[Android Q&A, Help & Troubleshooting] mm11751:
My OS: Android9

Fuction: Showing USB disk's images and copy images to this device when I insert the usb disk

My question:

1.It can read the disk's path and name when I first insert the usb disk, but I can't showing the image from the disk whether using setImageBitmap(bitmap) and setImageURI(uri) of ImageView control

2.It can't show the path on the adb : /mnt/media_rw/, in commont it is will show the usb disk's name , like this: mnt/media_rw/20D3-1E69

my code is below, someone can help me , thanks!

public class TestActivity2 extends AppCompatActivity {

protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
activityLoginBinding = ActivityLoginBinding.inflate(LayoutInflater.from(this));
setContentView(activityLoginBinding.getRoot());
activityLoginBinding.button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
sendBroadcast(new Intent(ACTION_USB_PERMISSION));
}
});
}

/**
* 读取u盘文件
* @param device UsbMassStorageDevice实例对象
*/
private void readAllPicFromUSB(UsbMassStorageDevice device) {
// listImageUSBInfo.clear(); //清空list初始化
try { //遍历文件名
device.init();
// 设备分区
partition = device.getPartitions().get(0);
// 文件系统
currentFs = partition.getFileSystem();
// 获取 U 盘的根目录
mRootFolder = currentFs.getRootDirectory();
readAllPicFromUSB(mRootFolder,currentFs); //递归读取文件
Log.i(TAG, "picSize:" + picSize);
Log.i(TAG,"all pic count:" + picCount + ",all size:" + (long)(picSize / 1024) + "M"); //单位大小为M
picCount = 0; //归零
//所有文件加入list后通知livew刷新
Log.i(TAG,"list size----------------" + listImageUSBInfo.size());
sendBroadcast(new Intent(ACTION_USB_UPDATE_LISTVIEW));
//
} catch (Exception e) {
e.printStackTrace();
Log.i(TAG, "readDevice error:" + e.toString());
}
return;
}

/**
* 获取 U盘读写权限的申请
* @param context 上下文对象
*/
private void permissionRequest(Context context) {
Log.i(TAG,"开始申请设备权限");
try {
// 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.getApplicationContext());
PendingIntent pendingIntent = PendingIntent.getBroadcast(context.getApplicationContext(),
0, new Intent(ACTION_USB_PERMISSION), 0);
if(storageDevices.length == 0){
Log.i(TAG,"请插入可用的 U 盘");
}else{
//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) {
if (usbManager.hasPermission(device.getUsbDevice())) {
Log.i(TAG,"USB已经获取权限");
} else {//无权限申请权限
usbManager.requestPermission(device.getUsbDevice(), pendingIntent);
}
}
}
} catch (Exception e) {
Log.i(TAG,"申请权限异常:" +e.toString());
}
}//end permissionRequest

/**
* USBDevice 转换成UsbMassStorageDevice 对象
* @param usbDevice UsbDevice对象
*/
private UsbMassStorageDevice getUsbMass(UsbDevice usbDevice) {
UsbMassStorageDevice[] storageDevices = UsbMassStorageDevice.getMassStorageDevices(mContext);
for (UsbMassStorageDevice device : storageDevices) {
if (usbDevice.equals(device.getUsbDevice())) {
return device;
}
}
return null;
}//end

@Override
protected void onResume() {
super.onResume();
initUSBService();
Log.i(TAG,"enter onResume");
}//end onresume

@Override
protected void onDestroy() {
super.onDestroy();
unregisterReceiver(usbBroadcast); //注销广播
}

private void initUSBService() { //初始化广播监听器
usbDeviceStateFilter = new IntentFilter();
usbDeviceStateFilter.addAction(ACTION_USB_IN);
usbDeviceStateFilter.addAction(ACTION_USB_OUT);
usbDeviceStateFilter.addAction(ACTION_USB_PERMISSION);
usbDeviceStateFilter.addAction(ACTION_USB_UPDATE_LISTVIEW);
registerReceiver(usbBroadcast,usbDeviceStateFilter);
}

/**
* 广播监听u盘拔插情况
*/
private BroadcastReceiver usbBroadcast = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
mContext=context;
String action=intent.getAction();
switch (action){
case ACTION_USB_PERMISSION: //自定义广播读取u盘文件
try {
UsbDevice usbDevice = intent.getParcelableExtra(UsbManager.EXTRA_DEVICE);
if (intent.getBooleanExtra(UsbManager.EXTRA_PERMISSION_GRANTED,
false)){
Log.i(TAG,"已经有权限111111111111");
if (usbDevice != null) {
readAllPicFromUSB(getUsbMass(usbDevice)); //读取u盘文件
}
else
Log.i(TAG,"没有插入U盘");
}else {
Log.i(TAG,"没有获取读写权限!,开始获取22222222222222");
permissionRequest(mContext); //获取权限
}
}catch (Exception e){
Log.i(TAG, "ACTION_USB_PERMISSION error:" + e.toString());
}
break;
case ACTION_USB_IN:
Log.i(TAG, "插入了u盘");
break;
case ACTION_USB_OUT:
Log.i(TAG,"拔出了u盘");
break;
}
}
};

/**
* 获取本机设备读写权限
*/
private static String[] PERMISSIONS_STORAGE = {
Manifest.permission.READ_EXTERNAL_STORAGE,
Manifest.permission.WRITE_EXTERNAL_STORAGE};
private static int REQUEST_PERMISSION_CODE = 1;
private int ANDROID_VERSION_CURRENT = Build.VERSION.SDK_INT;
private void requestReadAndWriteAccess() {
Log.i(TAG,"now android version is :" + ANDROID_VERSION_CURRENT);
if (ANDROID_VERSION_CURRENT > Build.VERSION_CODES.LOLLIPOP){
if(ActivityCompat.checkSelfPermission(TestActivity2.this, Manifest.permission.WRITE_EXTERNAL_STORAGE)!=
PackageManager.PERMISSION_GRANTED) {
ActivityCompat.requestPermissions(TestActivity2.this, PERMISSIONS_STORAGE, REQUEST_PERMISSION_CODE);
Log.i(TAG,"已经获取读写权限");
}
}
}//end requestReadAndWriteAccess

/**
* 递归读取u盘文件图片文件
* @param usbFile 根文件夹
* @param fileSystem 文件系统
*/
private void readAllPicFromUSB(UsbFile usbFile, FileSystem fileSystem) {
try {
long tmp = 0;
String imgPath = "";
String imgName = "";
UsbFile[] usbFileList = usbFile.listFiles();
for (UsbFile usbFileItem:usbFileList){
if (!usbFileItem.isDirectory()){
String FileEnd = usbFileItem.getName().substring(usbFileItem.getName().lastIndexOf(".") + 1,
usbFileItem.getName().length()).toLowerCase(); //后缀名
if(FileEnd.equals("jpg") || FileEnd.equals("png") || FileEnd.equals("gif")
|| FileEnd.equals("jpeg")|| FileEnd.equals("bmp")){ //过滤出照片
tmp = usbFileItem.getLength() / 1024;
imgPath = USB_PATH_PREFIX + usbFileItem.getAbsolutePath(); //需要绝对地址
imgName = usbFileItem.getName();
Log.i(TAG,"img name:" + imgName + ",path:" + imgPath + ",size:" + tmp + "K");
picCount++;
picSize += tmp; //大小为K
// 加入到list
listImageUSBInfo.add(new ImageInfo(imgPath,imgName));
}
}else
readAllPicFromUSB(usbFileItem,fileSystem);
}
} catch (Exception e) {
e.printStackTrace();
Log.i(TAG,"readDevice error:"+e.toString());
}

}//end
}