如何在flutter中显示工具栏操作的批次计数？

import 'package:flutter/material.dart';

class BatchCountManager extends StatefulWidget {
  @override
  _BatchCountManagerState createState() => _BatchCountManagerState();
}

class _BatchCountManagerState extends State<BatchCountManager> {
  int _batchCount = 0;

  void _incrementBatchCount() {
    setState(() {
      _batchCount++;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Batch Count Example'),
      ),
      body: Center(
        child: Text(
          'Batch Count: $_batchCount',
          style: TextStyle(fontSize: 24),
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementBatchCount,
        child: Icon(Icons.add),
      ),
    );
  }
}

void main() {
  runApp(MaterialApp(
    home: BatchCountManager(),
  ));
}