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Android-USB-OTG-读写U盘文件

详细信息:

参考:
https://developer.android.com/guide/topics/connectivity/usb/host.html
https://blog.csdn.net/qq_29924041/article/details/80141514

本文介绍Android手机通过OTG数据线读写USB存储设备(U盘,移动硬盘,存储卡)的两种方法

方法一: 直接和USB设备建立连接,借助第三方库libaums识别U盘的文件系统

由于libaums只支持FAT32文件系统,所以U盘的格式化必须采用FAT32!
该库的GitHub地址: https://github.com/magnusja/libaums

1.权限

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" /> 
// 手机必须支持USB主机特性(OTG)
<uses-feature android:name="android.hardware.usb.host" />

2.监听USB插入/拔出

private static final String ACTION_USB_PERMISSION = "com.demo.otgusb.USB_PERMISSION";
private UsbManager mUsbManager;
private PendingIntent mPermissionIntent; 
private BroadcastReceiver mUsbReceiver = new BroadcastReceiver() {
 public void onReceive(Context context, Intent intent) {
 Log.d(TAG, "onReceive: " + intent);
 String action = intent.getAction();
 if (action == null)
 return;
 switch (action) {
 case ACTION_USB_PERMISSION://用户授权广播
 synchronized (this) {
 if (intent.getBooleanExtra(UsbManager.EXTRA_PERMISSION_GRANTED, false)) { //允许权限申请
 test();
 } else {
 logShow("用户未授权,访问USB设备失败");
 }
 }
 break;
 case UsbManager.ACTION_USB_DEVICE_ATTACHED://USB设备插入广播
 logShow("USB设备插入");
 break;
 case UsbManager.ACTION_USB_DEVICE_DETACHED://USB设备拔出广播
 logShow("USB设备拔出");
 break;
 }
 }
};
private void init() { 
 //USB管理器
 mUsbManager = (UsbManager) getSystemService(Context.USB_SERVICE);
 mPermissionIntent = PendingIntent.getBroadcast(this, 0, new Intent(ACTION_USB_PERMISSION), 0);
 
 //注册广播,监听USB插入和拔出
 IntentFilter intentFilter = new IntentFilter();
 intentFilter.addAction(UsbManager.ACTION_USB_DEVICE_ATTACHED);
 intentFilter.addAction(UsbManager.ACTION_USB_DEVICE_DETACHED);
 intentFilter.addAction(ACTION_USB_PERMISSION);
 registerReceiver(mUsbReceiver, intentFilter);
 //读写权限
 if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
 requestPermissions(new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE,
 Manifest.permission.READ_EXTERNAL_STORAGE}, 111);
 }
}

3.使用libaums库读写U盘文件

private void test() {
 try {
 UsbMassStorageDevice[] storageDevices = UsbMassStorageDevice.getMassStorageDevices(this);
 for (UsbMassStorageDevice storageDevice : storageDevices) { //一般手机只有一个USB设备
 // 申请USB权限
 if (!mUsbManager.hasPermission(storageDevice.getUsbDevice())) {
 mUsbManager.requestPermission(storageDevice.getUsbDevice(), mPermissionIntent);
 break;
 }
 // 初始化
 storageDevice.init();
 // 获取分区
 List<Partition> partitions = storageDevice.getPartitions();
 if (partitions.size() == 0) {
 logShow("错误: 读取分区失败");
 return;
 }
 // 仅使用第一分区
 FileSystem fileSystem = partitions.get(0).getFileSystem();
 logShow("Volume Label: " + fileSystem.getVolumeLabel());
 logShow("Capacity: " + fSize(fileSystem.getCapacity()));
 logShow("Occupied Space: " + fSize(fileSystem.getOccupiedSpace()));
 logShow("Free Space: " + fSize(fileSystem.getFreeSpace()));
 logShow("Chunk size: " + fSize(fileSystem.getChunkSize()));
 UsbFile root = fileSystem.getRootDirectory();
 UsbFile[] files = root.listFiles();
 for (UsbFile file : files)
 logShow("文件: " + file.getName());
 // 新建文件
 UsbFile newFile = root.createFile("hello_" + System.currentTimeMillis() + ".txt");
 logShow("新建文件: " + newFile.getName());
 // 写文件
 // OutputStream os = new UsbFileOutputStream(newFile);
 OutputStream os = UsbFileStreamFactory.createBufferedOutputStream(newFile, fileSystem);
 os.write(("hi_" + System.currentTimeMillis()).getBytes());
 os.close();
 logShow("写文件: " + newFile.getName());
 // 读文件
 // InputStream is = new UsbFileInputStream(newFile);
 InputStream is = UsbFileStreamFactory.createBufferedInputStream(newFile, fileSystem);
 byte[] buffer = new byte[fileSystem.getChunkSize()];
 int len;
 File sdFile = new File("/sdcard/111");
 sdFile.mkdirs();
 FileOutputStream sdOut = new FileOutputStream(sdFile.getAbsolutePath() + "/" + newFile.getName());
 while ((len = is.read(buffer)) != -1) {
 sdOut.write(buffer, 0, len);
 }
 is.close();
 sdOut.close();
 logShow("读文件: " + newFile.getName() + " ->复制到/sdcard/111/");
 storageDevice.close();
 }
 } catch (Exception e) {
 logShow("错误: " + e);
 }
}
public static String fSize(long sizeInByte) {
 if (sizeInByte < 1024)
 return String.format("%s", sizeInByte);
 else if (sizeInByte < 1024 * 1024)
 return String.format(Locale.CANADA, "%.2fKB", sizeInByte / 1024.);
 else if (sizeInByte < 1024 * 1024 * 1024)
 return String.format(Locale.CANADA, "%.2fMB", sizeInByte / 1024. / 1024);
 else
 return String.format(Locale.CANADA, "%.2fGB", sizeInByte / 1024. / 1024 / 1024);
}

方法二: 获取U盘的挂载路径,直接读写U盘(就像挂载sdcard读写文件)

对于U盘的文件系统,只依赖于手机系统是否支持,无需我们做额外工作(所有Android手机都支持FAT32,有个别手机还支持NTFS)
但是有些手机无法获取挂载路径(如小米等,就算通过mount命令找到挂载路径也没有权限读写),所以该方法通用性其实不如方法一!

1.通过MEDIA广播获取挂载路径

// 注册系统广播
<receiver android:name=".MediaReceiver">
 <intent-filter>
 <action android:name="android.intent.action.MEDIA_CHECKING" />
 <action android:name="android.intent.action.MEDIA_MOUNTED" />
 <action android:name="android.intent.action.MEDIA_EJECT" />
 <action android:name="android.intent.action.MEDIA_UNMOUNTED" />
 <data android:scheme="file" />
 </intent-filter>
</receiver>
// 获取USB挂载路径
public class MediaReceiver extends BroadcastReceiver { 
 @Override
 public void onReceive(Context context, Intent intent) {
 switch (intent.getAction()) {
 case Intent.ACTION_MEDIA_CHECKING:
 break;
 case Intent.ACTION_MEDIA_MOUNTED:
 // 获取挂载路径, 读取U盘文件
 Uri uri = intent.getData();
 if (uri != null) {
 String filePath = uri.getPath();
 File rootFile = new File(filePath);
 for (File file : rootFile.listFiles()) {
 // 文件列表...
 }
 }
 break;
 case Intent.ACTION_MEDIA_EJECT:
 break;
 case Intent.ACTION_MEDIA_UNMOUNTED:
 break;
 }
 }
}

2.通过反射系统方法获取挂载路径

public static List<String> getUsbPaths(Context cxt) {
 List<String> usbPaths = new ArrayList<>();
 try {
 StorageManager srgMgr = (StorageManager) cxt.getSystemService(Context.STORAGE_SERVICE);
 Class<StorageManager> srgMgrClass = StorageManager.class;
 String[] paths = (String[]) srgMgrClass.getMethod("getVolumePaths").invoke(srgMgr);
 for (String path : paths) {
 Object volumeState = srgMgrClass.getMethod("getVolumeState", String.class).invoke(srgMgr, path);
 if (!path.contains("emulated") && Environment.MEDIA_MOUNTED.equals(volumeState))
 usbPaths.add(path);
 }
 } catch (Exception e) {
 e.printStackTrace();
 }
 return usbPaths;
}

简书: https://www.jianshu.com/p/a32e376ea70e
CSDN: https://blog.csdn.net/qq_32115439/article/details/80918046
GitHub博客: http://lioil.win/2018/07/04/Android-USB-OTG.html
Coding博客: http://c.lioil.win/2018/07/04/Android-USB-OTG.html