如何将CircularProgressIndicator添加到Firebase登录？

dependencies:
  firebase_auth: ^版本号

import 'package:flutter/material.dart';
import 'package:firebase_auth/firebase_auth.dart';

class LoginPage extends StatefulWidget {
  @override
  _LoginPageState createState() => _LoginPageState();
}

class _LoginPageState extends State<LoginPage> {
  final FirebaseAuth _auth = FirebaseAuth.instance;
  bool _isLoading = false;

  void _login() async {
    setState(() {
      _isLoading = true;
    });

    // 进行Firebase登录逻辑
    try {
      await _auth.signInWithEmailAndPassword(
        email: 'your_email',
        password: 'your_password',
      );
      // 登录成功后的处理逻辑
    } catch (e) {
      // 处理登录错误
    }

    setState(() {
      _isLoading = false;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('登录页面'),
      ),
      body: Center(
        child: _isLoading
            ? CircularProgressIndicator()  // 显示CircularProgressIndicator
            : RaisedButton(
                child: Text('登录'),
                onPressed: _login,
              ),
      ),
    );
  }
}