首先给予足够的读写权限：
<uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<uses-permission
android:name="android.hardware.usb.host"
android:required="false" />
<uses-feature
android:name="android.hardware.usb.host"
android:required="true" />其次添加一个U盘读写操作的依赖包，我用的也是大家都推荐的：
compile 'com.github.mjdev:libaums:0.5.5'继续上代码：首先是写操作（注意：需要你的手机root了才可以）
第一步：注册广播
/**
* @description OTG广播注册
* @author ldm
* @time 2017/9/1 17:19
*/
private void registerUDiskReceiver() {
//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);
registerReceiver(mOtgReceiver, usbDeviceStateFilter);
//注册监听自定义广播
IntentFilter filter = new IntentFilter(ACTION_USB_PERMISSION);
registerReceiver(mOtgReceiver, filter);
}/**
* @description OTG广播，监听U盘的插入及拔出
* @author ldm
* @time 2017/9/1 17:20
* @param
*/
private BroadcastReceiver mOtgReceiver = new BroadcastReceiver() {
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 = intent.getParcelableExtra(UsbManager.EXTRA_DEVICE);
//允许权限申请
if (intent.getBooleanExtra(UsbManager.EXTRA_PERMISSION_GRANTED, false)) {
if (usbDevice != null) {
//用户已授权，可以进行读取操作
readDevice(getUsbMass(usbDevice));
} else {
showToastMsg("没有插入U盘");
}
} else {
showToastMsg("未获取到U盘权限");
}
break;
case UsbManager.ACTION_USB_DEVICE_ATTACHED://接收到U盘设备插入广播
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
redUDiskDevsList();
}
break;
case UsbManager.ACTION_USB_DEVICE_DETACHED://接收到U盘设设备拔出广播
showToastMsg("U盘已拔出");
break;
}
}
};设备读取
/**
* @description U盘设备读取
* @author ldm
* @time 2017/9/1 17:20
*/
private void redUDiskDevsList() {
//设备管理器
UsbManager usbManager = (UsbManager) getSystemService(Context.USB_SERVICE);
//获取U盘存储设备
storageDevices = UsbMassStorageDevice.getMassStorageDevices(this);
PendingIntent pendingIntent = PendingIntent.getBroadcast(this, 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.hasPermission(device.getUsbDevice())) {
readDevice(device);
} else {
//没有权限，进行申请
usbManager.requestPermission(device.getUsbDevice(), pendingIntent);
}
}
if (storageDevices.length == 0) {
showToastMsg("请插入可用的U盘");
}
}设备写入：
/**
* @description 保存数据到U盘，目前是保存到根目录的
* @author ldm
* @time 2017/9/1 17:17
*/
private void saveText2UDisk(String content) {
//项目中也把文件保存在了SD卡，其实可以直接把文本读取到U盘指定文件
File file = FileUtil.getSaveFile(getPackageName()
+ File.separator + FileUtil.DEFAULT_BIN_DIR,
U_DISK_FILE_NAME);
try {
FileWriter fw = new FileWriter(file);
fw.write(content);
fw.close();
} catch (IOException e) {
e.printStackTrace();
}
if (null != cFolder) {
FileUtil.saveSDFile2OTG(MainActivity.this,file, cFolder);
mHandler.sendEmptyMessage(100);
}
}文件操作类：
public class FileUtil {
public static final String DEFAULT_BIN_DIR = "usb";
/**
* 检测SD卡是否存在
*/
public static boolean checkSDcard() {
return Environment.MEDIA_MOUNTED.equals(Environment
.getExternalStorageState());
}
/**
* 从指定文件夹获取文件
*
* @return 如果文件不存在则创建, 如果如果无法创建文件或文件名为空则返回null
*/
public static File getSaveFile(String folderPath, String fileNmae) {
File file = new File(getSavePath(folderPath) + File.separator
+ fileNmae);
try {
file.createNewFile();
} catch (IOException e) {
e.printStackTrace();
}
return file;
}
/**
* 获取SD卡下指定文件夹的绝对路径
*
* @return 返回SD卡下的指定文件夹的绝对路径
*/
public static String getSavePath(String folderName) {
return getSaveFolder(folderName).getAbsolutePath();
}
/**
* 获取文件夹对象
*
* @return 返回SD卡下的指定文件夹对象，若文件夹不存在则创建
*/
public static File getSaveFolder(String folderName) {
File file = new File(getExternalStorageDirectory()
.getAbsoluteFile()
+ File.separator
+ folderName
+ File.separator);
file.mkdirs();
return file;
}
/**
* 关闭流
*/
public static void closeIO(Closeable... closeables) {
if (null == closeables || closeables.length <= 0) {
return;
}
for (Closeable cb : closeables) {
try {
if (null == cb) {
continue;
}
cb.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
private static void redFileStream(OutputStream os, InputStream is) throws IOException {
int bytesRead = 0;
byte[] buffer = new byte[1024 * 8];
while ((bytesRead = is.read(buffer)) != -1) {
os.write(buffer, 0, bytesRead);
}
os.flush();
os.close();
is.close();
}
public static List<String> getAllExterSdcardPath()
{
List<String> SdList = new ArrayList<String>();
String firstPath = Environment.getExternalStorageDirectory().getPath();
try
{
Runtime runtime = Runtime.getRuntime();
// 运行mount命令，获取命令的输出，得到系统中挂载的所有目录
Process proc = runtime.exec("mount");
InputStream is = proc.getInputStream();
InputStreamReader isr = new InputStreamReader(is);
String line;
BufferedReader br = new BufferedReader(isr);
while ((line = br.readLine()) != null)
{
Log.d("", line);
// 将常见的linux分区过滤掉
if (line.contains("proc") || line.contains("tmpfs") || line.contains("media") || line.contains("asec") || line.contains("secure") || line.contains("system") || line.contains("cache")
|| line.contains("sys") || line.contains("data") || line.contains("shell") || line.contains("root") || line.contains("acct") || line.contains("misc") || line.contains("obb"))
{
continue;
}
// 下面这些分区是我们需要的
if (line.contains("fat") || line.contains("fuse") || (line.contains("ntfs")))
{
// 将mount命令获取的列表分割，items[0]为设备名，items[1]为挂载路径
String items[] = line.split(" ");
if (items != null && items.length > 1)
{
String path = items[1].toLowerCase(Locale.getDefault());
// 添加一些判断，确保是sd卡，如果是otg等挂载方式，可以具体分析并添加判断条件
if (path != null && !SdList.contains(path) && path.contains("sd"))
SdList.add(items[1]);
}
}
}
} catch (Exception e)
{
// TODO Auto-generated catch block
e.printStackTrace();
}
if (!SdList.contains(firstPath))
{
SdList.add(firstPath);
}
return SdList;
}
/**
* @description 把本地文件写入到U盘中
* @author ldm
* @time 2017/8/22 10:22
*/
public static void saveSDFile2OTG(Context context,final File f, final UsbFile usbFile) {
UsbFile uFile = null;
FileInputStream fis = null;
try {//开始写入
fis = new FileInputStream(f);//读取选择的文件的
if (usbFile.isDirectory()) {//如果选择是个文件夹
UsbFile[] usbFiles = usbFile.listFiles();
if (usbFiles != null && usbFiles.length > 0) {
for (UsbFile file : usbFiles) {
if (file.getName().equals(f.getName())) {
file.delete();
}
}
}
uFile = usbFile.createFile(f.getName());
UsbFileOutputStream uos = new UsbFileOutputStream(uFile);
try {
redFileStream(uos, fis);
} catch (IOException e) {
e.printStackTrace();
}
}
} catch (final Exception e) {
e.printStackTrace();
Toast.makeText(context,e.toString(),Toast.LENGTH_LONG).show();
}
}
}private final static String U_DISK_FILE_NAME = "****.txt";//星号写自己要写入文件的文件名读取操作：Ps：一开始以为挺简单，后面发现没那么简单
获取UsbDevice
private UsbMassStorageDevice getUsbMass(UsbDevice usbDevice) {
if(usbDevice!=null){
for (UsbMassStorageDevice device : storageDevices) {
if (usbDevice.equals(device.getUsbDevice())) {
return device;
}
}
}
return null;
}初始化调用：
private void readDevice(UsbMassStorageDevice device) {
try {
device.init();//初始化
//设备分区
Partition partition = device.getPartitions().get(0);
//文件系统
currentFs = partition.getFileSystem();
currentFs.getVolumeLabel();//可以获取到设备的标识
//通过FileSystem可以获取当前U盘的一些存储信息，包括剩余空间大小，容量等等
Log.e("Capacity: ", currentFs.getCapacity() + "");
Log.e("Occupied Space: ", currentFs.getOccupiedSpace() + "");
Log.e("Free Space: ", currentFs.getFreeSpace() + "");
Log.e("Chunk size: ", currentFs.getChunkSize() + "");
cFolder = currentFs.getRootDirectory();//设置当前文件对象为根目录
UsbFile[] usbFiles=cFolder.listFiles();
if (null != usbFiles && usbFiles.length > 0) {
for (UsbFile usbFile : usbFiles) {
if (usbFile.getName().equals(U_DISK_FILE_NAME)) {
readFile(usbFile);
// readTxtFromUDisk(usbFile);
}
}
}
} catch (Exception e) {
e.printStackTrace();
android.widget.Toast.makeText(AddPwsAddressActivity.this,e.toString(), android.widget.Toast.LENGTH_LONG).show();
}
}private void readFile(final UsbFile uFile) {
String sdPath = SDUtils.getSDPath();//获取sd根目录 创建一个同名文件
String filePath = sdPath + "/" + uFile.getName();
final File f = new File(filePath);
if (!f.exists()) {
try {
f.createNewFile();
//设置视图
//执行线程
executorService.execute(new Runnable() {
@Override
public void run() {
try {
FileOutputStream os = new FileOutputStream(f);
InputStream is = new UsbFileInputStream(uFile);
final String bt = redFileStream(os, is);
runOnUiThread(new Runnable() {
@Override
public void run() {
android.widget.Toast.makeText(AddPwsAddressActivity.this,bt, android.widget.Toast.LENGTH_LONG).show();
Message msg = mHandler.obtainMessage();
msg.what = 101;
android.widget.Toast.makeText(AddPwsAddressActivity.this,bt, android.widget.Toast.LENGTH_LONG).show();
msg.obj = bt;
mHandler.sendMessage(msg);
}
});
} catch (final Exception e) {
e.printStackTrace();
}
}
});
} catch (final Exception e) {
e.printStackTrace();
}
}else {
try {
executorService.execute(new Runnable() {
@Override
public void run() {
try {
FileOutputStream os = new FileOutputStream(f);
InputStream is = new UsbFileInputStream(uFile);
final String bt = redFileStream(os, is);
runOnUiThread(new Runnable() {
@Override
public void run() {
android.widget.Toast.makeText(AddPwsAddressActivity.this,bt, android.widget.Toast.LENGTH_LONG).show();
Message msg = mHandler.obtainMessage();
msg.what = 101;
android.widget.Toast.makeText(AddPwsAddressActivity.this,bt, android.widget.Toast.LENGTH_LONG).show();
msg.obj = bt;
mHandler.sendMessage(msg);
}
});
} catch (final Exception e) {
e.printStackTrace();
}
}
});
} catch (final Exception e) {
e.printStackTrace();
}
}
}private Handler mHandler = new Handler() {
@Override
public void handleMessage(Message msg) {
switch (msg.what) {
case 100:
showToastMsg("保存成功");
break;
case 101:
if(msg.obj==null){
Toast.makeText(MainActivity.this,"空的",Toast.LENGTH_LONG).show();
}else{
String txt = msg.obj.toString();
if (!TextUtils.isEmpty(txt))
u_disk_show.setText("读取到的数据是：" + txt);
}
break;
}
}
};
Ps:别忘记反注册广播
sd卡工具类：
public class SDUtils {
private static final String TAG = "文件工具类";
public static String getSDPath() {
File sdDir = null;
boolean sdCardExist = Environment.getExternalStorageState()
.equals(Environment.MEDIA_MOUNTED); //判断sd卡是否存在
if (sdCardExist) {
sdDir = Environment.getExternalStorageDirectory();//获取跟目录
// sdDir1 = Environment.getDataDirectory();
// sdDir2 = Environment.getRootDirectory();
} else {
Log.d(TAG, "getSDPath: sd卡不存在");
}
Log.d(TAG, "getSDPath: " + sdDir.getAbsolutePath());
return sdDir.getAbsolutePath();
}本文章为转载内容，我们尊重原作者对文章享有的著作权。如有内容错误或侵权问题，欢迎原作者联系我们进行内容更正或删除文章。
