Flutter 总结

// private static final String DEFAULT_MAVEN_HOST = "https://storage.googleapis.com";
  private static final String DEFAULT_MAVEN_HOST = "https://storage.flutter-io.cn/download.flutter.io";

# 查看包的依赖关系
flutter pub deps
# 更新包版本 获取pubspec.yaml文件中列出的所有依赖包的最新版本
flutter packages upgrade
# 获取pubspec.yaml文件中列出的所有依赖包
flutter packages get
# 打包脚本工具
flutter_distributor  release --name dev
flutter以module的方式引入，pod install 之前需要在example目录下用flutter build ios --release 编译一次
然后进入下一级的ios目录执行，pod install

# 打包
1.flutter clean
2.flutter pub get
3.flutter build apk --target-platform android-arm,android-arm64  --no-shrink

flutter module 集成进原生项目
// 创建module
flutter create --template module xxxName
//执行
flutter build ios --release 
flutter build ios-framework // 选项 B 在 Xcode 中集成 frameworks 生成 xx
flutter create . 创建配置文件

import 'package:flutter/cupertino.dart';
ios设计风格

class MyHomePage extends StatefulWidget {
  MyHomePage({@required Key key, this.title}) : super(key: key);
}
注意：参数为大括号，默认可选，@required注解为必填。

import 'dart:async' show Future;
import 'package:flutter/services.dart' show rootBundle;
Future<String> loadAsset() async {
	return await rootBundle.loadString('my-assets/data.json');
}

class Strings{
	static String welcomeMessage = "Welcome To Flutter";
}
使用
import 'package:flutter_localizations/flutter_localizations.dart';
Text(Strings.welcomeMessage);

/*
* 为什么flutter在设计的时候StatefulWidget的build方法放在State中
* 1. build出来的Widget是需要依赖State中的变量（状态/数据)
* 2. 在Flutter的运行过程中：
*     Widget是不断地额销毁和创建的
*     当我们自己的状态发生改变时，并不希望重新创建一个新的State
* */

class JLContentBody extends StatefulWidget{

  @override
  State<StatefulWidget> createState() {
    return JLContentBodyState();
  }

}
class JLContentBodyState extends State<JLContentBody>{

  var flag = true;

  @override
  Widget build(BuildContext context) {
    return Center(
      child: Row(
        mainAxisAlignment: MainAxisAlignment.center,//主轴
        children: <Widget>[
          Checkbox(
              value: flag,
              onChanged: (value){
                setState(() {
                  flag = value;
                });
                print(flag);
              }),
          Text("同意协议")
        ],

      ),
    );
  }
}

class _JLHomeContentState extends State<JLHomeContent> {
  int _counter = 0;// 内部状态

  @override
  Widget build(BuildContext context) {
    return Center(
      child: Column(
        mainAxisAlignment: MainAxisAlignment.center,//主轴居中
        children: <Widget>[
          _getButtons(),
          Text("当前计数:$_counter",style: TextStyle(fontSize: 25),),
          Text("传过来的信息:${widget.message}",)
        ],
      ),
    );
  }

  Widget _getButtons(){
    return Row(
      mainAxisAlignment: MainAxisAlignment.center,
      children: <Widget>[
        RaisedButton(
            child: Text("+", style: TextStyle(fontSize: 20, color: Colors.white),),
            color: Colors.red,
            onPressed: (){
              setState(() {
//                相当于匿名函数，这里，外边设置++也可以
                _counter ++;
              });
            }),
      ],
    );
  }
}

class JLHomePage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text( "商品列表"),
      ),
      body: JLHomeContent("haha"),
    );
  }
}

//Widget 不加下划线，一般暴露给外部使用。
//State 是加下划线，状态类，只给Widget内部使用
class JLHomeContent extends StatefulWidget {
  final String message;
  JLHomeContent(this.message);

  @override
  _JLHomeContentState createState() => _JLHomeContentState();
}

class _JLHomeContentState extends State<JLHomeContent> {
  int _counter = 0;

  @override
  Widget build(BuildContext context) {
    return Center(
      child: Column(
        mainAxisAlignment: MainAxisAlignment.center,//主轴居中
        children: <Widget>[
          _getButtons(),
          Text("当前计数:$_counter",style: TextStyle(fontSize: 25),),
          Text("传过来的信息:${widget.message}",)// 使用外部的状态
        ],
      ),
    );
  }
}

@override
Widget build(BuildContext context){
	return Colum(
		mainAxisAlignment:MainAxisAlignment.center,
		children: <Widget>[
			Text(Column one),
			Text(Column two),
		],
	);
}

1. Stateful Widget
Constructor -> Widget_createState()
2. State_object
Constructor -> mounted -> initState -> dirty state ->build -> clean state -> dispose
															↓						↑			↑									↓
																					   		↑	setState			 ←↓
											didChangeDependencies			↑didUpdateWidget ←↓

class JLHomeContent extends StatefulWidget {
  JLHomeContent(){
    print("1.调用JLHomeContent的constructor");
  }
  @override
  _JLHomeContentState createState() {
    print("2.调用JLHomeContent的createState方法");
    return _JLHomeContentState();
  }
}

class _JLHomeContentState extends State<JLHomeContent> {
  _JLHomeContentState(){
    print("3.调用_JLHomeContentState的constructor方法");
  }
  @override
  void initState() {
    print("4. 调用State的initState方法");
    // 这里必须调super
    super.initState();

  }
  @override
  Widget build(BuildContext context) {
    print("5. 调用build ");
    return Text("data");
  }

  @override
  void dispose() {
    print("6.调用State的dispose方法");
    super.dispose();
  }
}

body: ListView.builder(
	itemCount: widgets.length,
	itemBuilder: (BuilderContext context,int position){
		return getRow(position)
	}
)

Widget getRow(int i){
	return GestureDetector(
		child: Padding(
			padding: EdgeInsets.all(10.0),
			child: Text("Row $i"),
		),
		onTap: (){
			setState((){
        // 当点击时 动态添加一个元素，而不是创建一个list。高明的地方
       // 不会导致整个列表被渲染，只会渲染部分，所以效率比较高。 
				widgets.add(getRow(widgets.length+1));
				print('row $i');
			});
		},
	);
}