Flutter安卓USB打印机插件yjy_android_usb_printer的使用

Flutter安卓USB打印机插件yjy_android_usb_printer的使用

flutter plugin

android_usb_printer

flutter android 端插件，提供操作 usb 打印机方法能力

使用方法

1. 在pubspec.yaml文件中添加依赖：

   dependencies:
     android_usb_printer: ^0.0.1

2. 初始化并查询本地打印机设备：

   import 'package:flutter/services.dart';
   import 'package:yjy_android_usb_printer/android_usb_printer.dart';
   
   void main() {
     runApp(const MyApp());
   }
   
   class MyApp extends StatefulWidget {
     const MyApp({super.key});
   
     [@override](/user/override)
     State<MyApp> createState() => _MyAppState();
   }
   
   class _MyAppState extends State<MyApp> {
     String _platformVersion = 'Unknown';
     final _androidUsbPrinterPlugin = AndroidUsbPrinterPlatform.instance;
   
     [@override](/user/override)
     void initState() {
       super.initState();
       initPlatformState();
     }
   
     // 查询本地打印机设备
     Future<void> initPlatformState() async {
       String platformVersion;
       try {
         platformVersion = await _androidUsbPrinterPlugin
             .queryLocalUsbDevice()
             .then((value) => value.map((e) => e.toMap()).toList().toString()) ??
             'Unknown platform version';
       } on PlatformException {
         platformVersion = 'Failed to get platform version.';
       }
   
       if (!mounted) return;
   
       setState(() {
         _platformVersion = platformVersion;
       });
     }
   
     [@override](/user/override)
     Widget build(BuildContext context) {
       return MaterialApp(
         home: Scaffold(
           appBar: AppBar(
             title: const Text('Plugin example app'),
           ),
           body: Center(
             child: Text('Running on: $_platformVersion\n'),
           ),
         ),
       );
     }
   }

3. 打印字节数组：

   // 假设已获取到打印机设备信息和要打印的数据
   final usbDeviceInfo = UsbDeviceInfo(vendorId: 1234, productId: 5678, serialNumber: 'serial123');
   final bytesToPrint = [/* 要打印的数据 */];
   
   // 发送打印字节数组
   _androidUsbPrinterPlugin.writeBytes(usbDeviceInfo, bytesToPrint);

提供API方法

以下是插件提供的API方法及详细说明：

/// 获取本地打印机列表
Future<List<UsbDeviceInfo>> queryLocalUsbDevice()

/// 打印机发送字节数据
/// @param singleLimit, 单次最大传输字节长度，内部会将 bytes 按照 singleLimit 阈值进行切割分组后依次 write
Future<int> writeBytes(UsbDeviceInfo usbDeviceInfo, List<int> bytes, {int singleLimit = -1})

/// 接收打印机字节数据
/// @param timeOut, timeOut毫秒内无接收数据直接返回null
Future<Uint8List?> readBytes(UsbDeviceInfo usbDeviceInfo, {int timeOut = 2000})

/// 获取打印机连接状态
Future<bool> checkDeviceConn(UsbDeviceInfo usbDeviceInfo)

/// 打印机连接
Future<bool> connect(UsbDeviceInfo usbDeviceInfo)

/// 打印机断开连接
Future<bool> disconnect(UsbDeviceInfo usbDeviceInfo)

/// 获取打印机设备权限
Future<bool> checkDevicePermission(UsbDeviceInfo usbDeviceInfo)

/// 申请打印机设备权限
Future<bool> requestDevicePermission(UsbDeviceInfo usbDeviceInfo)

/// 删除原生层中 usb conn 缓存（删除设备时可调用）
Future<dynamic> removeUsbConnCache(UsbDeviceInfo usbDeviceInfo)

提供监听 USB 插拔，USB 设备授权能力

可以通过监听 USB 插拔事件和设备授权状态来动态管理设备连接：

// 监听 USB 插拔，USB 设备授权
AndroidUsbPrinterPlatform.instance.usbPlugInfoStream.listen((usbPlugInfo) {
  final usbDeviceInfo = usbPlugInfo.usbDevice; // 插入的 USB 设备信息（vId, pId, sId）
  final plug = usbPlugInfo.plug; // 消息类型枚举（包含状态：拔出、插入、授权成功）
});

UsbPlugInfo 结构如下：

class UsbPlugInfo {
  final UsbPlugInfoEnum plug;
  final UsbDeviceInfo usbDevice;

  UsbPlugInfo(this.usbDevice, this.plug);
}

enum UsbPlugInfoEnum {
  attached, // 插入
  detached, // 拔出
  granted, // 授权成功
}

完整示例代码

以下是完整的示例代码，展示如何初始化、查询设备并打印数据：

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

import 'package:flutter/services.dart';
import 'package:yjy_android_usb_printer/android_usb_printer.dart';

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

class MyApp extends StatefulWidget {
  const MyApp({super.key});

  [@override](/user/override)
  State<MyApp> createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  String _platformVersion = 'Unknown';
  final _androidUsbPrinterPlugin = AndroidUsbPrinterPlatform.instance;

  [@override](/user/override)
  void initState() {
    super.initState();
    initPlatformState();
  }

  // 查询本地打印机设备
  Future<void> initPlatformState() async {
    String platformVersion;
    try {
      final devices = await _androidUsbPrinterPlugin.queryLocalUsbDevice();
      platformVersion = devices.map((e) => e.toMap()).toList().toString();
    } on PlatformException {
      platformVersion = 'Failed to get platform version.';
    }

    if (!mounted) return;

    setState(() {
      _platformVersion = platformVersion;
    });
  }

  [@override](/user/override)
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: const Text('USB Printer Example'),
        ),
        body: Center(
          child: Column(
            mainAxisAlignment: MainAxisAlignment.center,
            children: [
            Text('Running on: $_platformVersion\n'),
            ElevatedButton(
              onPressed: () async {
                // 假设已获取到打印机设备信息和要打印的数据
                final usbDeviceInfo = UsbDeviceInfo(vendorId: 1234, productId: 5678, serialNumber: 'serial123');
                final bytesToPrint = [/* 要打印的数据 */];
                await _androidUsbPrinterPlugin.writeBytes(usbDeviceInfo, bytesToPrint);
              },
              child: Text('Print Data'),
            ),
          ],
        ),
      ),
    );
  }
}