Android System UI visibility

1.首先UI Visibility Flag分为：

    /*View has requested the system UI (status bar) to be visible (the default).*/
1.View.SYSTEM_UI_FLAG_VISIBLE;
   /*View has requested the system UI to enter an unobtrusive "low profile" mode.*/
2.View.SYSTEM_UI_FLAG_LOW_PROFILE;
    /*View has requested to go into the normal fullscreen mode so that its content can take             
     *over the screen while still allowing the user to interact with the application.
     */
3.View.SYSTEM_UI_FLAG_FULLSCREEN;
    /*View has requested that the system navigation be temporarily hidden.*/
4.View.SYSTEM_UI_FLAG_HIDE_NAVIGATION;
    /* Flag for {@link #setSystemUiVisibility(int)}: When using other layout
     * flags, we would like a stable view of the content insets given to
     * {@link #fitSystemWindows(Rect)}.  This means that the insets seen there
     * will always represent the worst case that the application can expect
     * as a continuous state.  In the stock Android UI this is the space for
     * the system bar, nav bar, and status bar, but not more transient elements
     * such as an input method.
     */
5.View.SYSTEM_UI_FLAG_LAYOUT_STABLE;
   /* Flag for {@link #setSystemUiVisibility(int)}: View would like its window to be laid out as if it  has requested */
6.View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION;
    /**
     * Flag for {@link #setSystemUiVisibility(int)}: View would like its window
     * to be laid out as if it has requested
     * {@link #SYSTEM_UI_FLAG_FULLSCREEN}, even if it currently hasn't.  This
     * allows it to avoid artifacts when switching in and out of that mode, at
     * the expense that some of its user interface may be covered by screen
     * decorations when they are shown.  You can perform layout of your inner
     * UI elements to account for non-fullscreen system UI through the
     * {@link #fitSystemWindows(Rect)} method.*/
7.View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN;
   /**
     * Flag for {@link #setSystemUiVisibility(int)}: View would like to remain interactive when
     * hiding the navigation bar with {@link #SYSTEM_UI_FLAG_HIDE_NAVIGATION}.  If this flag is
     * not set, {@link #SYSTEM_UI_FLAG_HIDE_NAVIGATION} will be force cleared by the system on any
     * user interaction.
     * <p>Since this flag is a modifier for {@link #SYSTEM_UI_FLAG_HIDE_NAVIGATION}, it only has an effect when used in combination with that flag.</p>
     */
8.View.SYSTEM_UI_FLAG_IMMERSIVE;
 /**
     * Flag for {@link #setSystemUiVisibility(int)}: View would like to remain interactive when
     * hiding the status bar with {@link #SYSTEM_UI_FLAG_FULLSCREEN} and/or hiding the navigation
     * bar with {@link #SYSTEM_UI_FLAG_HIDE_NAVIGATION}.  Use this flag to create an immersive
     * experience while also hiding the system bars.  If this flag is not set,
     * {@link #SYSTEM_UI_FLAG_HIDE_NAVIGATION} will be force cleared by the system on any user
     * interaction, and {@link #SYSTEM_UI_FLAG_FULLSCREEN} will be force-cleared by the system
     * if the user swipes from the top of the screen.
     * <p>When system bars are hidden in immersive mode, they can be revealed temporarily with
     * system gestures, such as swiping from the top of the screen.  These transient system bars
     * will overlay app’s content, may have some degree of transparency, and will automatically
     * hide after a short timeout.
     * </p><p>Since this flag is a modifier for {@link #SYSTEM_UI_FLAG_FULLSCREEN} and
     * {@link #SYSTEM_UI_FLAG_HIDE_NAVIGATION}, it only has an effect when used in combination
     * with one or both of those flags.</p>
     */
9.View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY;
 /** Flag for {@link #setSystemUiVisibility(int)}: Requests the status bar to draw in a mode that  is compatible with light status bar backgrounds.*/
10.View.SYSTEM_UI_FLAG_LIGHT_STATUS_BAR;

2.分类看效果

 View decorView = getWindow().getDecorView();
        //statusbar 部分图标会直接变为灰点，但是在国内手机无效，google亲儿子上有效
        //decorView.setSystemUiVisibility(View.SYSTEM_UI_FLAG_LOW_PROFILE);
        //statusbar消失，页面布局占据statusbar区域，但是下拉显示通知的时候，statusbar会出现，也就是这个flag会失效，同时由于statusbar的出现，会导致界面跳动
//        decorView.setSystemUiVisibility(View.SYSTEM_UI_FLAG_FULLSCREEN);
        //navigationbar会消失，同时，页面布局会占据navigationbar的位置，同时，在与界面产生交互（比如touch下界面，即使没有设置touch回调），flag会失效，同时navigationbar就会显示，界面同样会跳动
//        decorView.setSystemUiVisibility(View.SYSTEM_UI_FLAG_HIDE_NAVIGATION);
        //statusbar+navigationbar消失，同时页面布局占据二者位置，同时，在与界面产生交互（比如touch下界面，即使没有设置touch回调），flag会失效，同时navigationbar+statusbar会显示，界面同样会跳动
//        decorView.setSystemUiVisibility(View.SYSTEM_UI_FLAG_FULLSCREEN|View.SYSTEM_UI_FLAG_HIDE_NAVIGATION);
        //单独使用无任何效果，需要配合fullscreen||hide_navigation等使用
//        decorView.setSystemUiVisibility(View.SYSTEM_UI_FLAG_LAYOUT_STABLE);
        //单独使用，没看到效果（target：16）
//        decorView.setSystemUiVisibility(View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION);
        //statusbar+navigationbar均没有变化，但是，应用的布局会上顶，部分会被statusbar覆盖
//        decorView.setSystemUiVisibility(View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN);
        //单独使用没看到效果（target：19）
//        decorView.setSystemUiVisibility(View.SYSTEM_UI_FLAG_IMMERSIVE);
        //单独使用没看到效果（target：19）
//        decorView.setSystemUiVisibility(View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY);
        //statusbar的字体颜色会由白色（默认）变为黑色
        decorView.setSystemUiVisibility(View.SYSTEM_UI_FLAG_LIGHT_STATUS_BAR);

3.沉浸式状态栏/透明状态栏

简而言之就是：
1.沉浸式：应用中不应该看到状态栏/导航栏，这种效果在应用中比较少见，一般用在游戏中
2.透明：状态栏透明，颜色字体由具体应用指定