<style name="FullScreenDialogTheme" parent="Theme.AppCompat.Dialog">
      <!-- 上面说过，只要是Dialog，这两个属性必须设置 -->
      <item name="android:windowIsFloating">false</item>
      <item name="android:windowBackground">@android:color/transparent</item>
      <!--设置透明状态栏，适用于SDK19（4.4）及以上版本-->
      <item name="android:windowTranslucentStatus" >true</item>
      <!-- 如果你不需要自定义状态栏颜色，下面两个可不要 -->
      <item name="android:windowDrawsSystemBarBackgrounds" >true</item>
      <item name="android:statusBarColor">@android:color/transparent</item>
      <!-- 透明导航栏 -->
      <item name="android:windowTranslucentNavigation">true</item>
  </style>

public class FullPhotoDialog extends DialogFragment {

  @NonNull
  @NotNull
  @Override
  public Dialog onCreateDialog(@Nullable @org.jetbrains.annotations.Nullable Bundle savedInstanceState) {
      setStyle(STYLE_NORMAL, R.style.FullScreenDialogTheme);
      Dialog dialog = super.onCreateDialog(savedInstanceState);
      Window window = dialog.getWindow();
      window.clearFlags(WindowManager.LayoutParams.FLAG_DIM_BEHIND);
      window.setBackgroundDrawable(new ColorDrawable(Color.TRANSPARENT));
      window.getDecorView().setPadding(0, 0, 0, 0);
      WindowManager.LayoutParams layoutParams = window.getAttributes();
      layoutParams.width = WindowManager.LayoutParams.MATCH_PARENT;
      layoutParams.height = WindowManager.LayoutParams.MATCH_PARENT;
      return dialog;
  }
}