activity在豎屏的時候，頂部會有狀態列，頂部會有ToolBar，現在需求是，旋轉螢幕以後，橫屏狀態下 整個介面是以全屏狀態顯示，隱藏ToolBar，不顯示螢幕最頂部的狀態列

首先，在AndroidManiFest裡面設定Activity的屬性：

<activity
android:name=".MainActivity"
android:configChanges="keyboardHidden|orientation|screenSize"
android:screenOrientation="sensor"
    />

然後，在Activity中重寫onConfigurationChanged方法，程式碼如下：

private boolean portrait;
@Override
public void onConfigurationChanged(Configuration newConfig) {
    super.onConfigurationChanged(newConfig);
portrait = newConfig.orientation == Configuration.ORIENTATION_PORTRAIT;
tryFullScreen(!portrait);
}

private void tryFullScreen(boolean fullScreen) {
    if 
 
(activity instanceof AppCompatActivity) {
        ActionBar supportActionBar = ((AppCompatActivity) activity).getSupportActionBar();
        if (supportActionBar != null) {
            if (fullScreen) {
                supportActionBar.hide();
} else {
                supportActionBar.show();
}
        }
    }
    setFullScreen(fullScreen);
 
}


private void setFullScreen(boolean fullScreen) {
        WindowManager.LayoutParams attrs = getWindow().getAttributes();
        if (fullScreen) {
            attrs.flags |= WindowManager.LayoutParams.FLAG_FULLSCREEN;
getWindow().setAttributes(attrs);
getWindow().addFlags(WindowManager.LayoutParams.FLAG_LAYOUT_NO_LIMITS);
} else {
            attrs.flags &= (~WindowManager.LayoutParams.FLAG_FULLSCREEN);
getWindow().setAttributes(attrs);
getWindow().clearFlags(WindowManager.LayoutParams.FLAG_LAYOUT_NO_LIMITS);
}

}