• 主入口适配普通theme和黑暗theme

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: CYPublicTheme.lightTheme,
      darkTheme: CYPublicTheme.darkTheme,
      home:APPHomePage(),
    );
  }
}

• 封装好的主题类文件
  theme/theme.dart

import 'package:flutter/material.dart';

class CYPublicTheme{
  static const double normalFontSize = 15;
  static const double titleFontSize = 20;
  static const double subTitleFontSize = 18;

  static final Color lightThemeTextColor = Colors.black;
  static final Color darkThemeTextColor = Colors.white;

  static final Color cardColorLight = Colors.white;
  static final Color cardColorDark = Colors.blueGrey;




  // primarySwatch包含了 primaryColor 和 accentColor（primaryColor和accentColor也可以单独设置）
  // primarySwatch实际传入的是MaterialColor，不是一个简单的color
  static final ThemeData lightTheme = ThemeData(
    splashColor: Colors.transparent,
    visualDensity: VisualDensity.adaptivePlatformDensity,
    highlightColor: Colors.transparent,//去除点击tabbar的过度效果
    // brightness: Brightness.light,//亮度，明亮模式
    primarySwatch: Colors.red,
    // primaryColor: Colors.red,//主要决定导航和底部bottombar颜色
    //   accentColor: Colors.blue,//button和switch等颜色
    textTheme: TextTheme(
      bodyText1:TextStyle(fontSize: normalFontSize,color: lightThemeTextColor),// material默认
      //可以通过Theme.of(context).textTheme.bodyText2获取
      // bodyText2:
      // headline1:
      // headline2:
    ),
    buttonTheme: ButtonThemeData(
        height: 25,
        minWidth: 10
    ),
    cardTheme: CardTheme(
      color: cardColorLight,
      elevation: 20
    )
  );

  static final ThemeData darkTheme = ThemeData(
    splashColor: Colors.transparent,
    visualDensity: VisualDensity.adaptivePlatformDensity,
    highlightColor: Colors.transparent,//去除点击tabbar的过度效果
    // brightness: Brightness.dark,//亮度，暗黑模式（）
    primarySwatch: Colors.blueGrey,
    // primaryColor: Colors.blueGrey,//主要决定导航和底部bottombar颜色
    // accentColor: Colors.blue,//button和switch等颜色
    textTheme: TextTheme(
      bodyText1: TextStyle(fontSize: normalFontSize,color: darkThemeTextColor)
      //可以通过Theme.of(context).textTheme.bodyText2获取
      // bodyText2:
      // headline1:
      // headline2:
    ),
    buttonTheme: ButtonThemeData(
      height: 25,
      minWidth: 10
    ),
    cardTheme: CardTheme(
      color: cardColorDark,
      elevation: 20
    )
  );
}

• 其他子widget如果完全不像使用全局的主题可以：

return Scaffold(
      backgroundColor: Colors.black,
      body: Theme(
        data: ThemeData(
          primaryColor: Colors.red
        ),
        child: Center(),
      )
);

• 其他子widget如果想复写主题可以：

return Scaffold(
      backgroundColor: Colors.black,
      body: Theme(
        data: Theme.of(context).copyWith(
          primaryColor: Colors.purple
        ),
        child: Center(),
      )
);