准备工作

在build.gradle文件中引用libaums：

compile ‘com.github.mjdev:libaums:+’
在AndroidManifest.xml中添加权限：

android:name=”android.hardware.usb.host”
android:required=”false”/>
android:name=”android.hardware.usb.host”
android:required=”true” />

代码

USBBroadCastReceiver

USBBroadCastReceiver用于监听U盘的插拔，代码如下：

/** * Author ： BlackHao * Time : 2018/5/10 10:07 * Description : USB 广播 * Logs : */public class USBBroadCastReceiver extends BroadcastReceiver {    private UsbListener usbListener;    public static final String ACTION_USB_PERMISSION = "com.android.example.USB_PERMISSION";    @Override    public void onReceive(Context context, Intent intent) {        String action = intent.getAction();        switch (action) {            case ACTION_USB_PERMISSION:                //接受到自定义广播                UsbDevice usbDevice = intent.getParcelableExtra(UsbManager.EXTRA_DEVICE);                if (intent.getBooleanExtra(UsbManager.EXTRA_PERMISSION_GRANTED, false)) {                    //允许权限申请                    if (usbDevice != null) {                        //回调                        if (usbListener != null) {                            usbListener.getReadUsbPermission(usbDevice);                        }                    }                } else {                    if (usbListener != null) {                        usbListener.failedReadUsb(usbDevice);                    }                }                break;            case UsbManager.ACTION_USB_DEVICE_ATTACHED://接收到存储设备插入广播                UsbDevice device_add = intent.getParcelableExtra(UsbManager.EXTRA_DEVICE);                if (device_add != null) {                    if (usbListener != null) {                        usbListener.insertUsb(device_add);                    }                }                break;            case UsbManager.ACTION_USB_DEVICE_DETACHED:                //接收到存储设备拔出广播                UsbDevice device_remove = intent.getParcelableExtra(UsbManager.EXTRA_DEVICE);                if (device_remove != null) {                    if (usbListener != null) {                        usbListener.removeUsb(device_remove);                    }                }                break;        }    }    public void setUsbListener(UsbListener usbListener) {        this.usbListener = usbListener;    }    /**     * USB 操作监听     */    public interface UsbListener {        //USB 插入        void insertUsb(UsbDevice device_add);        //USB 移除        void removeUsb(UsbDevice device_remove);        //获取读取USB权限        void getReadUsbPermission(UsbDevice usbDevice);        //读取USB信息失败        void failedReadUsb(UsbDevice usbDevice);    }}

UsbHelper

UsbHelper是关键的部分，封装了所有的USB文件操作，包括注册/注销USBBroadCastReceiver，获取U盘文件列表，复制文件等，代码如下：

/** * Author ： BlackHao * Time : 2018/5/10 14:53 * Description : USB 操作工具类 * Logs : */public class UsbHelper {    //上下文对象    private Context context;    //USB 设备列表    private UsbMassStorageDevice[] storageDevices;    //USB 广播    private USBBroadCastReceiver mUsbReceiver;    //回调    private USBBroadCastReceiver.UsbListener usbListener;    //当前路径    private UsbFile currentFolder = null;    //TAG    private static String TAG = "UsbHelper";    public UsbHelper(Context context, USBBroadCastReceiver.UsbListener usbListener) {        this.context = context;        this.usbListener = usbListener;        //注册广播        registerReceiver();    }    /**     * 注册 USB 监听广播     */    private void registerReceiver() {        mUsbReceiver = new USBBroadCastReceiver();        mUsbReceiver.setUsbListener(usbListener);        //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(mUsbReceiver, usbDeviceStateFilter);        //注册监听自定义广播        IntentFilter filter = new IntentFilter(ACTION_USB_PERMISSION);        context.registerReceiver(mUsbReceiver, filter);    }    /**     * 读取 USB设备列表     *     * @return USB设备列表     */    public UsbMassStorageDevice[] getDeviceList() {        UsbManager usbManager = (UsbManager) context.getSystemService(Context.USB_SERVICE);        //获取存储设备        storageDevices = UsbMassStorageDevice.getMassStorageDevices(context);        PendingIntent pendingIntent = PendingIntent.getBroadcast(context, 0, new Intent(ACTION_USB_PERMISSION), 0);        //可能有几个 一般只有一个 因为大部分手机只有1个otg插口        for (UsbMassStorageDevice device : storageDevices) {//            Log.e(TAG, device.getUsbDevice().getDeviceName());            //有就直接读取设备是否有权限            if (!usbManager.hasPermission(device.getUsbDevice())) {                //没有权限请求权限                usbManager.requestPermission(device.getUsbDevice(), pendingIntent);            }        }        return storageDevices;    }    /**     * 获取device 根目录文件     *     * @param device USB 存储设备     * @return 设备根目录下文件列表     */    public ArrayList readDevice(UsbMassStorageDevice device) {        ArrayList usbFiles = new ArrayList<>();        try {            //初始化            device.init();            //获取partition            Partition partition = device.getPartitions().get(0);            FileSystem currentFs = partition.getFileSystem();            //获取根目录            UsbFile root = currentFs.getRootDirectory();            currentFolder = root;            //将文件列表添加到ArrayList中            Collections.addAll(usbFiles, root.listFiles());        } catch (Exception e) {            e.printStackTrace();        }        return usbFiles;    }    /**     * 读取 USB 内文件夹下文件列表     *     * @param usbFolder usb文件夹     * @return 文件列表     */    public ArrayList getUsbFolderFileList(UsbFile usbFolder) {        //更换当前目录        currentFolder = usbFolder;        ArrayList usbFiles = new ArrayList<>();        try {            Collections.addAll(usbFiles, usbFolder.listFiles());        } catch (IOException e) {            e.printStackTrace();        }        return usbFiles;    }    /**     * 复制文件到 USB     *     * @param targetFile       需要复制的文件     * @param saveFolder       复制的目标文件夹     * @param progressListener 下载进度回调     * @return 复制结果     */    public boolean saveSDFileToUsb(File targetFile, UsbFile saveFolder, DownloadProgressListener progressListener) {        boolean result;        try {            //USB文件是否存在            boolean isExist = false;            UsbFile saveFile = null;            for (UsbFile usbFile : saveFolder.listFiles()) {                if (usbFile.getName().equals(targetFile.getName())) {                    isExist = true;                    saveFile = usbFile;                }            }            if (isExist) {                //文件已存在，删除文件                saveFile.delete();            }            //创建新文件            saveFile = saveFolder.createFile(targetFile.getName());            //开始写入            FileInputStream fis = new FileInputStream(targetFile);//读取选择的文件的            int avi = fis.available();            UsbFileOutputStream uos = new UsbFileOutputStream(saveFile);            int bytesRead;            byte[] buffer = new byte[1024 * 8];            int writeCount = 0;            while ((bytesRead = fis.read(buffer)) != -1) {                uos.write(buffer, 0, bytesRead);                writeCount += bytesRead;//                Log.e(TAG, "Progress : " + (writeCount * 100 / avi));                if (progressListener != null) {                    //回调下载进度                    progressListener.downloadProgress(writeCount * 100 / avi);                }            }            uos.flush();            fis.close();            uos.close();            result = true;        } catch (final Exception e) {            e.printStackTrace();            result = false;        }        return result;    }    /**     * 复制 USB文件到本地     *     * @param targetFile       需要复制的文件     * @param savePath         复制的目标文件路径     * @param progressListener 下载进度回调     * @return 复制结果     */    public boolean saveUSbFileToLocal(UsbFile targetFile, String savePath,                                      DownloadProgressListener progressListener) {        boolean result;        try {            //开始写入            UsbFileInputStream uis = new UsbFileInputStream(targetFile);//读取选择的文件的            FileOutputStream fos = new FileOutputStream(savePath);            //这里uis.available一直为0//            int avi = uis.available();            long avi = targetFile.getLength();            int writeCount = 0;            int bytesRead;            byte[] buffer = new byte[1024];            while ((bytesRead = uis.read(buffer)) != -1) {                fos.write(buffer, 0, bytesRead);                writeCount += bytesRead;//                Log.e(TAG, "Progress : write : " + writeCount + " All : " + avi);                if (progressListener != null) {                    //回调下载进度                    progressListener.downloadProgress((int) (writeCount * 100 / avi));                }            }            fos.flush();            uis.close();            fos.close();            result = true;        } catch (Exception e) {            e.printStackTrace();            result = false;        }        return result;    }    /**     * 获取上层目录文件夹     *     * @return usbFile : 父目录文件 / null ：无父目录     */    public UsbFile getParentFolder() {        if (currentFolder != null && !currentFolder.isRoot()) {            return currentFolder.getParent();        } else {            return null;        }    }    /**     * 获取当前 USBFolder     */    public UsbFile getCurrentFolder() {        return currentFolder;    }    /**     * 退出 UsbHelper     */    public void finishUsbHelper() {        context.unregisterReceiver(mUsbReceiver);    }    /**     * 下载进度回调     */    public interface DownloadProgressListener {        void downloadProgress(int progress);    }}

DEMO

截图

写了个demo，主要就是Android本地网文件和USB文件相互复制，截图如下：

拷贝文件到U盘

拷贝文件到本地

DEMO源码下载地址

CSDN下载：https://download.csdn.net/download/a512337862/10459222
Github:https://github.com/LuoChen-Hao/BlackHaoUtil

结语

因为本人文字功底有限，所以介绍性的文字很少，但是基本上每句代码都加了注释，理解起来应该不难，如果有任何问题，可以留言。
Demo相关的代码代码未贴出，可以自行下载源码参考。

Android(安卓)基于libaums实现读写U盘文件