?android:attr/selectableItemBackground (有界波纹)

?android:attr/selectableItemBackgroundBorderless (无界波纹)

 @drawable/item_background_material@drawable/item_background_borderless_material

/*** API 21* */
public class RippleDrawableActivity extends AppCompatActivity implements View.OnTouchListener{private ViewGroup buttonsContainer;private ViewGroup activeButton = null;private final int MAX_BUTTONS = 3;private class  CircleOutLineProvider extends ViewOutlineProvider{@Overridepublic void getOutline(View view, Outline outline) {outline.setOval(0,0,view.getWidth(),view.getHeight());}}@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_ripple_drawable);this.buttonsContainer = (ViewGroup) findViewById(R.id.buttonsContainer);int buttonsSpacing = (int) getResources().getDimension(R.dimen.activity_horizontal_margin);int buttonSize = (int) getResources().getDimension(R.dimen.button_size);CircleOutLineProvider circleOutLineProvider = new CircleOutLineProvider();// Outline circularOutline = new Outline();// circularOutline.setOval(0, 0, buttonSize, buttonSize);for (int i = 0; i < MAX_BUTTONS; i++) {ViewGroup buttonHost = (ViewGroup) getLayoutInflater().inflate(R.layout.circular_button_layout, buttonsContainer, false);TextView button = (TextView) buttonHost.getChildAt(0);buttonHost.setClipToOutline(true);buttonHost.setOutlineProvider(circleOutLineProvider);button.setText("Test " + i);buttonHost.setOnTouchListener(this);buttonsContainer.addView(buttonHost);//Add margin between buttons manuallyif (i != MAX_BUTTONS - 1) {buttonsContainer.addView(new Space(this), new ViewGroup.LayoutParams(buttonsSpacing, buttonSize));}}selectButton(((ViewGroup) buttonsContainer.getChildAt(0)), false);}private void selectButton(ViewGroup buttonHost, boolean reveal) {selectButton(buttonHost, reveal, buttonHost.getWidth(), buttonHost.getHeight());}private void selectButton(ViewGroup buttonHost, boolean reveal, int startX, int startY) {if (buttonHost == activeButton) {return;}if (activeButton != null) {activeButton.setSelected(false);activeButton = null;}activeButton = buttonHost;activeButton.setSelected(true);View button = activeButton.getChildAt(0);if (reveal) {//API 21ViewAnimationUtils.createCircularReveal(button,startX,startY,0,button.getHeight()).start();}}@Overridepublic boolean onTouch(View view, MotionEvent motionEvent) {switch (motionEvent.getAction()) {case MotionEvent.ACTION_DOWN:((ViewGroup) view).getChildAt(0).getBackground().setHotspot(motionEvent.getX(), motionEvent.getY());break;case MotionEvent.ACTION_UP:selectButton((ViewGroup) view, true, (int) motionEvent.getX(), (int) motionEvent.getY());break;}return false;}
}