Android独立于Activity或者Fragment的LoadingDialog的实现

public class LoadDialogMgr {

  private static final String LOAD_TIP_DIALOG_TAG = "LoadTipDialog";
  private static LoadDialogMgr sMLoadDialogMgr;

  private LoadDialogMgr() {
  }

  public static LoadDialogMgr instance() {
    if (sMLoadDialogMgr == null) {
      sMLoadDialogMgr = new LoadDialogMgr();
    }
    return sMLoadDialogMgr;
  }

  public void showDialog(FragmentActivity activity) {
    FragmentManager manager = activity.getSupportFragmentManager();
    LoadTipDialog loadTipDialog;
    Fragment fragment = manager.findFragmentByTag(LOAD_TIP_DIALOG_TAG);
    if (fragment instanceof LoadTipDialog) {
      loadTipDialog = (LoadTipDialog) fragment;
    } else {
      loadTipDialog = LoadTipDialog.newInstance();
    }
    if (loadTipDialog.isAdded()) {
      return;
    }
    manager.beginTransaction()
        .remove(loadTipDialog)
        .add(loadTipDialog, LOAD_TIP_DIALOG_TAG)
        .commitAllowingStateLoss();
  }

  public void closeDialog(FragmentActivity activity) {
    FragmentManager manager = activity.getSupportFragmentManager();
    LoadTipDialog loadTipDialog;
    Fragment fragment = manager.findFragmentByTag(LOAD_TIP_DIALOG_TAG);
    if (fragment instanceof LoadTipDialog) {
      loadTipDialog = (LoadTipDialog) fragment;
      loadTipDialog.dismissAllowingStateLoss();
    }
  }

  public void showDialog() {
    Activity activity = ActivityUtil.getTopActivity();
    if (activity instanceof FragmentActivity) {
      showDialog((FragmentActivity) activity);
    }
  }

  public void closeDialog() {
    Activity activity = ActivityUtil.getTopActivity();
    if (activity instanceof FragmentActivity) {
      closeDialog((FragmentActivity) activity);
    }
  }

}

public class LoadTipDialog extends AppCompatDialogFragment {

  private View mRootView;

  public static LoadTipDialog newInstance() {
    Bundle args = new Bundle();
    LoadTipDialog fragment = new LoadTipDialog();
    fragment.setArguments(args);
    return fragment;
  }

  @Nullable
  @Override
  public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container,
      @Nullable Bundle savedInstanceState) {
    mRootView = inflater.inflate(R.layout.dialog_load_tip, container, false);
    return mRootView;
  }
}

//R.layout.dialog_load_tip
<?xml version="1.0> encoding="utf-8"?>
<LinearLayout
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:layout_gravity="center"
  android:padding="15dp"
  android:background="#999999"
  android:gravity="center"
  android:orientation="vertical">
  <ProgressBar
    android:id="@+id/progress_bar"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"/>
  <TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:paddingTop="10dp"
    android:text="   loading..."
    android:textColor="@color/black"
    android:textSize="16sp"/>
</LinearLayout>