Flutter热敏打印机控制插件thermal_printer的使用

thermal_printer 是一个用于发现打印机并发送打印命令的库。它支持多种平台（如Android、iOS和Windows）以及不同的接口（如蓝牙、BLE、USB和WiFi/以太网）。本文将介绍如何在Flutter项目中使用该插件。

主要特性

• 支持Android、iOS和Windows平台
• 扫描蓝牙设备
• 发送原始的 List<int> bytes 数据到设备

平台支持矩阵

如何使用

初始化PrinterManager实例

首先，需要初始化 PrinterManager 实例：

import 'package:thermal_printer/thermal_printer.dart';

var printerManager = PrinterManager.instance;

扫描设备

根据打印机类型（如蓝牙、USB或网络），可以调用 discovery 方法来扫描设备：

var devices = [];
_scan(PrinterType type, {bool isBle = false}) {
  // 查找打印机
  PrinterManager.instance.discovery(type: type, isBle: isBle).listen((device) {
    devices.add(device);
  });
}

连接设备

选择合适的打印机类型，并连接到选定的设备：

_connectDevice(PrinterDevice selectedPrinter, PrinterType type, {bool reconnect = false, bool isBle = false, String? ipAddress = null}) async {
  switch (type) {
    case PrinterType.usb:
      await PrinterManager.instance.connect(
          type: type,
          model: UsbPrinterInput(name: selectedPrinter.name, productId: selectedPrinter.productId, vendorId: selectedPrinter.vendorId));
      break;
    case PrinterType.bluetooth:
      await PrinterManager.instance.connect(
          type: type,
          model: BluetoothPrinterInput(
              name: selectedPrinter.name,
              address: selectedPrinter.address!,
              isBle: isBle,
              autoConnect: reconnect));
      break;
    case PrinterType.network:
      await PrinterManager.instance.connect(type: type, model: TcpPrinterInput(ipAddress: ipAddress ?? selectedPrinter.address!));
      break;
    default:
  }
}

断开连接

断开当前连接的设备：

_disconnectDevice(PrinterType type) async {
  await PrinterManager.instance.disconnect(type: type);
}

监听蓝牙状态变化

监听蓝牙设备的状态变化：

PrinterManager.instance.stateBluetooth.listen((status) {
  log(' ----------------- status bt $status ------------------ ');
});

发送字节数据进行打印

生成要打印的数据，并通过 send 方法发送给打印机：

_sendBytesToPrint(List<int> bytes, PrinterType type) async { 
  PrinterManager.instance.send(type: type, bytes: bytes);
}

示例Demo

以下是一个完整的示例代码，展示了如何使用 thermal_printer 插件：

import 'dart:async';
import 'dart:io';
import 'package:flutter/material.dart';
import 'package:thermal_printer/thermal_printer.dart';

void main() => runApp(MyApp());

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  var defaultPrinterType = PrinterType.bluetooth;
  var _isConnected = false;
  var printerManager = PrinterManager.instance;
  var devices = <PrinterDevice>[];
  StreamSubscription<PrinterDevice>? _subscription;

  @override
  void initState() {
    super.initState();
    _scan();
  }

  void _scan() {
    devices.clear();
    _subscription = printerManager.discovery(type: defaultPrinterType).listen((device) {
      devices.add(device);
      setState(() {});
    });
  }

  void _connectDevice(PrinterDevice device) async {
    await printerManager.connect(
        type: defaultPrinterType,
        model: BluetoothPrinterInput(name: device.name, address: device.address!));
    setState(() {
      _isConnected = true;
    });
  }

  void _disconnectDevice() async {
    await printerManager.disconnect(type: defaultPrinterType);
    setState(() {
      _isConnected = false;
    });
  }

  void _printTestTicket() async {
    final profile = await CapabilityProfile.load();
    final generator = Generator(PaperSize.mm58, profile);
    List<int> bytes = [];

    bytes += generator.text('Test Print', styles: const PosStyles(align: PosAlign.center));
    bytes += generator.text('Product 1');
    bytes += generator.text('Product 2');

    printerManager.send(type: defaultPrinterType, bytes: bytes);
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(title: const Text('Thermal Printer Demo')),
        body: Center(
          child: Column(
            children: [
              ElevatedButton(
                onPressed: !_isConnected ? () => _connectDevice(devices.first) : null,
                child: const Text("Connect"),
              ),
              ElevatedButton(
                onPressed: _isConnected ? _disconnectDevice : null,
                child: const Text("Disconnect"),
              ),
              ElevatedButton(
                onPressed: _isConnected ? _printTestTicket : null,
                child: const Text("Print Test Ticket"),
              ),
              Expanded(
                child: ListView.builder(
                  itemCount: devices.length,
                  itemBuilder: (context, index) {
                    final device = devices[index];
                    return ListTile(
                      title: Text(device.name),
                      subtitle: Text(device.address!),
                      onTap: () => _connectDevice(device),
                    );
                  },
                ),
              ),
            ],
          ),
        ),
      ),
    );
  }
}

此示例展示了如何扫描、连接、断开连接和打印测试票。你可以根据自己的需求修改和扩展这个示例。