Android OTG U盘相关

不念不忘少年蓝@ 2022-11-20 08:20 200阅读 0赞

## 三方库 ##

`implementation 'me.jahnen:libaums:0.7.6'`

## 权限 ##

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
    
     <uses-feature android:name="android.hardware.usb.host" />

**Note**:Android 10 需要在Application标签中添加一条 `android:requestLegacyExternalStorage="true"` ,用于使用遗留存储权限，据说是因为安全原因。

## 帮助类 ##

这里主要是用于读写图片的，如果只写文件就更简单了

/**
     * created by Taoyuan on 2020/10/26
     * USB帮助类
     */
    public class UsbUtils {
        
        private Context context;
    
        private UsbMassStorageDevice mDevice;
        private UsbFile cFolder;
    
        private static final String ACTION_USB_PERMISSION = "com.android.example.USB_PERMISSION";
        // 文件目录
        public static String appDir = "App";
        public static String picDir = "picture";
    
        public boolean mUSBisOK = false;
    
        public UsbUtils(Context context) {
        
            this.context = context;
            init();
        }
    
        /**
         * 初始化广播，用于监听权限和插拔USB
         */
        private void init() {
        
            // 权限广播
            BroadcastReceiver mUsbPermissionActionReceiver = new BroadcastReceiver() {
        
                public void onReceive(Context context, Intent intent) {
        
                    String action = intent.getAction();
                    if (ACTION_USB_PERMISSION.equals(action)) {
        
                        context.unregisterReceiver(this);//解注册
                        synchronized (this) {
        
                            UsbDevice usbDevice = intent.getParcelableExtra(UsbManager.EXTRA_DEVICE);
                            if (intent.getBooleanExtra(UsbManager.EXTRA_PERMISSION_GRANTED, false)) {
        
                                if (usbDevice != null) {
        
                                    L.e(usbDevice.getDeviceName() + "已获取USB权限");
                                    //接收到U盘插入广播，尝试读取U盘设备数据
                                    mUSBisOK = readUsbList();//U盘已插入,并获取权限
                                }
                            } else {
        
                                L.e("USB权限已被拒绝，Permission denied for device" + usbDevice);
                            }
                        }
    
                    }
                }
            };
    
            context.registerReceiver(mUsbPermissionActionReceiver, new IntentFilter(ACTION_USB_PERMISSION));
    
            // otg插拔广播
            BroadcastReceiver mOtgReceiver = new BroadcastReceiver() {
        
                @Override
                public void onReceive(Context context, Intent intent) {
        
                    if (intent.getAction() == null) return;
                    switch (intent.getAction()) {
        
                        case UsbManager.ACTION_USB_DEVICE_ATTACHED://接收到U盘设备插入广播
                            T.show(context, "U盘已插入");
                            UsbDevice device_add = intent.getParcelableExtra(UsbManager.EXTRA_DEVICE);
                            if (device_add != null) {
        
                                //接收到U盘插入广播，尝试读取U盘设备数据
                                mUSBisOK = readUsbList();//U盘已插入
                            }
                            break;
                        case UsbManager.ACTION_USB_DEVICE_DETACHED://接收到U盘设设备拔出广播
                            T.show(context, "U盘已拔出");
                            mUSBisOK = readUsbList();//U盘已拔出
                            break;
                    }
                }
            };
    
            //监听otg插入 拔出
            IntentFilter usbDeviceStateFilter = new IntentFilter();
            usbDeviceStateFilter.addAction(UsbManager.ACTION_USB_DEVICE_ATTACHED);
            usbDeviceStateFilter.addAction(UsbManager.ACTION_USB_DEVICE_DETACHED);
            context.registerReceiver(mOtgReceiver, usbDeviceStateFilter);
        }
    
    
        /**
         * 读取U盘列表
         *
         * @return 是否读取成功
         */
        public boolean readUsbList() {
        
            boolean isOK = false;
            //设备管理器
            UsbManager usbManager = (UsbManager) context.getSystemService(Context.USB_SERVICE);
            //获取U盘存储设备
            UsbMassStorageDevice[] storageDevices = UsbMassStorageDevice.getMassStorageDevices(context);
            PendingIntent pendingIntent = PendingIntent.getBroadcast(context, 0, new Intent(ACTION_USB_PERMISSION), 0);
            //一般手机只有1个OTG插口
            for (UsbMassStorageDevice device : storageDevices) {
        
                //读取设备是否有权限
                if (usbManager == null) return false;
                if (usbManager.hasPermission(device.getUsbDevice())) {
        
                    isOK = readDevice(device);
                } else {
        
                    //没有权限，进行申请
                    usbManager.requestPermission(device.getUsbDevice(), pendingIntent);
                }
            }
            if (storageDevices.length == 0) {
        
                T.show(context, "请插入可用的U盘");
            }
            return isOK;
        }
    
        /**
         * 读取设备(需已申请权限)
         *
         * @param device usb设备
         * @return 是否读取成功
         */
        private boolean readDevice(UsbMassStorageDevice device) {
        
            try {
        
                mDevice = device;
                mDevice.init();
    
                // 一般U盘只有一个分区，在android 10 实测时，只有FAT32可以被读取
                if (mDevice.getPartitions().size() == 0) {
        
                    T.show(context, "读取设备分区失败");
                    return false;
                } else {
        
                    T.show(context, "U盘已就绪");
                    FileSystem currentFs = mDevice.getPartitions().get(0).getFileSystem();
                    cFolder = currentFs.getRootDirectory();
                    return true;
                }
            } catch (IOException e) {
        
                e.printStackTrace();
            }
            return false;
        }
    
    
        /**
         * 向USB写数据
         *
         * @param fileList 需要写入的文件
         * @return 是否写入成功
         */
        public boolean write(List<File> fileList) {
        
            try {
        
                // 获取usb图片目录
                UsbFile[] usbFiles = cFolder.listFiles();
                UsbFile applicationDir = null;
                UsbFile pictureDir = null;
                // 判断目录是否存在，不存在则创建
                for (UsbFile usbFile : usbFiles) {
        
                    if (usbFile.getName().equals(appDir)) {
        
                        applicationDir = usbFile;
                    }
                }
                // app目录不存在则创建
                if (applicationDir == null) {
        
                    applicationDir = cFolder.createDirectory(appDir);
                } else {
        
                    // 存在则遍历pic目录
                    for (UsbFile usbFile : applicationDir.listFiles()) {
        
                        if (usbFile.getName().equals(picDir)) {
        
                            pictureDir = usbFile;
                        }
                    }
                }
                if (pictureDir == null) {
        
                    pictureDir = applicationDir.createDirectory(picDir);
                }
    
                // 如果不存在则直接创建
                if (pictureDir.listFiles().length > 0) {
        
                    // 如果存在，则先把重复文件从列表中清空一遍
                    for (UsbFile usbFile : pictureDir.listFiles()) {
        
                        for (int i = fileList.size() - 1; i >= 0; i--) {
        
                            if (fileList.get(i).getName().equals(usbFile.getName())) {
        
                                fileList.remove(i);
                            }
                        }
                    }
                }
    
                if (fileList.size() == 0) {
        
                    T.show(context, "选择文件已全部导出");
                    return false;
                }
                List<UsbFile> usbFileList = new ArrayList<>();
                for (File file : fileList) {
        
                    UsbFile file1 = pictureDir.createFile(file.getName());
                    usbFileList.add(file1);
                }
    
                for (UsbFile usbFile : usbFileList) {
        
                    for (int i = 0; i < fileList.size(); i++) {
        
                        if (fileList.get(i).getName().equals(usbFile.getName())) {
        
                            write2USB(fileList.get(i).getAbsolutePath(), usbFile);
                        }
                    }
                }
                mDevice.close();
                return true;
            } catch (IOException e) {
        
                e.printStackTrace();
            }
            return false;
        }
    
    
        /**
         * 写文件
         *
         * @param source android设备中的文件路径
         * @param target usb目标文件
         */
        public void write2USB(String source, UsbFile target) {
        
            try {
        
                BufferedInputStream bis = new BufferedInputStream(new FileInputStream(source));
                UsbFileOutputStream usbos = new UsbFileOutputStream(target);
    
                byte[] buffer = new byte[1024];
                int len = -1;
                while ((len = bis.read(buffer)) != -1) {
        
                    usbos.write(buffer, 0, len);
                }
                bis.close();
                usbos.flush();
                usbos.close();
            } catch (java.io.FileNotFoundException e) {
        
                L.e("The File doesn't not exist.");
            } catch (IOException e) {
        
                e.printStackTrace();
            }
    
        }
    
    
    }

## 使用 ##

UsbUtils usbUtils = new UsbUtils(this);
    // 加载U盘
    usbUtils.mUSBisOK = usbUtils.readUsbList();
    
    // 使用动态目录
    if (!usbUtils.mUSBisOK) {
        
        T.show(this, "请先加载U盘");
        return;
    }
    UsbUtils.picDir = text;
    
    // 写文件
    if (usbUtils.mUSBisOK) {
        
        List<File> fileList = new ArrayList<>();
        for (String imgPath : mData) {
        
       		File file = FileUtils.getFileByPath(imgPath);
            if (file.exists()) fileList.add(file);
        }
        boolean writeOK = usbUtils.write(fileList);
        if (writeOK) T.show(
                this,
                "导出成功：" + UsbUtils.appDir + "/" + UsbUtils.picDir,
                true);
    }