Android设备与外接U盘实现数据读取操作的示例

public class MainActivity extends AppCompatActivity implements View.OnClickListener {  //输入的内容  private EditText u_disk_edt;  //写入到U盘  private Button u_disk_write;  //从U盘读取  private Button u_disk_read;  //显示读取的内容  private TextView u_disk_show;  //自定义U盘读写权限  private static final String ACTION_USB_PERMISSION = "com.android.example.USB_PERMISSION";  //当前处接U盘列表  private UsbMassStorageDevice[] storageDevices;  //当前U盘所在文件目录  private UsbFile cFolder;  private final static String U_DISK_FILE_NAME = "u_disk.txt";  private Handler mHandler = new Handler() {    @Override    public void handleMessage(Message msg) {      switch (msg.what) {        case 100:          showToastMsg("保存成功");          break;        case 101:          String txt = msg.obj.toString();          if (!TextUtils.isEmpty(txt))            u_disk_show.setText("读取到的数据是：" + txt);          break;      }    }  };  @Override  protected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.activity_main);    initViews();  }  private void initViews() {    u_disk_edt = (EditText) findViewById(R.id.u_disk_edt);    u_disk_write = (Button) findViewById(R.id.u_disk_write);    u_disk_read = (Button) findViewById(R.id.u_disk_read);    u_disk_show = (TextView) findViewById(R.id.u_disk_show);    u_disk_write.setOnClickListener(this);    u_disk_read.setOnClickListener(this);  }  @Override  public void onClick(View view) {    switch (view.getId()) {      case R.id.u_disk_write:        final String content = u_disk_edt.getText().toString().trim();        mHandler.post(new Runnable() {          @Override          public void run() {            saveText2UDisk(content);          }        });        break;      case R.id.u_disk_read:        mHandler.post(new Runnable() {          @Override          public void run() {            readFromUDisk();          }        });        break;    }  }  private void readFromUDisk() {    UsbFile[] usbFiles = new UsbFile[0];    try {      usbFiles = cFolder.listFiles();    } catch (IOException e) {      e.printStackTrace();    }    if (null != usbFiles && usbFiles.length > 0) {      for (UsbFile usbFile : usbFiles) {        if (usbFile.getName().equals(U_DISK_FILE_NAME)) {          readTxtFromUDisk(usbFile);        }      }    }  }  /**   * @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(file, cFolder);      mHandler.sendEmptyMessage(100);    }  }  /**   * @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 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;      }    }  };  /**   * @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");    }  }  private UsbMassStorageDevice getUsbMass(UsbDevice usbDevice) {    for (UsbMassStorageDevice device : storageDevices) {      if (usbDevice.equals(device.getUsbDevice())) {        return device;      }    }    return null;  }  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      FileSystem 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    } catch (Exception e) {      e.printStackTrace();    }  }  private void showToastMsg(String msg) {    Toast.makeText(this, msg, Toast.LENGTH_SHORT).show();  }  private void readTxtFromUDisk(UsbFile usbFile) {    UsbFile descFile = usbFile;    //读取文件内容    InputStream is = new UsbFileInputStream(descFile);    //读取秘钥中的数据进行匹配    StringBuilder sb = new StringBuilder();    BufferedReader bufferedReader = null;    try {      bufferedReader = new BufferedReader(new InputStreamReader(is));      String read;      while ((read = bufferedReader.readLine()) != null) {        sb.append(read);      }      Message msg = mHandler.obtainMessage();      msg.what = 101;      msg.obj = read;      mHandler.sendMessage(msg);    } catch (Exception e) {      e.printStackTrace();    } finally {      try {        if (bufferedReader != null) {          bufferedReader.close();        }      } catch (IOException e) {        e.printStackTrace();      }    }  }}

<?xml version="1.0" encoding="utf-8"?><LinearLayout    xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    tools:context="com.ldm.androidudisk.MainActivity"    android:orientation="vertical">  <TextView      android:layout_width="wrap_content"      android:layout_height="wrap_content"      android:text="Android盒子外接U盘文件读写测试DEMO"      android:layout_gravity="center"      android:layout_margin="10dp"      />  <EditText      android:id="@+id/u_disk_edt"      android:layout_width="match_parent"      android:layout_height="wrap_content"      android:layout_margin="10dp"      android:hint="输入要保存到U盘中的文字内容"/>  <Button      android:id="@+id/u_disk_write"      android:layout_width="match_parent"      android:layout_height="wrap_content"      android:layout_margin="10dp"      android:gravity="center"      android:text="往U盘中写入数据"/>  <Button      android:id="@+id/u_disk_read"      android:layout_width="match_parent"      android:layout_height="wrap_content"      android:layout_margin="10dp"      android:gravity="center"      android:text="从U盘中读取数据"/>  <TextView      android:id="@+id/u_disk_show"      android:layout_width="wrap_content"      android:layout_height="wrap_content"      android:layout_gravity="center"      android:layout_marginLeft="10dp"      /></LinearLayout>

package com.ldm.androidudisk.utils;import android.os.Environment;import com.github.mjdev.libaums.fs.UsbFile;import com.github.mjdev.libaums.fs.UsbFileOutputStream;import java.io.Closeable;import java.io.File;import java.io.FileInputStream;import java.io.IOException;import java.io.InputStream;import java.io.OutputStream;import static android.os.Environment.getExternalStorageDirectory;/** * 文件操作工具类 * * @author ldm * @description： * @date 2016-4-28 下午3:17:10 */public final 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();  }  /**   * @description 把本地文件写入到U盘中   * @author ldm   * @time 2017/8/22 10:22   */  public static void saveSDFile2OTG(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();    }  }}

compile 'com.github.mjdev:libaums:0.5.5'

 <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>  <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>