使用Android Studio(当前版本是2.2.2)很容易添加一个全屏活动。

请看步骤:

右键单击你的java主包，选择“新建”，选择“活动”，然后点击“全屏活动”。

自定义活动(“活动名称”，“布局名称”等)，点击“完成”。

完成了!

现在你有一个全屏的活动很容易(查看java类和活动布局，以了解事情是如何工作的)!

谢谢你的回答@克里斯蒂安，我得到了错误

android.util.AndroidRuntimeException:必须调用requestFeature() 添加内容前

我用

@Override
protected void onCreate(Bundle savedInstanceState) {

    requestWindowFeature(Window.FEATURE_NO_TITLE);

    super.onCreate(savedInstanceState);

    getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);

    setContentView(R.layout.activity_login);

    -----
    -----
}

提示:使用getWindow().setLayout()会搞砸你的全屏显示!注意，这个方法的文档说:

设置窗口的宽度和高度布局参数… 你可以把它们改成……用于制作非全屏窗口的绝对值。

http://developer.android.com/reference/android/view/Window.html#setLayout%28int,%20int%29

For my purposes, I found that I had to use setLayout with absolute parameters to resize my full screen window correctly. Most of the time, this worked fine. It was called by an onConfigurationChanged() event. There was a hiccup, however. If the user exited the app, changed the orientation, and reentered, it would lead to firing off my code which included setLayout(). During this re-entry time window, my status bar (which was hidden by the manifest) would be made to re-appear, but at any other time setLayout() would not cause this! The solution was to add an additional setLayout() call after the one with the hard values like so:

       public static void setSize( final int width, final int height ){
//DO SOME OTHER STUFF...
            instance_.getWindow().setLayout( width, height );
            // Prevent status bar re-appearance
            Handler delay = new Handler();
            delay.postDelayed( new Runnable(){ public void run() {
                instance_.getWindow().setLayout(
                    WindowManager.LayoutParams.FILL_PARENT,
                    WindowManager.LayoutParams.FILL_PARENT );
            }}, FILL_PARENT_ON_RESIZE_DELAY_MILLIS );
        }

然后，窗口正确地调整大小，状态栏不会重新出现，不管触发这一事件。

import androidx.core.view.WindowInsetsCompat.Type

fun Activity.fullscreen() {
    with(WindowInsetsControllerCompat(window, window.decorView)) {
        systemBarsBehavior = WindowInsetsControllerCompat.BEHAVIOR_SHOW_BARS_BY_SWIPE
        hide(Type.systemBars())
    }
}

fun Activity.exitFullscreen() {
    WindowInsetsControllerCompat(window, window.decorView).show(Type.systemBars())
}

通过缺口或切口区域显示内容。这可以从文档中得到帮助:

LAYOUT_IN_DISPLAY_CUTOUT_MODE_SHORT_EDGES -在纵向和横向模式下将内容呈现到剪切区域。

对我来说最重要的是activity样式中的这一行:

// Important to draw through the cutouts
<item name="android:windowLayoutInDisplayCutoutMode">shortEdges</item> 

对我来说，我想以沉浸式模式展示图像。当我点击它时，我希望系统UI(状态和导航栏)显示出来。

以下是我的解决方案:

在Activity中，一些显示/隐藏系统UI的方法(状态条/导航条)

private fun hideSystemUI() {
    sysUIHidden = true
    window.decorView.systemUiVisibility = (
            View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY
            or View.SYSTEM_UI_FLAG_LAYOUT_STABLE 
            // Hide the nav bar and status bar
            or View.SYSTEM_UI_FLAG_HIDE_NAVIGATION // Hide nav bar
            or View.SYSTEM_UI_FLAG_FULLSCREEN // Hide status bar
            )
}


private fun showSystemUI() {
    sysUIHidden = false
    window.decorView.systemUiVisibility = (
            View.SYSTEM_UI_FLAG_LAYOUT_STABLE
            // Set the content to appear under the system bars so that the
            // content doesn't resize when the system bars hide and show.
            or View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION // layout Behind nav bar
            or View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN // layout Behind status bar
            )
}

2-确保在你的xml布局的根视图中

android:fitsSystemWindows="false"

3-全屏活动的风格将给状态/导航栏显示时一个半透明的背景:

<style name="FullscreenTheme" parent="AppTheme">
    <item name="android:actionBarStyle">@style/FullscreenActionBarStyle</item>
    <item name="android:windowActionBarOverlay">true</item>
    <item name="android:windowBackground">@null</item>
    <item name="metaButtonBarStyle">?android:attr/buttonBarStyle</item>
    <item name="metaButtonBarButtonStyle">?android:attr/buttonBarButtonStyle</item>
    <item name="android:statusBarColor">#50000000</item>
    <item name="android:navigationBarColor">#50000000</item>
    // Important to draw behind cutouts
    <item name="android:windowLayoutInDisplayCutoutMode">shortEdges</item> 
</style>

<style name="FullscreenActionBarStyle" parent="Widget.AppCompat.ActionBar">
    <item name="android:background">@color/sysTransparent</item>
</style>

这些答案大部分似乎都过时了。Developer.android.com建议这样做:

科特林：

private fun hideSystemBars() {
    val windowInsetsController = ViewCompat.getWindowInsetsController(window.decorView) ?: return
    windowInsetsController.systemBarsBehavior = WindowInsetsControllerCompat.BEHAVIOR_SHOW_TRANSIENT_BARS_BY_SWIPE
    windowInsetsController.hide(WindowInsetsCompat.Type.systemBars())
}

Java:

private void hideSystemBars() {
    WindowInsetsControllerCompat windowInsetsController = ViewCompat.getWindowInsetsController(getWindow().getDecorView());
    if (windowInsetsController == null) {
        return;
    }
    windowInsetsController.setSystemBarsBehavior(WindowInsetsControllerCompat.BEHAVIOR_SHOW_TRANSIENT_BARS_BY_SWIPE);
    windowInsetsController.hide(WindowInsetsCompat.Type.systemBars());
}

更多信息:https://developer.android.com/training/system-ui/immersive