我假设你要自定义的日期选择器 不同 ，从你的主旋律。通常，日期选择器遵循您的主题。

如果是这样，请将触发操作的按钮包装在的Builder内部Theme。例如，这是一个FAB，它会弹出一个橙色的日期选择器（在轻材料应用程序主题中），并从主主题继承其余部分。

  floatingActionButton: new Theme(
    data: Theme.of(context).copyWith(
          primaryColor: Colors.amber,
        ),
    child: new Builder(
      builder: (context) => new FloatingActionButton(
            child: new Icon(Icons.date_range),
            onPressed: () => showDatePicker(
                  context: context,
                  initialDate: new DateTime.now(),
                  firstDate:
                      new DateTime.now().subtract(new Duration(days: 30)),
                  lastDate: new DateTime.now().add(new Duration(days: 30)),
                ),
          ),
    ),
  ),

检查date_picker.dart的源代码以查看主题的哪些部分会影响日期选择器的不同方面。

如果您只是想让选择器遵循主题，这是一个工作示例

import 'package:flutter/material.dart';

class PickerThemeDemo extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: new AppBar(title: const Text('Picker theme demo')),
      body: new Container(),
      floatingActionButton: new FloatingActionButton(
        child: new Icon(Icons.date_range),
        onPressed: () => showDatePicker(
              context: context,
              initialDate: new DateTime.now(),
              firstDate: new DateTime.now().subtract(new Duration(days: 30)),
              lastDate: new DateTime.now().add(new Duration(days: 30)),
            ),
      ),
    );
  }
}

Color hexToColor(int rgb) => new Color(0xFF000000 + rgb);

class CustomTheme extends Theme {
  //Primary Blue: #335C81 (51, 92, 129)
  //Light Blue:   #74B3CE (116, 179, 206)
  //Yellow:       #FCA311 (252, 163, 17)
  //Red:          #E15554 (255, 85, 84)
  //Green:        #3BB273 (59, 178, 115)

  static Color blueDark = hexToColor(0x335C81);
  static Color blueLight = hexToColor(0x74B3CE);
  static Color yellow = hexToColor(0xFCA311);
  static Color red = hexToColor(0xE15554);
  static Color green = hexToColor(0x3BB273);

  CustomTheme(Widget child)
      : super(
          child: child,
          data: new ThemeData(
            primaryColor: blueDark,
            accentColor: yellow,
            cardColor: blueLight,
            backgroundColor: blueDark,
            highlightColor: red,
            splashColor: green,
          ),
        );
}

void main() {
  runApp(
    new MaterialApp(
      home: new CustomTheme(new PickerThemeDemo()),
    ),
  );
}

如果要将主题应用于整个应用程序，则可以将其最简洁地添加到Material应用程序中（无需CustomTheme类）：

Color hexToColor(int rgb) => new Color(0xFF000000 + rgb);

void main() {
  runApp(
    new MaterialApp(
      theme: new ThemeData(
        brightness: Brightness.light,
        primaryColor: hexToColor(0x335C81),
        accentColor: hexToColor(0xFCA311),
        splashColor: hexToColor(0x3BB273),
      ),
      home: new PickerThemeDemo(),
    ),
  );
}