两步实现全面屏手机适配，虚拟导航栏的显示隐藏

1. values，values-v19,values-v21文件夹下styles添加样式，然后在AndroidManifest.xml里引用 android:theme="@style/statusBar";

//styles样式
   <!--全屏显示，有透明状态栏-->
    <style name="statusBar" parent="Theme.AppCompat.Light.NoActionBar">
        <item name="android:windowTranslucentStatus">true</item>
        <item name="android:windowTranslucentNavigation">true</item>
    </style>

2. 在BaseActivity添加以下方法，实现全面屏的效果；

  @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        getWindow().getDecorView().setSystemUiVisibility(View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN | View.SYSTEM_UI_FLAG_LIGHT_STATUS_BAR);
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
            ViewGroup rootView = (ViewGroup) this.getWindow().getDecorView().findViewById(android.R.id.content);
            rootView.setPadding(0, getStatusBarHeight(this), 0, 0);
            //判断导航栏是否存在
            if(hasNavigationBar(this)){
                //预留出状态栏和虚拟导航栏的位置
                rootView.setPadding(0, getStatusBarHeight(this), 0, getNavigationBarHeight(this));
            }
//            getWindow().setNavigationBarColor(Color.TRANSPARENT);
        } else if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
            Window window = getWindow();
            window.addFlags(WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS);
            window.addFlags(WindowManager.LayoutParams.FLAG_TRANSLUCENT_NAVIGATION);
        }  
    }



 /**
     * 获取状态栏高度
     *
     * @param context
     * @return
     */
    public static int getStatusBarHeight(Context context) {
        Resources resources = context.getResources();
        int resourceId = resources.getIdentifier("status_bar_height", "dimen", "android");
        int height = resources.getDimensionPixelSize(resourceId);
        return height;
    }

 /*
    * 判断导航栏是否存在
    * */
    public static boolean hasNavigationBar(Activity activity) {
        Point size = new Point();
        Point realSize = new Point();
        activity.getWindowManager().getDefaultDisplay().getSize(size);
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1) {
            activity.getWindowManager().getDefaultDisplay().getRealSize(realSize);
        } else {
            Display display = activity.getWindowManager().getDefaultDisplay();

            Method mGetRawH = null;
            Method mGetRawW = null;

            int realWidth = 0;
            int realHeight = 0;

            try {
                mGetRawW = Display.class.getMethod("getRawWidth");
                mGetRawH = Display.class.getMethod("getRawHeight");
            } catch (NoSuchMethodException e) {
                e.printStackTrace();
            }

            try {
                realWidth = (Integer) mGetRawW.invoke(display);
                realHeight = (Integer) mGetRawH.invoke(display);
            } catch (IllegalAccessException e) {
                e.printStackTrace();
            } catch (InvocationTargetException e) {
                e.printStackTrace();
            }
            realSize.set(realWidth, realHeight);
        }
        if (realSize.equals(size)) {
            return false;
        } else {
            size.y = size.y + getNavigationBarHeight(activity);
            if (realSize.y < size.y){
                return false;
            }
            return true;
        }
    }

  /**
     * 获取底部导航栏高度
     *
     * @return
     */
    public static int getNavigationBarHeight(Context context) {
        if(Settings.Global.getInt(context.getContentResolver(), "force_fsg_nav_bar", 0) != 0){
            //开启手势，不显示虚拟键
            return 0;
        }
        Resources resources = context.getResources();
        int resourceId = resources.getIdentifier("navigation_bar_height", "dimen", "android");
        return resources.getDimensionPixelSize(resourceId);
    }