方法一、ro.build.characteristics 属性值进行判断

    public static boolean isPad() {
        boolean result = false;
        String mDeviceType = SystemPropertiesWrapper.get("ro.build.characteristics", "default");
        if (mDeviceType != null && mDeviceType.equalsIgnoreCase("tablet")) {
             result = true;
        }
        Log.d(TAG, "isPad:" + result);
        return result;
    }

实测结果

普通手机:/ # getprop ro.build.characteristics
nosdcard
普通平板:/ $ getprop ro.build.characteristics
tablet
华为手机 HWCLT:/ $ getprop ro.build.characteristics
default

方法二、屏幕尺寸大于6寸的条件

还是存在不准，有时手机还是被误判为平板

    /**
     * 判断是否为平板
     */
    public static boolean isPad(Context context) {
        boolean result = false;
        WindowManager wm = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
        Display display = wm.getDefaultDisplay();
        DisplayMetrics dm = new DisplayMetrics();
        display.getMetrics(dm);
        double x = Math.pow(dm.widthPixels / dm.xdpi, 2);
        double y = Math.pow(dm.heightPixels / dm.ydpi, 2);
        // 屏幕尺寸
        double screenInches = Math.sqrt(x + y);
        // 大于6尺寸则为Pad
        if (screenInches >= 6.0) {
            result = true;
        }
        Log.d(TAG, "isPad:" + result);
        return result;
    }

方法三、Google推荐的方法

也是不准

    public static boolean isTablet(Context context) {
        return (context.getResources().getConfiguration().screenLayout & Configuration.SCREENLAYOUT_SIZE_MASK) >= Configuration.SCREENLAYOUT_SIZE_LARGE;
    }