一步一步教你簡單完成 Android USB開發

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項目中有一個新的需求，要求可以串連一個USB體溫槍，APP可以從體溫槍中讀取到體溫資料，一番搜尋之後發現一個封裝很棒的USB通訊庫。
github地址：usb-serial-for-android

準備工作

1. 從 github 上 clone 這個庫的源檔案

2. 在Android Studio中引入模組
   

3. 在build.gradle中添加依賴compile project(path: ‘:usbSerialForAndroid‘)

4. 複製 device_filter.xml 到項目的 res/xml/ 檔案夾下
   

5. 配置 AndroidManifest.xml 檔案

<uses-feature android:name="android.hardware.usb.host" /><application>    <activity        android:name="..."        ...>      <intent-filter>        <action android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED" />      </intent-filter>      <meta-data          android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED"          android:resource="@xml/device_filter" />    </activity></application>

使用

範例程式碼解析：

// 擷取系統服務得到UsbManager執行個體UsbManager manager = (UsbManager) getSystemService(Context.USB_SERVICE);//尋找所有插入的裝置List<UsbSerialDriver> availableDrivers = UsbSerialProber.getDefaultProber().findAllDrivers(manager);if (availableDrivers.isEmpty()) {  return;}// 開啟裝置，建立通訊串連UsbSerialDriver driver = availableDrivers.get(0);UsbDeviceConnection connection = manager.openDevice(driver.getDevice());if (connection == null) {  // You probably need to call UsbManager.requestPermission(driver.getDevice(), ..)  return;}//開啟連接埠，設定連接埠參數，讀取資料UsbSerialPort port = driver.getPorts().get(0);try {  port.open(connection);//四個參數分別是：傳輸速率，資料位元，停止位，校正位  port.setParameters(115200, 8, UsbSerialPort.STOPBITS_1, UsbSerialPort.PARITY_NONE);  byte buffer[] = new byte[16];  int numBytesRead = port.read(buffer, 1000);  Log.d(TAG, "Read " + numBytesRead + " bytes.");} catch (IOException e) {  // Deal with error.} finally {  port.close();}

上述代碼是庫作者寫的一段範例程式碼，可以看出使用上非常簡單，下面的代碼示範了如何將USB操作都封裝到一個類裡。

public class TemperatureUsbControl {    private static final String TAG = TemperatureUsbControl.class.getSimpleName();    private static final String TEMPERATURE_USB_VENDOR_ID = "067B";     //供應商id    private static final String TEMPERATURE_USB_PRODUCT_ID = "2303";    //產品id    private Context mContext;    private UsbManager mUsbManager; //USB管理器    private UsbSerialPort sTemperatureUsbPort = null;  //接體溫槍的usb連接埠    private SerialInputOutputManager mSerialIoManager;  //輸入輸出管理器（本質是一個Runnable）    private final ExecutorService mExecutor = Executors.newSingleThreadExecutor();  //用於不斷從連接埠讀取資料    //資料輸入輸出監聽器    private final SerialInputOutputManager.Listener mListener =            new SerialInputOutputManager.Listener() {                @Override                public void onRunError(Exception e) {                    Log.d(TAG, "Runner stopped.");                }                @Override                public void onNewData(final byte[] data) {                    Log.d(TAG, "new data.");                }            };    public TemperatureUsbControl(Context context) {        mContext = context;    }    public void initUsbControl() {        mUsbManager = (UsbManager) mContext.getSystemService(Context.USB_SERVICE);        //全部裝置        List<UsbSerialDriver> usbSerialDrivers = UsbSerialProber.getDefaultProber().findAllDrivers(mUsbManager);        //全部連接埠        List<UsbSerialPort> usbSerialPorts = new ArrayList<UsbSerialPort>();        for (UsbSerialDriver driver : usbSerialDrivers) {            List<UsbSerialPort> ports = driver.getPorts();            Log.d(TAG, String.format("+ %s: %s port%s",                    driver, Integer.valueOf(ports.size()), ports.size() == 1 ? "" : "s"));            usbSerialPorts.addAll(ports);        }        String vendorId;        String productId;        //校正裝置，裝置是 2303裝置        for (UsbSerialPort port : usbSerialPorts) {            UsbSerialDriver driver = port.getDriver();            UsbDevice device = driver.getDevice();            vendorId = HexDump.toHexString((short) device.getVendorId());            productId = HexDump.toHexString((short) device.getProductId());            if (vendorId.equals(TEMPERATURE_USB_VENDOR_ID) && productId.equals(TEMPERATURE_USB_PRODUCT_ID)) {                sTemperatureUsbPort = port;            }        }        if (sTemperatureUsbPort != null) {            //成功擷取連接埠，開啟串連            UsbDeviceConnection connection = mUsbManager.openDevice(sTemperatureUsbPort.getDriver().getDevice());            if (connection == null) {                Log.e(TAG, "Opening device failed");                return;            }            try {                sTemperatureUsbPort.open(connection);                //設定傳輸速率                sTemperatureUsbPort.setParameters(4800, 8, UsbSerialPort.STOPBITS_1, UsbSerialPort.PARITY_NONE);            } catch (IOException e) {                //開啟連接埠失敗，關閉！                Log.e(TAG, "Error setting up device: " + e.getMessage(), e);                try {                    sTemperatureUsbPort.close();                } catch (IOException e2) {                    // Ignore.                }                sTemperatureUsbPort = null;                return;            }        } else {            //提示未檢測到裝置        }    }    public void onDeviceStateChange() {        //重新開啟USB管理器        stopIoManager();        startIoManager();    }    private void startIoManager() {        if (sTemperatureUsbPort != null) {            Log.i(TAG, "Starting io manager ..");            mSerialIoManager = new SerialInputOutputManager(sTemperatureUsbPort, mListener);            mExecutor.submit(mSerialIoManager);  //實質是用一個線程不斷讀取USB連接埠        }    }    private void stopIoManager() {        if (mSerialIoManager != null) {            Log.i(TAG, "Stopping io manager ..");            mSerialIoManager.stop();            mSerialIoManager = null;        }    }    public void onPause() {        stopIoManager();        if (sTemperatureUsbPort != null) {            try {                sTemperatureUsbPort.close();            } catch (IOException e) {                // Ignore.            }            sTemperatureUsbPort = null;        }    }}

在Activity中使用：

    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_punch);        initUsbControl();       //初始化USB控制器    }    /**     * 初始化USB     */    private void initUsbControl() {        mTemperatureUsbControl = new TemperatureUsbControl(mContext);        mTemperatureUsbControl.initUsbControl();    }    @Override    protected void onResume() {        super.onResume();        IntentFilter usbFilter = new IntentFilter();        usbFilter.addAction(UsbManager.ACTION_USB_DEVICE_ATTACHED);        usbFilter.addAction(UsbManager.ACTION_USB_DEVICE_DETACHED);        registerReceiver(mUsbReceiver, usbFilter);        mTemperatureUsbControl.onDeviceStateChange();    }    @Override    protected void onPause() {        super.onPause();        mTemperatureUsbControl.onPause();        unregisterReceiver(mUsbReceiver);    }    /**     * 用於檢測usb插入狀態的BroadcasReceiver     */    private final BroadcastReceiver mUsbReceiver = new BroadcastReceiver() {        public void onReceive(Context context, Intent intent) {            String action = intent.getAction();            if (UsbManager.ACTION_USB_DEVICE_ATTACHED.equals(action)) {                //裝置插入                mTemperatureUsbControl.initUsbControl();                mTemperatureUsbControl.onDeviceStateChange();                Log.e(TAG, "ACTION_USB_DEVICE_ATTACHED");            } else if (UsbManager.ACTION_USB_DEVICE_DETACHED.equals(action)) {                //裝置移除                mTemperatureUsbControl.onPause();                Log.e(TAG, "ACTION_USB_DEVICE_DETACHED");            }        }    };

讀到的資料如果需要在Activity中使用，可以使用EventBus來完成~

一步一步教你簡單完成 Android USB開發