Android P检测USB插入拔出消息并基于libaums实现读取USB文件

Android设备中检测USB插入消息，并且从USB中读取文件。

一、导入libaums包

libaums开源项目地址：https://github.com/magnusja/libaums
build.gradle文件中引用libaums：
implementation 'com.github.mjdev:libaums:+’

或者编译出libaums-0.6.0.jar，导入jar包：
implementation files(‘libs/libaums-0.6.0.jar’)

二、新建一个广播，接收USB插入消息，并读取Usb文件

检测到Usb插入：UsbManager.ACTION_USB_DEVICE_ATTACHED；
检测到Usb拔出：UsbManager.ACTION_USB_DEVICE_DETACHED.
readUsbDeviceList()获取Usb设备请申请访问权限或者调用readDevice读取Usb文件；
readDevice()为读取Usb中文件操作；

//Usb中要读取的文件
private static final String MCU_VERSION_FILE = "version.txt";
public class UsbIntentReceiver extends BroadcastReceiver {
private static final String TAG = "UsbIntentReceiver";
private static final String ACTION_USB_PERMISSION = "com.android.example.USB_PERMISSION";
//Usb list
private static UsbMassStorageDevice[] mStorageDevices;
//Usb path
private UsbFile mUsbPath;
@Override
public void onReceive(Context context, Intent intent) {
final UsbDevice device = intent.getExtras().getParcelable(UsbManager.EXTRA_DEVICE);
switch (intent.getAction()) {
case UsbManager.ACTION_USB_DEVICE_ATTACHED:
//检测到USB插入，读取Usb设备
readUsbDeviceList(context);
break;
case UsbManager.ACTION_USB_DEVICE_DETACHED:
//检测到Usb拔出
break;
case ACTION_USB_PERMISSION:
//通知一个弹框，询问用户对Usb的访问权限，用户选择ok，表示可以访问Usb设备
//申请对USB的读写权限
//返回true，表示用户选择了ok，同意进行读取Usb
if(intent.getBooleanExtra(UsbManager.EXTRA_PERMISSION_GRANTED,false)){
if(device != null ){
//已经获取到Usb访问权限，读取设备
readDevice(context,getUsbMass(device));
}
}
break;
}
}
private void readUsbDeviceList(Context context) {
//获取当前Usb设备
mStorageDevices = UsbMassStorageDevice.getMassStorageDevices(context);
//打印当前有几个Usb设备
Log.i(TAG,"sunxiaolin,readUsbDeviceList,mStorageDevices.length=" + mStorageDevices.length);
//创建一个弹框类型ACTION_USB_PERMISSION
UsbManager usbManager = (UsbManager) context.getSystemService(Context.USB_SERVICE);
PendingIntent pendingIntent = PendingIntent.getBroadcast(context, 0, new Intent(ACTION_USB_PERMISSION), 0);
for (UsbMassStorageDevice device : mStorageDevices) {
if (usbManager.hasPermission(device.getUsbDevice())) {
//已经获取到Usb访问权限，直接读取设备
readDevice(context, device);
}else {
//通知一个弹框，询问用户对Usb的访问权限，用户选择ok，表示可以访问Usb设备
//没有访问权限，申请权限
usbManager.requestPermission(device.getUsbDevice(), pendingIntent);
}
}
}
private UsbMassStorageDevice getUsbMass(UsbDevice usbDevice){
Log.i(TAG,"sunxiaolin:getUsbMass,usbDevice=" + usbDevice);
if( mStorageDevices != null && mStorageDevices.length > 0){
for( UsbMassStorageDevice device : mStorageDevices){
Log.i(TAG,"sunxiaolin:getUsbMass,device=" + device);
if(usbDevice.equals(device.getUsbDevice())){
return device;
}
}
}
return null;
}
private void readDevice(Context context, UsbMassStorageDevice device) {
try {
device.init();
// Only uses the first partition on the device
Partition partion = device.getPartitions().get(0);
Log.i(TAG,"sunxiaolin,partion=" + partion);
FileSystem currentFs = partion.getFileSystem();
//Toast.makeText(context, "getRootDirectory: " + currentFs.getRootDirectory().getName(), Toast.LENGTH_LONG).show();
Log.d(TAG, "Capacity: " + currentFs.getCapacity());
//Toast.makeText(context, "Capacity: " + currentFs.getCapacity(), Toast.LENGTH_LONG).show();
Log.d(TAG, "Occupied Space: " + currentFs.getOccupiedSpace());
//Toast.makeText(context, "Occupied Space: " + currentFs.getOccupiedSpace(), Toast.LENGTH_LONG).show();
Log.d(TAG, "Free Space: " + currentFs.getFreeSpace());
//Toast.makeText(context, "Free Space: " + currentFs.getFreeSpace(), Toast.LENGTH_LONG).show();
Log.d(TAG, "Chunk size: " + currentFs.getChunkSize());
//Toast.makeText(context, "Chunk size: " + currentFs.getChunkSize(), Toast.LENGTH_LONG).show();
mUsbPath = currentFs.getRootDirectory();
///< 读取当前目录下的文件
readDataFromUsb(context);
} catch (Exception e) {
e.printStackTrace();
}
}
private void readDataFromUsb(Context context) {
UsbFile[] usbFiles = new UsbFile[0];
try {
usbFiles = mUsbPath.listFiles();
} catch (IOException e) {
e.printStackTrace();
}
if (null != usbFiles && usbFiles.length > 0) {
for (UsbFile usbFile : usbFiles) {
Log.i(TAG,"sunxiaolin,usbFile=" + usbFile);
if (usbFile.getName().equals(VERSION_FILE)) {
readTxtFromUsb(usbFile);
Toast.makeText(context, "usbFile.getName(): " + usbFile.getName(), Toast.LENGTH_LONG).show();
}
}
}
}
private void readTxtFromUsb(UsbFile usbFile) {
UsbFile descFile = usbFile;
//mMcuUpdateFile = usbFile;
InputStream is = new UsbFileInputStream(descFile);
StringBuilder sb = new StringBuilder();
BufferedReader bufferedReader = null;
try {
bufferedReader = new BufferedReader(new InputStreamReader(is));
String read;
while ((read = bufferedReader.readLine()) != null) {
sb.append(read);
Log.i(TAG,"sunxiaolin,readTxtFromUDisk,readResult=" + read);
}
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
if (bufferedReader != null) {
bufferedReader.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
}

三、在AndroidManifest.xml中申请权限和配置广播

<uses-permission android:name=”android.permission.READ_EXTERNAL_STORAGE” />
<uses-permission android:name=”android.permission.WRITE_EXTERNAL_STORAGE” />
<receiver
android:name=".UsbIntentReceiver"
android:exported="true">
<intent-filter>
<action android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED" />
<action android:name="android.hardware.usb.action.USB_DEVICE_DETACHED" />
<action android:name="com.android.example.USB_PERMISSION" />
</intent-filter>
<meta-data
android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED"
android:resource="@xml/device_filter" />
</receiver>

xml文件device_filter：

<resources>
<!-- filter for MTP/PTP devices -->
<usb-device class="255" subclass="255" protocol="0" />
<usb-device class="6" subclass="1" protocol="1" />
</resources>

总结：其中有一个申请权限，弹出框然该用户选择允许访问usb设备，是安卓为了提高用户隐私采取的措施，提醒用户哪些权限被使用。如果去掉还是要在系统中去修改权限。

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