获取屏幕尺寸

• 不包含底部虚拟按键

WindowManager windowManager = (WindowManager) getSystemService(Context.WINDOW_SERVICE);
DisplayMetrics displayMetrics = new DisplayMetrics();
windowManager.getDefaultDisplay().getMetrics(displayMetrics);
int height = displayMetrics.heightPixels;

• 包含底部虚拟按键

int height = getWindow().getDecorView().getHeight();

• 获取应用显示区域

Rect rect = new Rect();
getWindow().getDecorView().getWindowVisibleDisplayFrame(rect);

rect.top status_bar_height,即状态栏高度.
(rect.bottom - rect.top) 应用显示区域.

监听键盘状态

原理:
1.获取应用显示区域(不包含虚拟按键).
2.获取屏幕高度(不包含虚拟按键).
3.比较两者大小(正常差值为status_bar高度)
注:这种方法前提是软键盘会影响界面布局，所以需要在AndroidManifest里给activity添加android:windowSoftInputMode="adjustResize"
代码实现:

mActivityMainRootView.getViewTreeObserver().addOnGlobalLayoutListener(mOnGlobalLayoutListener);
private ViewTreeObserver.OnGlobalLayoutListener mOnGlobalLayoutListener = new ViewTreeObserver.OnGlobalLayoutListener() {
    @Override
    public void onGlobalLayout() {
        Rect rect = new Rect();
        getWindow().getDecorView().getWindowVisibleDisplayFrame(rect);
        WindowManager windowManager = (WindowManager)   getSystemService(Context.WINDOW_SERVICE);
        DisplayMetrics displayMetrics = new DisplayMetrics();
        windowManager.getDefaultDisplay().getMetrics(displayMetrics);
        int screenHeight =displayMetrics.heightPixels;        
        int heightDiff = screenHeight - (rect.bottom - rect.top);
        if (keyboardHeight == 0 && heightDiff > statusBarHeight) {
            keyboardHeight = heightDiff - statusBarHeight;
        }
        if (isShowKeyboard) {
            if (heightDiff <= statusBarHeight) {
                isShowKeyboard = false;
            }
        } else {
            if (heightDiff > statusBarHeight) {
                isShowKeyboard = true;
            }
        }
    }
};

参考链接:http://cashow.github.io/android-get-keyboard-height.html