项目中有一个新的需求，要求可以连接一个USB体温枪，APP可以从体温枪中读取到体温数据，一番搜寻之后发现一个封装很棒的USB通信库。
github地址：usb-serial-for-android
准备工作
- 从 github 上 clone 这个库的源文件
-
在Android Studio中引入模块
-
在build.gradle中添加依赖
compile project(path: ':usbSerialForAndroid') -
复制 device_filter.xml 到项目的 res/xml/ 文件夹下
-
配置 AndroidManifest.xml 文件
<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
示例代码解析：
// 获取系统服务得到UsbManager实例
UsbManager manager = (UsbManager) getSystemService(Context.USB_SERVICE);
//查找所有插入的设备
List<UsbSerialDriver> availableDrivers = UsbSerialProber.getDefaultProber().findAllDrivers(manager);
if (availableDrivers.isEmpty()) {
return;
}
// 打开设备，建立通信连接
UsbSerialDriver driver = availableDrivers.get(0);
UsbDeviceConnection connection = manager.openDevice(driver.getDevice());
if (connection == null) {
// You probably need to call UsbManager.requestPermission(driver.getDevice(), ..)
return;
}
//打开端口，设置端口参数，读取数据
UsbSerialPort port = driver.getPorts().get(0);
try {
port.open(connection);
//四个参数分别是：波特率，数据位，停止位，校验位
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();
}上述代码是库作者写的一段示例代码，可以看出使用上非常简单，下面的代码演示了如何将USB操作都封装到一个类里。
public class TemperatureUsbControl {
private static final String TAG = TemperatureUsbControl.class.getSimpleName();
private static final String TEMPERATURE_USB_VENDOR_ID = "067B"; //供应商id
private static final String TEMPERATURE_USB_PRODUCT_ID = "2303"; //产品id
private Context mContext;
private UsbManager mUsbManager; //USB管理器
private UsbSerialPort sTemperatureUsbPort = null; //接体温枪的usb端口
private SerialInputOutputManager mSerialIoManager; //输入输出管理器（本质是一个Runnable）
private final ExecutorService mExecutor = Executors.newSingleThreadExecutor(); //用于不断从端口读取数据
//数据输入输出监听器
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);
//全部设备
List<UsbSerialDriver> usbSerialDrivers = UsbSerialProber.getDefaultProber().findAllDrivers(mUsbManager);
//全部端口
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;
//校验设备，设备是 2303设备
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) {
//成功获取端口，打开连接
UsbDeviceConnection connection = mUsbManager.openDevice(sTemperatureUsbPort.getDriver().getDevice());
if (connection == null) {
Log.e(TAG, "Opening device failed");
return;
}
try {
sTemperatureUsbPort.open(connection);
//设置波特率
sTemperatureUsbPort.setParameters(4800, 8, UsbSerialPort.STOPBITS_1, UsbSerialPort.PARITY_NONE);
} catch (IOException e) {
//打开端口失败，关闭！
Log.e(TAG, "Error setting up device: " + e.getMessage(), e);
try {
sTemperatureUsbPort.close();
} catch (IOException e2) {
// Ignore.
}
sTemperatureUsbPort = null;
return;
}
} else {
//提示未检测到设备
}
}
public void onDeviceStateChange() {
//重新开启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); //实质是用一个线程不断读取USB端口
}
}
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);
}
/**
* 用于检测usb插入状态的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)) {
//设备插入
mTemperatureUsbControl.initUsbControl();
mTemperatureUsbControl.onDeviceStateChange();
Log.e(TAG, "ACTION_USB_DEVICE_ATTACHED");
} else if (UsbManager.ACTION_USB_DEVICE_DETACHED.equals(action)) {
//设备移除
mTemperatureUsbControl.onPause();
Log.e(TAG, "ACTION_USB_DEVICE_DETACHED");
}
}
};读到的数据如果需要在Activity中使用，可以使用EventBus来完成~