SynthesizerService.java 文件源码

@TargetApi(Build.VERSION_CODES.HONEYCOMB_MR1)
private void scanUsbMidi() {
  UsbManager usbManager = (UsbManager) getSystemService(Context.USB_SERVICE);
  HashMap<String, UsbDevice> deviceList = usbManager.getDeviceList();
  Log.i("synth", "USB device count=" + deviceList.size());
  for (UsbDevice device : deviceList.values()) {
    UsbInterface intf = UsbMidiDevice.findMidiInterface(device);
    if (intf != null) {
      if (usbManager.hasPermission(device)) {
        if (connectUsbMidi(device)) {
          break;
        }
      } else {
        usbDeviceNeedsPermission_ = device;
      }
    }
  }
}