手机屏幕尺寸怎么量 Android APP适配全面屏手机的技术要点(5)

其实，假如我们能够获取系统服务WindowManagerService在应用进程的代理的话，直接调用其hasNavigationBar方法来判断，是不是会更简单呢？但问题是如何获取WindowManagerService在应用进程的代理呢？

查阅源码，我们发现，android.view.WindowManagerGlobal中有一个静态方法就是获取WindowManagerService在本地的代理实现：

    public static IWindowManager getWindowManagerService() {
        synchronized (WindowManagerGlobal.class) {
            if (sWindowManagerService == null) {
                sWindowManagerService = IWindowManager.Stub.asInterface(
                        ServiceManager.getService("window"));
                try {
                    if (sWindowManagerService != null) {
                        ValueAnimator.setDurationScale(
                                sWindowManagerService.getCurrentAnimatorScale());
                    }
                } catch (RemoteException e) {
                    throw e.rethrowFromSystemServer();
                }
            }
            return sWindowManagerService;
        }
    }

因此，我们可以通过反射调用此方法获取IWindowManager，再调用IWindowManager的hasNavigationBar方法来判断NavigationBar存在与否，具体请看代码：

    /**
     * 判断设备是否存在NavigationBar
     *
     * @return true 存在, false 不存在
     */
    public static boolean deviceHasNavigationBar() {
        boolean haveNav = false;
        try {
            //1.通过WindowManagerGlobal获取windowManagerService
            // 反射方法：IWindowManager windowManagerService = WindowManagerGlobal.getWindowManagerService();
            Class<?> windowManagerGlobalClass = Class.forName("android.view.WindowManagerGlobal");
            Method getWmServiceMethod = windowManagerGlobalClass.getDeclaredMethod("getWindowManagerService");
            getWmServiceMethod.setAccessible(true);
            //getWindowManagerService是静态方法，所以invoke null
            Object iWindowManager = getWmServiceMethod.invoke(null);  

            //2.获取windowMangerService的hasNavigationBar方法返回值
            // 反射方法：haveNav = windowManagerService.hasNavigationBar();
            Class<?> iWindowManagerClass = iWindowManager.getClass();
            Method hasNavBarMethod = iWindowManagerClass.getDeclaredMethod("hasNavigationBar");
            hasNavBarMethod.setAccessible(true);
            haveNav = (Boolean) hasNavBarMethod.invoke(iWindowManager);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return haveNav;
    }

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