flutter学习（状态组件，组件）

dart的库地址： https://pub.dev/

从零开始的todolist： https://blog.csdn.net/hsoldier/article/details/110756734

从零开始的组件使用   https://www.jianshu.com/p/101d943f71fc?utm_campaign=maleskine&utm_content=note&utm_medium=seo_notes&utm_source=recommendation

有状态组件 StatefulWidget

class TapboxA extends StatefulWidget {
  TapboxA({Key key}) : super(key: key);

  @override
  _TapboxAState createState() => new _TapboxAState();
}

class _TapboxAState extends State<TapboxA> {
  bool _active = false;

  void _handleTap() {
    setState(() {
      _active = !_active;
    });
  }

  Widget build(BuildContext context) {
    return new GestureDetector(
      onTap: _handleTap,
      child: new Container(
        child: new Center(
          child: new Text(
            _active ? 'Active' : 'Inactive',
            style: new TextStyle(fontSize: 32.0, color: Colors.white),
          ),
        ),
         200.0,
        height: 200.0,
        decoration: new BoxDecoration(
          color: _active ? Colors.lightGreen[700] : Colors.grey[600],
        ),
      ),
    );
  }
}

无状态组件StatelesWidget

class Statesss extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: new AppBar(
        title: new Text("Flutter进阶之旅"),
      ),
      body: ParentWidget(),
    );
  }
}

父元素向下传递方法改变自身状态

import 'package:flutter/material.dart';
/*
 * 通过父传子将方法传下去，点击时触发回调函数，改变父元素的状态
 * */
class ParentWidget extends StatefulWidget {
  @override
  _ParentWidgetState createState() => new _ParentWidgetState();
}

class _ParentWidgetState extends State<ParentWidget> {
  bool _active = false;

  void _handleTapboxChanged(bool newValue) {
    setState(() {
      _active = newValue;
    });
  }

  @override
  Widget build(BuildContext context) {
    return new Container(
      child: new TapboxB(
        active: _active,
        onChanged: _handleTapboxChanged,
      ),
    );
  }
}


class TapboxB extends StatelessWidget {
  TapboxB({Key key, this.active: false, @required this.onChanged})
      : super(key: key);

  final bool active;
  final ValueChanged<bool> onChanged;

  void _handleTap() {
    onChanged(!active);
  }

  Widget build(BuildContext context) {
    return new GestureDetector(
      onTap: _handleTap,
      child: new Container(
        child: new Center(
          child: new Text(
            active ? 'Active' : 'Inactive',
            style: new TextStyle(fontSize: 32.0, color: Colors.white),
          ),
        ),
         200.0,
        height: 200.0,
        decoration: new BoxDecoration(
          color: active ? Colors.lightGreen[700] : Colors.grey[600],
        ),
      ),
    );
  }
}

 设置默认文本样式（DefaultTextStyle地下所有文本内容都继承此样式）

DefaultTextStyle(
        //1.设置文本默认样式
        style: TextStyle(
          color:Colors.red,
          fontSize: 20.0,
        ),
        textAlign: TextAlign.start,
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: <Widget>[
            Text("hello world"),
            Text("I am Jack"),
            Text("I am Jack",
              style: TextStyle(
                  inherit: false, //2.不继承默认样式
                  color: Colors.grey
              ),
            ),
          ],
        ),
      )

使用dio请求数据

import 'package:dio/dio.dart';

void getRequest() async{
  Dio dio =  Dio();
  var header = {"Content-Type":"application/x-www-form-urlencoded"};
  var options = Options(headers:header);
//   地址为（深高速地址，不存在token）
  var url ='http://dd-test.gcnao.cn/gateway/unit/company/getConfig?hostname=http:%2F%2Fdd-test.gcnao.cn&pathname=%2F';
  var response = await dio.get(url,options: options);
  if(response.statusCode == 200){
    var res = response.data;
    print("获取到的数据
$res");
  }else{
    print("失败时获取到的数据
$response.statusCode");
  }

}

 生命周期

打包命令  keytool -genkey -v -keystore C:work_ljxandroid-key/key.jks -keyalg RSA -keysize 2048 -validity 10000 -alias key