How to target multiple API levels?

I am looking to use Android's Camera.open() method on two separate API levels. First is API level 7, which is 2.1 and higher and the second is 2.3.3 & 2.3.4 which are API level 9.

On API level 7 and 8 the Camera.open method does not take any arguments. On API level 9 and above, the camera takes an integer argument that supplies it the cameraId to use.

How can I target both API levels i开发者_如何学JAVAn the same code? Something similar to this pseudo code:

Camera lCamera;
if (Platform.APILevel < 7){
  lCamera.open();
}else { 
  lCamera.open(0);
}

We often do reflection detection. Something like:

    public Camera getCamera() {
        try {
            Method method = Camera.class.getMethod("open", Integer.TYPE);
            return (Camera) method.invoke(null, 0);
        } catch (Exception e) {
                // Yes, I really want to handle all exceptions here!!!!
                Log.d(TAG,"Error when trying to invoke Camera.open(int), reverting to open()",e);
                return Camera.open();
        }
    }

Generally speaking, you just target the lowest API level you can get away with. Anything built for API level 7 will work for API level 8, 9, 10, etc. In this case, just call lCamera.open(); and it will choose the first back-facing camera found. If you want to use a front camera, you have to use the higher level API level 9.

You can get the API level by reading the final static integer android.os.Build.VERSION.SDK_INT.

In your manifest, make sure that you set android:minSdkVersion AND android:targetSdkVersion.