0

我有一个一次显示一个片段的活动，现在每个片段都从服务器加载数据并继续在列表中获取数据，用户可以通过选择显示在 ActonBar 中的 Spinner 中的项目来在活动中显示另一个片段。

这是活动的代码

public class HomeActivity  extends SherlockFragmentActivity .....{

        private class ListInfo {


                private String tag;
        private Class<?> clss;
        private Bundle bundle;
        private Fragment fragment;

    public ListInfo(String tag, Class<?> clss, Bundle bundle) {
        this.tag = tag;
        this.clss = clss;
        this.bundle = bundle;
    }

}

String[] naviStrings;
private HashMap<String, ListInfo> listMap = new HashMap<String, HomeActivity.ListInfo>();

private ListInfo mLastListInfo = null;

private int currentSelectedOptionInSpinner;
ChannelFragment fr;

@SuppressWarnings("unchecked")
@Override
protected void onCreate(Bundle arg0) {
    super.onCreate(arg0);
    Log.d("HomeActivity", "onCreate");
    Log.d("onCreate bundle", "" + arg0);
    setContentView(R.layout.test);
    naviStrings = getResources().getStringArray(
            R.array.action_bar_spinner_entries);

    initializeList(arg0);

    Context context = getSupportActionBar().getThemedContext();
    ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(
            context, R.array.action_bar_spinner_entries,
            R.layout.sherlock_spinner_item);

    adapter.setDropDownViewResource(R.layout.sherlock_spinner_dropdown_item);
    getSupportActionBar().setNavigationMode(ActionBar.NAVIGATION_MODE_LIST);
    getSupportActionBar().setListNavigationCallbacks(adapter, this);
    getSupportActionBar().setSelectedNavigationItem(
            currentSelectedOptionInSpinner);

}

private void initializeList(Bundle args) {

    ListInfo listInfo = null;

    // add first Fragment

    listMap.put(naviStrings[5], (listInfo = new ListInfo(naviStrings[5],
            AboutUsActivity.class, args)));
    addFragmentToList(this, listInfo);

    listMap.put(naviStrings[3], (listInfo = new ListInfo(naviStrings[3],
            Fragment1.class, args)));
    addFragmentToList(this, listInfo);

    listMap.put(naviStrings[2], (listInfo = new ListInfo(naviStrings[2],
            Fragment2.class, args)));
    addFragmentToList(this, listInfo);

    listMap.put(naviStrings[1], (listInfo = new ListInfo(naviStrings[1],
            Fragment3.class, args)));
    addFragmentToList(this, listInfo);

    listMap.put(naviStrings[4], (listInfo = new ListInfo(naviStrings[4],
            Fragment4.class, args)));
    addFragmentToList(this, listInfo);

    if (args != null) {
        Toast.makeText(this, "args is not null", Toast.LENGTH_SHORT).show();
        // set the current selected index in the ActionBar spinner
        if (args.getInt(
                ApplicationMetaData.IntentData.LAST_SELECTED_ITEM_SPINNER,
                -1) > -1
                && args.getInt(
                        ApplicationMetaData.IntentData.LAST_SELECTED_ITEM_SPINNER,
                        -1) < naviStrings.length) {
            Toast.makeText(this, "selected  is not null",
                    Toast.LENGTH_SHORT).show();

            currentSelectedOptionInSpinner = args
                    .getInt(ApplicationMetaData.IntentData.LAST_SELECTED_ITEM_SPINNER);
        } else {
            currentSelectedOptionInSpinner = 2;
        }
    } else {
        currentSelectedOptionInSpinner = 2;
    }

    onNavigationItemSelected(currentSelectedOptionInSpinner, 0);
}

private static void addFragmentToList(SherlockFragmentActivity activity,
        ListInfo instanse) {
    // check to see if we already have a fragment for this tab , probably
    // from a previously save state.
    // if so deactivated it ,because our initial state is that a tab is not
    // shown.
    String tag = instanse.tag;

    instanse.fragment = activity.getSupportFragmentManager()
            .findFragmentByTag(tag);

    if (instanse.fragment != null && !instanse.fragment.isDetached()) {
        FragmentTransaction ft = activity.getSupportFragmentManager()
                .beginTransaction();
        ft.detach(instanse.fragment);
        ft.commit();
        activity.getSupportFragmentManager().executePendingTransactions();
    }

}



@Override
protected void onSaveInstanceState(Bundle outState) {
    super.onSaveInstanceState(outState);
    outState.putInt(
            ApplicationMetaData.IntentData.LAST_SELECTED_ITEM_SPINNER,
            currentSelectedOptionInSpinner);
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    return super.onCreateOptionsMenu(menu);
}

@Override
public boolean onNavigationItemSelected(int itemPosition, long itemId) {
    Log.d("onNavigationItemSelected", "" + itemPosition);
    if (itemPosition == 5) {
        Intent i = new Intent(this, AboutUsActivity.class);
        startActivity(i);
        return true;
    }
    Log.d("fragment data", listMap.get(naviStrings[itemPosition]) + "");
    ListInfo newtItem = listMap.get(naviStrings[itemPosition]);
    if (newtItem != mLastListInfo) {
        FragmentTransaction ft = this.getSupportFragmentManager()
                .beginTransaction();

        if (mLastListInfo != null) {
            if (mLastListInfo.fragment != null) {
                ft.detach(mLastListInfo.fragment);
            }
        }
        if (newtItem != null) {
            if (newtItem.fragment == null) {
                // create and add
                newtItem.fragment = Fragment.instantiate(this,
                        newtItem.clss.getName(), newtItem.bundle);

                ft.add(android.R.id.content, newtItem.fragment,
                        newtItem.tag);
            } else {
                ft.attach(newtItem.fragment);
            }
        }
        mLastListInfo = newtItem;
        ft.commit();
        this.getSupportFragmentManager().executePendingTransactions();
        return true;
    }

    return false;

}}

现在，当我从一个片段导航到另一个片段时，可以说从片段 1 到片段 2，当我返回片段 1 时，它会保留它的状态并且不必从头开始加载数据，但是如果我从主 Activity 启动一个新的 Activity 系统销毁 Activity 和其中的 Fragments，有没有办法在我旋转 Home Activity 时保留这些 Fragment 注释，没有发生任何事情，只有当我开始一个新的 Activity 时？？？？？？

更新 我在onCreatesetRetaineInstance(true) 中制作的所有四个片段；

4

1 回答 1

0

一种选择是在您的和/或中覆盖saveInstanceState以保留数据，然后从传递到/的数据中检索它。 FragmentsActivitesBundleonActivityCreatedonCreate

如果您正在处理大量数据，则最好使用另一种持久性机制，例如 SQLite 数据库

于 2012-09-08T14:59:40.997 回答