如何在flutter中设置填充材料设计风格forTextFormField？

import 'package:flutter/material.dart';

TextFormField(
  decoration: InputDecoration(
    filled: true,  // 设置为true，表示使用填充材料设计风格
    fillColor: Colors.grey[200],  // 设置填充颜色
    hintText: '请输入内容',  // 设置提示文本
    border: OutlineInputBorder(  // 设置边框样式
      borderRadius: BorderRadius.circular(10.0),  // 设置边框圆角
      borderSide: BorderSide.none,  // 设置边框样式为无
    ),
  ),
),

import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: Text('Flutter TextFormField'),
        ),
        body: Center(
          child: Padding(
            padding: EdgeInsets.all(20.0),
            child: TextFormField(
              decoration: InputDecoration(
                filled: true,
                fillColor: Colors.grey[200],
                hintText: '请输入内容',
                border: OutlineInputBorder(
                  borderRadius: BorderRadius.circular(10.0),
                  borderSide: BorderSide.none,
                ),
              ),
            ),
          ),
        ),
      ),
    );
  }
}