flutter_esc_pos_bluetooth 是一个用于在 Flutter 应用中控制蓝牙热敏打印机的插件。它基于 ESC/POS 指令集，允许你通过蓝牙连接打印机并发送打印指令。以下是如何使用 flutter_esc_pos_bluetooth 插件的基本步骤。

1. 添加依赖

首先，在你的 pubspec.yaml 文件中添加 flutter_esc_pos_bluetooth 依赖：

dependencies:
  flutter:
    sdk: flutter
  flutter_esc_pos_bluetooth: ^0.3.0

然后运行 flutter pub get 来安装依赖。

2. 请求蓝牙权限

在 Android 和 iOS 上，使用蓝牙功能需要相应的权限。确保在 AndroidManifest.xml 和 Info.plist 中添加必要的权限。

AndroidManifest.xml:

<uses-permission android:name="android.permission.BLUETOOTH"/>
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN"/>
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>

Info.plist:

<key>NSBluetoothAlwaysUsageDescription</key>
<string>We need access to Bluetooth to connect to the printer.</string>
<key>NSBluetoothPeripheralUsageDescription</key>
<string>We need access to Bluetooth to connect to the printer.</string>
<key>NSLocationAlwaysUsageDescription</key>
<string>We need access to location to scan for Bluetooth devices.</string>
<key>NSLocationWhenInUseUsageDescription</key>
<string>We need access to location to scan for Bluetooth devices.</string>

3. 扫描并连接蓝牙设备

使用 flutter_esc_pos_bluetooth 插件扫描并连接到蓝牙打印机。

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

class PrinterScreen extends StatefulWidget {
  [@override](/user/override)
  _PrinterScreenState createState() => _PrinterScreenState();
}

class _PrinterScreenState extends State<PrinterScreen> {
  PrinterBluetoothManager printerManager = PrinterBluetoothManager();
  List<PrinterBluetooth> _devices = [];

  [@override](/user/override)
  void initState() {
    super.initState();
    printerManager.scanResults.listen((devices) {
      setState(() {
        _devices = devices;
      });
    });
  }

  void _startScan() {
    printerManager.startScan(Duration(seconds: 4));
  }

  void _connectToDevice(PrinterBluetooth device) async {
    await printerManager.selectPrinter(device);
  }

  [@override](/user/override)
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Bluetooth Printer'),
      ),
      body: Column(
        children: [
          ElevatedButton(
            onPressed: _startScan,
            child: Text('Scan for Devices'),
          ),
          Expanded(
            child: ListView.builder(
              itemCount: _devices.length,
              itemBuilder: (context, index) {
                return ListTile(
                  title: Text(_devices[index].name),
                  subtitle: Text(_devices[index].address),
                  onTap: () => _connectToDevice(_devices[index]),
                );
              },
            ),
          ),
        ],
      ),
    );
  }

  [@override](/user/override)
  void dispose() {
    printerManager.stopScan();
    super.dispose();
  }
}

4. 打印内容

连接成功后，你可以使用 PrinterBluetoothManager 发送打印指令。

void _printTestReceipt() async {
  final profile = await CapabilityProfile.load();
  final generator = Generator(PaperSize.mm58, profile);

  List<int> bytes = [];
  bytes += generator.text('Test Receipt');
  bytes += generator.text('----------------');
  bytes += generator.text('Item 1: \$10.00');
  bytes += generator.text('Item 2: \$20.00');
  bytes += generator.text('Total: \$30.00');
  bytes += generator.text('----------------');
  bytes += generator.text('Thank you!');
  bytes += generator.feed(2);
  bytes += generator.cut();

  printerManager.printBytes(bytes);
}

5. 完整示例

将上述代码整合到一个完整的示例中：

import 'package:flutter/material.dart';
import 'package:flutter_esc_pos_bluetooth/flutter_esc_pos_bluetooth.dart';
import 'package:flutter_esc_pos_utils/flutter_esc_pos_utils.dart';

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

class MyApp extends StatelessWidget {
  [@override](/user/override)
  Widget build(BuildContext context) {
    return MaterialApp(
      home: PrinterScreen(),
    );
  }
}

class PrinterScreen extends StatefulWidget {
  [@override](/user/override)
  _PrinterScreenState createState() => _PrinterScreenState();
}

class _PrinterScreenState extends State<PrinterScreen> {
  PrinterBluetoothManager printerManager = PrinterBluetoothManager();
  List<PrinterBluetooth> _devices = [];

  [@override](/user/override)
  void initState() {
    super.initState();
    printerManager.scanResults.listen((devices) {
      setState(() {
        _devices = devices;
      });
    });
  }

  void _startScan() {
    printerManager.startScan(Duration(seconds: 4));
  }

  void _connectToDevice(PrinterBluetooth device) async {
    await printerManager.selectPrinter(device);
  }

  void _printTestReceipt() async {
    final profile = await CapabilityProfile.load();
    final generator = Generator(PaperSize.mm58, profile);

    List<int> bytes = [];
    bytes += generator.text('Test Receipt');
    bytes += generator.text('----------------');
    bytes += generator.text('Item 1: \$10.00');
    bytes += generator.text('Item 2: \$20.00');
    bytes += generator.text('Total: \$30.00');
    bytes += generator.text('----------------');
    bytes += generator.text('Thank you!');
    bytes += generator.feed(2);
    bytes += generator.cut();

    printerManager.printBytes(bytes);
  }

  [@override](/user/override)
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Bluetooth Printer'),
      ),
      body: Column(
        children: [
          ElevatedButton(
            onPressed: _startScan,
            child: Text('Scan for Devices'),
          ),
          Expanded(
            child: ListView.builder(
              itemCount: _devices.length,
              itemBuilder: (context, index) {
                return ListTile(
                  title: Text(_devices[index].name),
                  subtitle: Text(_devices[index].address),
                  onTap: () => _connectToDevice(_devices[index]),
                );
              },
            ),
          ),
          ElevatedButton(
            onPressed: _printTestReceipt,
            child: Text('Print Test Receipt'),
          ),
        ],
      ),
    );
  }

  [@override](/user/override)
  void dispose() {
    printerManager.stopScan();
    super.dispose();
  }
}