监听键盘显示与隐藏

项目中有时候需要监听keyboard的显示与隐藏，特此备注，方便使用。

public class KeyboardWatcher {
    private ViewTreeObserver.OnGlobalLayoutListener onGlobalLayoutListener;
    private View rootView;
    private int viewSize = -1;
    private boolean isShowing = false;
    private OnKeyboardListener onKeyboardListener;
    public KeyboardWatcher(Activity activity){
        rootView = activity.getWindow().getDecorView().getRootView();
    }

    public KeyboardWatcher register(OnKeyboardListener listener){
        onKeyboardListener = listener;
        if(onGlobalLayoutListener == null) {
            onGlobalLayoutListener = new ViewTreeObserver.OnGlobalLayoutListener() {
                @Override
                public void onGlobalLayout() {
                    Rect r = new Rect();
                    rootView.getWindowVisibleDisplayFrame(r);
                    int viewHeight = r.bottom - r.top;
                    if(viewSize < 0){
                        viewSize = viewHeight;
                        return;
                    }
                    if(viewHeight != viewSize){
                        // 大于100dp才算变化
                        if(Math.abs(viewHeight - viewSize) > dpToPx(rootView.getContext(),100)) {
                            if (viewHeight < viewSize && !isShowing) {
                                onKeyboardListener.onShow(viewHeight);
                                isShowing = true;
                            } else if(isShowing){
                                onKeyboardListener.onHide();
                                isShowing = false;
                            }
                        }
                        viewSize = viewHeight;
                    }
                }
            };
        }

        rootView.post(new Runnable() {
            @Override
            public void run() {
                viewSize = rootView.getHeight();
                rootView.getViewTreeObserver().addOnGlobalLayoutListener(onGlobalLayoutListener);
            }
        });

        return this;
    }

    public void unRegister(){
        rootView.getViewTreeObserver().removeGlobalOnLayoutListener(onGlobalLayoutListener);
        rootView = null;
    }

    public interface OnKeyboardListener{

        void onShow(int viewSize);

        void onHide();

    }

    private int dpToPx(Context context,int dp) {
        return (int) TypedValue.applyDimension(
                TypedValue.COMPLEX_UNIT_DIP, dp, context.getResources().getDisplayMetrics()
        );
    }
}

使用方法

KeyBoardWatcher keyboardWatcher = new  KeyboardWatcher()
keyboardWatcher.register(this)//实现KeyboardWatcher.OnKeyboardListener接口

//实现方法onShow() , onHide(),对应键盘的显示与隐藏