionType.inFromLeft);
}

国际化

如果您的应用可能会给另一种语言的用户使用,那么您需要“国际化”它。这意味着您在编写应用程序时需要为应用程序支持的每种语言环境, 设置“本地化”的一些值,如文本和布局。Flutter提供一些widgets和类,以帮助实现国际化,而Flutter的库本身也是国际化的。
参考:Flutter中文网,Flutter-国际化适配

导入flutter_localization包

pubspec.yml文件:

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dependencies:
flutter:
sdk: flutter
flutter_localizations:
sdk: flutter

引入

指定MaterialApplocalizationsDelegatessupportedLocales

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import 'package:flutter_localizations/flutter_localizations.dart';

new MaterialApp(
localizationsDelegates: [
// ... app-specific localization delegate[s] here
GlobalMaterialLocalizations.delegate,
GlobalWidgetsLocalizations.delegate,
],
supportedLocales: [
const Locale('en', 'US'), // English
const Locale('he', 'IL'), // Hebrew
// ... other locales the app supports
],
// ...
)

使用Flutter-i18n插件

如果你已经成功安装插件,打开项目后,会发现自动添加以下两个文件:

lib/generated/i18n.dart 主要的国际化文件,主要使用的类为S
res/values/string_en.arb 该文件主要适配英文语言,内容为json格式
修改:

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MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.red,
),
localizationsDelegates: const [
S.delegate,
GlobalMaterialLocalizations.delegate,
GlobalWidgetsLocalizations.delegate
],
supportedLocales: S.delegate.supportedLocales,
);
  • localizationsDelegates本地化委托参数
  • S.delegate 我们项目的本地化委托类,这个你不用管,他会根据你的arb文件自动生成对应的函数
    GlobalMaterialLocalizations.delegate和GlobalWidgetsLocalizations.delegate为
  • flutter_localizations插件包提供的委托,如果你使用MaterialApp这个部件的- - GlobalMaterialLocalizations.delegate这个可以不用
  • supportedLocales支持的本地化
  • S.delegate.supportedLocales我们项目支持的本地化,这个你不用管,它会在你添加arb文件时自动更新你的支持的本地化

声明资源

.arb文件

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{
"title":'AppName'
}

占位符:

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{
"successMessage":"操作成功:$action"
}

列表: 支持语法为:key+zero/one/two/few/many/other

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{
"selectZero":"没有了",
"selectOne":"一个",
"selectTwo":"两个",
"selectFew":"一些",
"selectMany":"很多",
"selectOther":"其它"
}

使用资源

  • 普通:S.of(context).title
  • 带占位符:S.of(context).successMessage("登录")
  • 列表
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    S.of(context).select(0);//零个
    S.of(context).select(1);//一个
    S.of(context).select("many");//多个
    S.of(context).select(null);//其它

插件的使用

camera 0.5.7+2

引入

pubspec.yml:

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camera: ^0.5.7+2

iOS权限

info.plist

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<key>NSCameraUsageDescription</key>
<string>APP需要您的同意,才能访问相机进行拍照,如禁止将无法拍照更新信息</string>
<key>NSMicrophoneUsageDescription</key>
<string>APP需要您的同意,才能访问麦克风进行录音,如禁止将无法录音发送语音信息</string>

获取Camera

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List<CameraDescription> cameras = await availableCameras();

使用

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class CameraApp extends StatefulWidget {
@override
_CameraAppState createState() => _CameraAppState();
}

class _CameraAppState extends State<CameraApp> {
CameraController controller;

@override
void initState() {
super.initState();
controller = CameraController(cameras[0], ResolutionPreset.medium);
controller.initialize().then((_) {
if (!mounted) {
return;
}
setState(() {});
});
}

@override
void dispose() {
controller?.dispose();
super.dispose();
}

@override
Widget build(BuildContext context) {
if (!controller.value.isInitialized) {
return Container();
}
return AspectRatio(
aspectRatio:
controller.value.aspectRatio,
child: CameraPreview(controller));
}
}

Widget使用

ClipPath

ClipPath传入一个Clipper,和Child,Clipper将会用getClip返回的path来裁剪Child

示例:

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import 'package:axj_app/generated/i18n.dart';
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:camera/camera.dart';

List<CameraDescription> cameras;

class AuthPage extends StatefulWidget {
@override
_AuthPageState createState() => _AuthPageState();
}

class _AuthPageState extends State<AuthPage> {
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(S.of(context).authTitle),
actions: <Widget>[
IconButton(
icon: Icon(Icons.switch_camera),
onPressed: () {
switchCamera();
})
],
),
body: cameraReady && controllerReady
? Stack(
children: <Widget>[
Align(
alignment: Alignment.center,
child: ClipPath(
clipBehavior: Clip.antiAlias,
clipper: FaceClipper(),
child: AspectRatio(
aspectRatio: controller.value.aspectRatio,
child: CameraPreview(controller),
),
),
)
],
)
: Center(
child: Column(
mainAxisSize: MainAxisSize.min,
children: <Widget>[
CupertinoActivityIndicator(),
SizedBox(height: 32),
Text(S.of(context).loadingCameraHint)
],
),
),
);
}

CameraController controller;

bool get cameraReady => cameras != null && cameras.isNotEmpty;

bool get controllerReady => controller?.value?.isInitialized ?? false;

int currentCameraIndex = 1;

@override
void initState() {
() async {
if (!cameraReady) {
cameras = await availableCameras();
}
await initializeCameraController();
}();
super.initState();
}

@override
void dispose() {
controller?.dispose();
super.dispose();
}

void switchCamera() {
if (!cameraReady) {
return;
}
currentCameraIndex += 1;
if (currentCameraIndex == cameras.length) {
currentCameraIndex = 0;
}
initializeCameraController();
}

Future initializeCameraController() async {
setState(() {});
controller =
CameraController(cameras[currentCameraIndex], ResolutionPreset.high);
await controller.initialize();
await Future.delayed(Duration(milliseconds: 400));
if (!mounted) {
return;
}
setState(() {});
}
}

class FaceClipper extends CustomClipper<Path> {
@override
Path getClip(Size size) {
var path = Path();

Rect faceRect =
Rect.fromLTWH(20, 20, size.width - 40, (size.width - 40) * 1.3);

path.moveTo(faceRect.topCenter.dx, faceRect.topCenter.dy);

Offset p1 = faceRect.topRight.translate(0, 0);
Offset p2 = faceRect.centerRight.translate(-10, 0);

path.quadraticBezierTo(p1.dx, p1.dy, p2.dx, p2.dy);

p1 = faceRect.bottomRight.translate(-30, -25);
p2 = faceRect.bottomCenter.translate(10, 0);

path.quadraticBezierTo(p1.dx, p1.dy, p2.dx, p2.dy);
p2 = faceRect.bottomCenter.translate(-10, 0);
path.lineTo(p2.dx, p2.dy);

p1 = faceRect.bottomLeft.translate(30, -25);
p2 = faceRect.centerLeft.translate(10, 0);

path.quadraticBezierTo(p1.dx, p1.dy, p2.dx, p2.dy);

p1 = faceRect.topLeft.translate(0, 0);
p2 = faceRect.topCenter.translate(0, 0);

path.quadraticBezierTo(p1.dx, p1.dy, p2.dx, p2.dy);

var rightEarRect = Rect.fromLTWH(
faceRect.centerRight.dx - 20,
faceRect.centerRight.dy - 35,
20,
60,
);
path.addArc(rightEarRect, -pi / 2, pi);

path.addPolygon([
rightEarRect.bottomCenter,
rightEarRect.bottomLeft,
rightEarRect.topCenter,
], true);

var leftEarRect = Rect.fromLTWH(
faceRect.centerLeft.dx,
faceRect.centerLeft.dy - 35,
20,
60,
);
path.addArc(
leftEarRect,
pi / 2,
pi);

path.addPolygon([
leftEarRect.topCenter,
leftEarRect.bottomRight,
leftEarRect.bottomCenter,
], true);

path.close();
return path;
}

@override
bool shouldReclip(CustomClipper oldClipper) {
return false;
}
}

用ClipPath和自定义的CustomClipper裁剪了个人脸(大概吧.都是凑出来的)


简单封装

Dio简单封装

之前的项目使用过Dio作为网络请求的框架,使用起来比较友好,因为是FlutterChina维护的项目,看文档和提issue都比较方便. 现在最新的版本是3.0,比我刚接触的时候成熟了不少,已经支持Multiple-part File,Post二进制流数据等功能.

我们先搞一个单例,方便全局修改dio的配置

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class Api {
Api._() {
init();
}

static bool printLog = true;
static Api _instance;

static Api getInstance() {
if (_instance == null) {
_instance = Api._();
}
return _instance;
}

factory Api() {
return getInstance();
}

Dio _dio;

void init() {
_dio = Dio(BaseOptions(
method: "POST",
connectTimeout: 10000,
receiveTimeout: 20000,
baseUrl: BaseUrl,
));
_dio.interceptors.add(DioLogInterceptor());
}
}

如图,隐藏主构造函数,提供一个没名字的工厂方法,这样获取实例的方式被简化为Api()

_init方法只执行一次,初始化Dio实例,给他配好默认方法,超时参数,还有baseUrl,然后加入了一个日志拦截器(自己写的,比较简单),方便Debug,

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_dio = Dio(BaseOptions(
method: "POST",
connectTimeout: 10000,
receiveTimeout: 20000,
baseUrl: BaseUrl,
));
_dio.interceptors.add(DioLogInterceptor());

再定义一个请求返回值的模板类

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class BaseResp<T> {
String status;
T data;
String token;
String text;

BaseResp(this.status, this.data, this.token, this.text);

bool get success => status == "1";
}

在Api类中加入Post方法的封装:

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Future<BaseResp<T>> post<T>(
String path, {
@required JsonProcessor<T> processor,
Map<String, dynamic> formData,
CancelToken cancelToken,
ProgressCallback onReceiveProgress,
ProgressCallback onSendProgress,
useFormData: false,
}) async {
assert(processor != null);
processor = processor ?? (dynamic raw) => null;
formData = formData ?? {};
cancelToken = cancelToken ?? CancelToken();
onReceiveProgress = onReceiveProgress ??
(count, total) {
///默认接收进度
};
onSendProgress = onSendProgress ??
(count, total) {
///默认发送进度
};
Response resp = await _dio.post(
path,
options: RequestOptions(
responseType: ResponseType.json,
headers: {
AuthorizationHeader: Cache().token,
},
contentType: useFormData
? ContentTypeFormDataValue
: ContentTypeFormUrlEncodeValue,
data: useFormData ? FormData.fromMap(formData) : formData,
),
cancelToken: cancelToken,
onSendProgress: onSendProgress,
onReceiveProgress: onReceiveProgress,
);
dynamic map;
if (resp.headers
.value(ContentTypeHeader)
.contains(ContentTypeTextPlainValue)) {
map = json.decode(resp.data);
} else {
map = resp.data;
}
dynamic status = map["status"];
dynamic text = map["text"];
dynamic token = map["token"];
dynamic _rawData = map["data"];
T data;
try {
if (status.toString() == '1') data = processor(_rawData);
} catch (e, s) {
print(e);
print(s);
}
return BaseResp<T>(
status.toString(), data, token.toString(), text.toString());
}

Future<BaseResp<T>> get<T>(
String path, {
@required JsonProcessor<T> processor,
Map<String, dynamic> queryMap,
CancelToken cancelToken,
ProgressCallback onReceiveProgress,
}) async {
assert(processor != null);
processor = processor ?? (dynamic raw) => null;
queryMap = queryMap ?? {};
cancelToken = cancelToken ?? CancelToken();
onReceiveProgress = onReceiveProgress ??
(count, total) {
///默认接收进度
};
Response resp = await _dio.get(
path,
queryParameters: queryMap,
options: RequestOptions(
responseType: ResponseType.json,
headers: {
AuthorizationHeader: Cache().token,
},
queryParameters: queryMap,
contentType: ContentTypeFormUrlEncodeValue),
cancelToken: cancelToken,
onReceiveProgress: onReceiveProgress,
);
dynamic map;
if (resp.headers
.value(ContentTypeHeader)
.contains(ContentTypeTextPlainValue)) {
map = json.decode(resp.data);
} else {
map = resp.data;
}
dynamic status = map["status"];
dynamic text = map["text"];
dynamic token = map["token"];
dynamic _rawData = map["data"];
T data;
try {
if (status.toString() == '1') data = processor(_rawData);
} catch (e,s) {
print(e);
print(s);
}
return BaseResp<T>(
status.toString(), data, token.toString(), text.toString());
}

当然还有定义好json数据处理函数

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typedef JsonProcessor<T> = T Function(dynamic json);

FutureBuilder与网络请求

FutureBuilder是Flutter Framework中提供的异步构建视图的一个Widget,提供给它一个Future类型的数据,它会执行future任务封装成AsyncSnapshot返回,并在error,success情况下rebuild.我们的网络工具一般都是封装成async方法,也就是返回值为Future的方法,我们可以给网络请求到视图显示这一步加入转场特效还有错误处理/重试功能.

首先我们的FutureBuilder

CATALOG
  1. 1. 前言
  2. 2. 开发环境
  3. 3. 项目创建
    1. 3.1. 命令行创建项目
    2. 3.2. 设置子模块
  4. 4. 项目框架搭建
    1. 4.1. 状态管理
      1. 4.1.1. flutter_redux 基本概念
      2. 4.1.2. redux的Store
      3. 4.1.3. StoreProvider
      4. 4.1.4. StoreConnector
      5. 4.1.5. StoreBuilder
      6. 4.1.6. Redux包下提供的工具方法
    2. 4.2. 路由管理
      1. 4.2.1. 引入
      2. 4.2.2. 使用
    3. 4.3. 国际化
      1. 4.3.1. 导入flutter_localization包
      2. 4.3.2. 引入
      3. 4.3.3. 使用Flutter-i18n插件
      4. 4.3.4. 声明资源
      5. 4.3.5. 使用资源
  5. 5. 插件的使用
    1. 5.1. camera 0.5.7+2
      1. 5.1.1. 引入
      2. 5.1.2. iOS权限
      3. 5.1.3. 获取Camera
      4. 5.1.4. 使用
  6. 6. Widget使用
    1. 6.1. ClipPath
    2. 6.2. 简单封装
      1. 6.2.1. Dio简单封装
      2. 6.2.2. FutureBuilder与网络请求