如何在焦点上更改Flutter TextField边框颜色？

import 'package:flutter/material.dart';

TextField(
  decoration: InputDecoration(
    border: OutlineInputBorder(
      borderSide: BorderSide(color: Colors.red), // 设置边框颜色
    ),
  ),
)

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('Change TextField Border Color'),
        ),
        body: Center(
          child: Padding(
            padding: EdgeInsets.all(20.0),
            child: TextField(
              decoration: InputDecoration(
                border: OutlineInputBorder(
                  borderSide: BorderSide(color: Colors.red), // 设置边框颜色
                ),
              ),
            ),
          ),
        ),
      ),
    );
  }
}