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

痛定思痛。 2022-10-03 00:47 315阅读 0赞

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][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：

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。

[https_github.com_magnusja_libaums]: https://github.com/magnusja/libaums