在Activity中加入以下代码：

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {

    int flagTranslucentStatus = WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS;

    int flagTranslucentNavigation = WindowManager.LayoutParams.FLAG_TRANSLUCENT_NAVIGATION;

    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {

        Window window = getWindow();

        WindowManager.LayoutParams attributes = window.getAttributes();

        attributes.flags |= flagTranslucentNavigation;

        window.setAttributes(attributes);

        getWindow().setStatusBarColor(Color.TRANSPARENT);

    } else {

        Window window = getWindow();

        WindowManager.LayoutParams attributes = window.getAttributes();

        attributes.flags |= flagTranslucentStatus | flagTranslucentNavigation;

        window.setAttributes(attributes);

    }

}