How to detect if Android has full USB support or n

问题:

My application uses UsbManager to communicate with USB cameras. Some devices don't have USB support. These will return null for (UsbManager)context.getSystemService( Context.USB_SERVICE ), or they will throw a NoSuchMethodError exception when enumerating devices. I can detect both and display a message properly. Unfortunately, some Androids that don't detect USB devices cause neither of these problems. They just return an empty list of USB devices. How can I properly detect that this system doesn't support USB OTG?

回答1:

The official way to determine if the device has USB host capability is to use the associated system feature.

Ideally, add a <uses-feature> element to your manifest, indicating that you are interested in the android.hardware.usb.host feature. If you do not absolutely need that feature, add android:required="false" as an attribute.

If you went with android:required="false", and you want to determine whether the device is a USB host at runtime, use PackageManager, hasSystemFeature(), and FEATURE_USB_HOST. FEATURE_USB_HOST is defined as the same string as you would be using in <uses-feature> (android.hardware.usb.host).

回答2:

public static boolean getUsbConnection(Context context) {
        intent = context.registerReceiver(null, new IntentFilter("android.hardware.usb.action.USB_STATE"));
        return intent.getExtras().getBoolean("connected");
    }