陷入从活动到片段的移植 [英] Stuck with porting from activity to fragment

问题描述

现在恰好一个星期，我试图将一个基于活动的简单应用移植到片段上.我完全被困住了.

It's now one week exactly that I try to port a simple activity-based app to fragments. I'm totally stuck.

这只野兽是一个带有上下文菜单和选项菜单的简单列表，详细信息，添加/编辑应用程序.我试图做到这一点:使用电话和平板电脑的v4支持程序包，将片段和活动分别保存在自己的文件中，片段完成可重用片段应做的所有工作，并且回调(很多)回荡以通知活动并有关做什么的片段.从SQLiteOpenHelper转换为ContentProvider，从optionmenu转换为actionbarmenu，以及and和and ...(现在已弃用几乎所有我使用的东西).

This beast is a simple List, Details, Add/Edit app with contextmenu and optionmenus. I tried to make it right: Fragments and activities each in their own file, using the v4 support-package for phone and tablet, fragments do everything a re-usable fragment should do and callbacks (lots of them) fly around to inform activities and fragments about what to do. Converting from SQLiteOpenHelper to ContentProvider, converting from optionmenu to actionbarmenu, and, and, and, ... (nearly everything I used is deprecated now).

太可怕了.我的基于工作活动的简单小型应用程序现在的大小几乎是其三倍，并且许多功能尚无法正常工作.

It's horrible. My simple and small working activity-based app has nearly 3 times the size now and lots of things are not working yet.

如果需要，我可以在这里添加我的代码-但这很多东西(您已经被警告过).

If it's required I can add my code here - but it's a lot of stuff (you've been warned).

我的问题:是否有人愿意与列表，详细信息 AND 添加/编辑共享完整的示例?此示例应为片段和活动"使用单独的文件(而不是Google的多合一程序包).

My question: Is there somebody willing to share a complete example with List, Details AND Add/Edit? This example should use seperate files for Fragments and Activities (not that all-in-one package from Google).

请不要拒绝投票.我真的很想看看如何做对.

Please don't down-vote. I really would like to see how to make it right.

非常感谢.

这是开始活动，它具有两种布局(电话的res/layout和平板电脑的res/layout-large-land)和上下文菜单:

Here's the starting activity with it's two layouts (res/layout for phone and res/layout-large-land for tablets) and the contextmenu:

public class ActivityList extends FragmentActivity implements FragmentList.MyContextItemSelectedListener,
                                                      FragmentList.MyDeleteListener,
                                                      FragmentList.MyListItemClickListener,
                                                      FragmentList.MyOptionsItemSelectedListener,
                                                      FragmentDetails.MyDeleteListener,
                                                      FragmentDetails.MyOptionsItemSelectedListener {

    @Override
    public void myContextItemSelected(final int action, final long id) {
        if (action == R.id.men_add) {
            processEdit(0);
        } else if (action == R.id.men_delete) {
            processUpdateList();
        } else if (action == R.id.men_details) {
            processDetails(id);
        } else if (action == R.id.men_edit) {
            processEdit(id);
        }
    }

    @Override
    public void myDelete(final long id) {
        processUpdateList();
    }

    @Override
    public void myListItemClick(final long id) {
        processDetails(id);
    }

    @Override
    public void myOptionsItemSelected(final int action) {
        myOptionsItemSelected(action, 0);
    }

    @Override
    public void myOptionsItemSelected(final int action, final long id) {
        if (action == R.id.men_add) {
            processEdit(0);
        } else if (action == R.id.men_edit) {
            processEdit(id);
        } else if (action == R.id.men_preferences) {
            processPreferences();
        }
    }

    @Override
    protected void onActivityResult(final int requestCode, final int resultCode, final Intent intent) {
        processUpdateList();
    }

    @Override
    public void onCreate(final Bundle bundle) {
        super.onCreate(bundle);

        setContentView(R.layout.activitylist);
    }

    private void processEdit(final long id) {
        Intent intent = new Intent(this, ActivityEdit.class);
        intent.putExtra("ID", id);
        startActivityForResult(intent, MyConstants.DLG_TABLE1EDIT);
    }

    private void processDetails(final long id) {
        if (Tools.isXlargeLand(getApplicationContext())) {
            Fragment fragment = getSupportFragmentManager().findFragmentById(R.id.right);
            if (fragment == null ||
                    (fragment instanceof FragmentDetails && ((FragmentDetails) fragment).getCurrentId() != id)) {
                fragment = new FragmentDetails(id);

                FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
                transaction.replace(R.id.right, fragment);
                transaction.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE);
                transaction.commit();
            }
        } else {
            Intent intent = new Intent(this, ActivityDetails.class);
            intent.putExtra("ID", id);
            startActivityForResult(intent, MyConstants.DLG_TABLE1SHOW);
        }
    }

    private void processPreferences() {
        Intent intent = new Intent(this, MyPreferenceActivity.class);
        startActivityForResult(intent, MyConstants.DLG_PREFERENCES);
    }

    private void processUpdateList() {
        // TODO:
    }
}

<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="horizontal" >

    <fragment 
        class="com.test.app.FragmentList"
        android:id="@+id/fragmentlist"
        android:layout_height="match_parent"
        android:layout_width="match_parent"
        android:name="com.test.app.FragmentList" />
</LinearLayout>

<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="horizontal" >

    <fragment 
        class="com.test.app.FragmentList"
        android:id="@+id/fragmentlist"
        android:layout_height="match_parent"
        android:layout_weight="1"
        android:layout_width="0dip"
        android:name="com.test.app.FragmentList" />

    <FrameLayout
        android:id="@+id/right"
        android:layout_height="match_parent"
        android:layout_weight="2"
        android:layout_width="0dip" />
</LinearLayout>

这是具有行布局，选项菜单和上下文菜单的ListFragment:

Here's the ListFragment with it's row layout, optionsmenu and contextmenu:

public class FragmentList extends ListFragment implements LoaderManager.LoaderCallbacks<Cursor> {

    private SimpleCursorAdapter           adapter;
    private AlertDialog                   alertDialog;
    private Context                       context;
    private MyContextItemSelectedListener contextItemSelectedListener;
    private MyDeleteListener              deleteListener;
    private long                          id;
    private MyListItemClickListener       listItemClickListener;
    private ListView                      listView;
    private MyOptionsItemSelectedListener optionsItemSelectedListener;

    public interface MyContextItemSelectedListener {
        public void myContextItemSelected(int action, long id);
    }

    public interface MyDeleteListener {
        public void myDelete(long id);
    }

    public interface MyListItemClickListener {
        public void myListItemClick(long id);
    }

    public interface MyOptionsItemSelectedListener {
        public void myOptionsItemSelected(int action);
    }

    @Override
    public void onActivityCreated(final Bundle bundle) {
        super.onActivityCreated(bundle);

        context = getActivity().getApplicationContext();

        listView = getListView();

        getActivity().getSupportLoaderManager().initLoader(MyConstants.LDR_TABLE1LIST, null, this);

        adapter = new SimpleCursorAdapter(context,
                                          R.layout.fragmentlist_row,
                                          null,
                                          new String[] { Table1.DESCRIPTION },
                                          new int[] { R.id.fragmentlist_row_description },
                                          CursorAdapter.FLAG_REGISTER_CONTENT_OBSERVER);
        setListAdapter(adapter);
        setListShown(false);

        registerForContextMenu(listView);

        if (bundle != null && bundle.containsKey("ID")) {
            id = bundle.getLong("ID");
            listItemClickListener.myListItemClick(id);
        }

        if (Tools.isXlargeLand(context)) {
            listView.setChoiceMode(ListView.CHOICE_MODE_SINGLE);
        }

        setHasOptionsMenu(true);
    }

    @Override
    public void onAttach(final Activity activity) {
        super.onAttach(activity);

        // Reduced: Check for implemented listeners
    }

    @Override
    public boolean onContextItemSelected(final MenuItem menuItem) {
        AdapterContextMenuInfo adapterContextMenuInfo = (AdapterView.AdapterContextMenuInfo) menuItem.getMenuInfo();

        final long id = adapterContextMenuInfo.id;

        if (menuItem.getItemId() == R.id.men_delete) {
            processAlertDialog(id);
            return true;
        } else {
            contextItemSelectedListener.myContextItemSelected(menuItem.getItemId(), adapterContextMenuInfo.id);
        }

        return super.onContextItemSelected(menuItem);
    }

    @Override
    public void onCreateContextMenu(final ContextMenu contextMenu, final View view, final ContextMenuInfo contextMenuInfo) {
        super.onCreateContextMenu(contextMenu, view, contextMenuInfo);

        if (view.getId() == android.R.id.list) {
            getActivity().getMenuInflater().inflate(R.menu.fragmentlist_context, contextMenu);
        }
    }

    @Override
    public Loader<Cursor> onCreateLoader(final int id, final Bundle bundle) {
        MyCursorLoader loader = null;

        switch (id) {
            case MyConstants.LDR_TABLE1LIST:
                loader = new MyCursorLoader(context,
                                            MySQLiteOpenHelper.TABLE1_FETCH,
                                            null);
                break;
        }

        return loader;
    }

    @Override
    public void onCreateOptionsMenu(final Menu menu, final MenuInflater menuInflater) {
        super.onCreateOptionsMenu(menu, menuInflater);

        menu.clear();

        menuInflater.inflate(R.menu.fragmentlist, menu);
    }

    @Override
    public void onListItemClick(final ListView listView, final View view, final int position, final long id) {
        super.onListItemClick(listView, view, position, id);

        this.id = id;

        if (Tools.isXlargeLand(context)) {
            listView.setItemChecked(position, true);
        }

        listItemClickListener.myListItemClick(id);
    }

    @Override
    public void onLoaderReset(final Loader<Cursor> loader) {
        adapter.swapCursor(null);
    }

    @Override
    public void onLoadFinished(final Loader<Cursor> loader, final Cursor cursor) {
        adapter.swapCursor(cursor);

        setListShown(true);
    }

    @Override
    public boolean onOptionsItemSelected(final MenuItem menuItem) {
        optionsItemSelectedListener.myOptionsItemSelected(menuItem.getItemId());

        return super.onOptionsItemSelected(menuItem);
    }

    @Override
    public void onSaveInstanceState(final Bundle bundle) {
        super.onSaveInstanceState(bundle);

        bundle.putLong("ID", id);
    }

    private void processAlertDialog(final long id) {
        final AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(getActivity());
        alertDialogBuilder.setNegativeButton(android.R.string.cancel, new DialogInterface.OnClickListener() {

            @Override
            public void onClick(final DialogInterface dialogInterface, final int which) {
                dialogInterface.dismiss();
            }
        } );
        alertDialogBuilder.setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {

            @Override
            public void onClick(final DialogInterface dialogInterface, final int which) {
                MyApplication.getSqliteOpenHelper().deleteTable1(id);

                alertDialog.dismiss();

                deleteListener.myDelete(id);
            }
        } );
        alertDialogBuilder.setCancelable(false);
        alertDialogBuilder.setMessage(R.string.txt_reallydelete);

        alertDialog = alertDialogBuilder.create();
        alertDialog.show();
    }
}

<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_height="wrap_content"
    android:layout_width="fill_parent"
    android:orientation="horizontal"
    android:paddingBottom="2dip"
    android:paddingTop="2dip" >

    <TextView
        style="@style/TextViewLarge"
        android:id="@+id/fragmentlist_row_description"
        android:textStyle="bold" />
</LinearLayout>


<menu
    xmlns:android="http://schemas.android.com/apk/res/android">

    <item
        android:icon="@drawable/ic_menu_add"
        android:id="@+id/men_add"
        android:showAsAction="ifRoom|withText"
        android:title="@string/txt_add" />

    <item
        android:icon="@drawable/ic_menu_preferences"
        android:id="@+id/men_preferences"
        android:showAsAction="ifRoom|withText"
        android:title="@string/txt_preferences" />
</menu>

<menu
    xmlns:android="http://schemas.android.com/apk/res/android">

    <item
        android:id="@+id/men_details"
        android:title="@string/txt_details" />

    <item
        android:id="@+id/men_edit"
        android:title="@string/txt_edit" />

    <item
        android:id="@+id/men_delete"
        android:title="@string/txt_delete" />
</menu>

这是DetailsActivity:

This is DetailsActivity:

public class ActivityDetails extends FragmentActivity implements FragmentDetails.MyDeleteListener, 
                                                                    FragmentDetails.MyOptionsItemSelectedListener {

    private long id;

    @Override
    public void myDelete(final long id) {
        setResult(RESULT_OK);
        finish();
    }

    @Override
    public void myOptionsItemSelected(final int action, final long id) {
        if (action == R.id.men_add) {
            processEdit(0);
        } else if (action == R.id.men_edit) {
            processEdit(id);
        } else if (action == R.id.men_preferences) {
            processPreferences();
        }
    }

    @Override
    protected void onActivityResult(final int requestCode, final int resultCode, final Intent intent) {
        if (requestCode == MyConstants.DLG_PREFERENCES || requestCode == MyConstants.DLG_TABLE1EDIT) {
            finish();

            startActivity(getIntent()); 
        }
    }

    @Override
    protected void onCreate(final Bundle bundle) {
        super.onCreate(bundle);

        if (bundle != null) {
            if (bundle.containsKey("ID")) {
                id = bundle.getLong("ID");
            }
        } else {
            Bundle bundleExtras = getIntent().getExtras();
            if (bundleExtras != null) {
                id = bundleExtras.getLong("ID");
            }

            processDetails(id);
        }
    }

    @Override
    public void onSaveInstanceState(final Bundle bundle) {
        super.onSaveInstanceState(bundle);

        bundle.putLong("ID", id);
    }

    private void processDetails(final long id) {
        FragmentDetails fragment = new FragmentDetails(id);

        FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
        transaction.replace(android.R.id.content, fragment);
        transaction.commit();
    }

    private void processEdit(final long id) {
        Intent intent = new Intent(this, ActivityEdit.class);
        intent.putExtra("ID", id);
        startActivityForResult(intent, MyConstants.DLG_TABLE1EDIT);
    }

    private void processPreferences() {
        Intent intent = new Intent(this, MyPreferenceActivity.class);
        startActivityForResult(intent, MyConstants.DLG_PREFERENCES);
    }
}

这是带有布局和菜单的DetailsFragment:

Here's the DetailsFragment with Layout and Menu:

public class FragmentDetails extends Fragment {

    private AlertDialog                   alertDialog;
    private MyDeleteListener              deleteListener;
    private long                          id;
    private MyOptionsItemSelectedListener optionsItemSelectedListener;
    private TextView                      textViewDescription;
    private TextView                      textViewId;

    public FragmentDetails() {
        id = 0;
    }

    public FragmentDetails(final long id) {
        this.id = id;
    }

    public long getCurrentId() {
        return id;
    }

    public interface MyDeleteListener {
        public void myDelete(long id);
    }

    public interface MyOptionsItemSelectedListener {
        public void myOptionsItemSelected(int action, long id);
    }

    @Override
    public void onActivityCreated(final Bundle bundle) {
        super.onActivityCreated(bundle);

        if (bundle != null && bundle.containsKey("ID")) {
            id = bundle.getLong("ID");
        }

        setHasOptionsMenu(true);
    }

    @Override
    public void onAttach(final Activity activity) {
        super.onAttach(activity);

        // Reduced
    }

    @Override
    public void onCreateOptionsMenu(final Menu menu, final MenuInflater menuInflater) {
        super.onCreateOptionsMenu(menu, menuInflater);

        menu.clear();

        menuInflater.inflate(R.menu.fragmentdetails, menu);
    }

    @Override
    public View onCreateView(final LayoutInflater inflater, final ViewGroup viewGroup, final Bundle bundle) {
        View view = inflater.inflate(R.layout.fragmentdetails, null);

        textViewDescription = (TextView) view.findViewById(R.id.tv_description);
        textViewId = (TextView) view.findViewById(R.id.tv_id);

        if (id != 0) {
            Table1 table1;
            if ((table1 = MyApplication.getSqliteOpenHelper().getTable1(id)) != null) {
                textViewDescription.setText(Tools.defaultString(table1.getDescription()));
                textViewId.setText(Tools.defaultString(String.valueOf(table1.getId())));
            }
        }

        return view;
    }

    @Override
    public boolean onOptionsItemSelected(final MenuItem menuItem) {
        if (menuItem.getItemId() == R.id.men_delete) {
            processAlertDialog(id);
            return true;
        } else {
            optionsItemSelectedListener.myOptionsItemSelected(menuItem.getItemId(), id);
        }

        return super.onOptionsItemSelected(menuItem);
    }

    @Override
    public void onSaveInstanceState(final Bundle bundle) {
        super.onSaveInstanceState(bundle);

        bundle.putLong("ID", id);
    }

    private void processAlertDialog(final long id) {
        final AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(getActivity());
        alertDialogBuilder.setNegativeButton(android.R.string.cancel, new DialogInterface.OnClickListener() {

            @Override
            public void onClick(final DialogInterface dialogInterface, final int which) {
                alertDialog.dismiss();
                alertDialog = null;
            }
        } );
        alertDialogBuilder.setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {

            @Override
            public void onClick(final DialogInterface dialogInterface, final int which) {
                MyApplication.getSqliteOpenHelper().deleteTable1(id);

                alertDialog.dismiss();
                alertDialog = null;

                deleteListener.myDelete(id);
            }
        } );
        alertDialogBuilder.setCancelable(false);
        alertDialogBuilder.setMessage(R.string.txt_reallydelete);

        alertDialog = alertDialogBuilder.create();
        alertDialog.show();
    }
}

<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_height="wrap_content"
    android:layout_width="match_parent"
    android:orientation="vertical" >

    <LinearLayout
        android:layout_height="wrap_content"
        android:layout_width="match_parent"
        android:orientation="horizontal" >

        <TextView
            style="@style/TextViewStandard"
            android:layout_weight="1" 
            android:text="@string/txt_id" />

        <TextView
            style="@style/TextViewStandard"
            android:id="@+id/tv_id"
            android:layout_weight="1" />
    </LinearLayout>

    <LinearLayout
        android:layout_height="wrap_content"
        android:layout_width="match_parent"
        android:orientation="horizontal" >

        <TextView
            style="@style/TextViewStandard"
            android:layout_weight="1" 
            android:text="@string/txt_description" />

        <TextView
            style="@style/TextViewStandard"
            android:id="@+id/tv_description"
            android:layout_weight="1" />
    </LinearLayout>
</LinearLayout>

<menu
    xmlns:android="http://schemas.android.com/apk/res/android">

    <item
        android:icon="@drawable/ic_menu_add"
        android:id="@+id/men_add"
        android:showAsAction="ifRoom|withText"
        android:title="@string/txt_add" />

    <item
        android:icon="@drawable/ic_menu_edit"
        android:id="@+id/men_edit"
        android:showAsAction="ifRoom|withText"
        android:title="@string/txt_edit" />

    <item
        android:icon="@drawable/ic_menu_delete"
        android:id="@+id/men_delete"
        android:showAsAction="ifRoom|withText"
        android:title="@string/txt_delete" />

    <item
        android:icon="@drawable/ic_menu_preferences"
        android:id="@+id/men_preferences"
        android:showAsAction="ifRoom|withText"
        android:title="@string/txt_preferences" />
</menu>

我不发布EditActivity，因为它只是一个没有片段的FragmentActivity.

I don't post the EditActivity because it's simply an FragmentActivity without a Fragment.

推荐答案

这可能不是全部答案，而是答案的一部分: 您仍然有一个主要活动，在您曾经拥有listview的xml中，现在添加了framelayout.然后在oncreate活动中添加以下内容:

This might not be the whole answer but part of the answer: You still have a main activity, in your xml where you used to have listview you now add a framelayout. Then in your activities oncreate you add following:

        mMainFragment = new ListFragment();
        FragmentManager fragmentManager = getSupportFragmentManager();
        FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();

        fragmentTransaction.replace(R.id.center_container, mMainFragment);

        fragmentTransaction.commit();
        mCurrentFragment = mMainFragment;

在您的片段中

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
    // setup view
    View view = inflater.inflate(R.layout.calendar_list, null);

    mListAdapter = new CustomAdapter(getActivity(), R.layout.calendar_row, (ArrayList<Item>) mFullList);
    setListAdapter(mListAdapter);

    return view;
}

列表片段的XML

<somelayout>
    <ListView android:id="@id/android:list"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>
</somelayout>

点击列表中的片段会触发以下内容:

Click on list is triggered in fragment with:

@Override
public void onListItemClick(ListView list, View view, int position, long id) {
    final Item item = (Item) list.getAdapter().getItem(position);
    mListener.OnListClick(item);
}

哪个使用此侦听器:

公共接口OnListItemClickListener { public void OnListClick(Item item); }

public interface OnListItemClickListener { public void OnListClick(Item item); }

Listfragment需要放在顶部:

The Listfragment needs to have this in top:

@Override
public void onAttach(Activity activity) {
    super.onAttach(activity);
    try {
        mListener = (OnListItemClickListener) activity;
    } catch (ClassCastException e) {
        throw new ClassCastException(activity.toString() + " must implement OnListItemClickListener");
    }
}

然后，主要活动通过实现接口来订阅该活动，并在触发侦听器时启动细节片段.

The main activity then subscribes to this by implementing the interface and start the detail fragment when the listener is triggered.

好的，所以您的问题更为根本:)请记住，每次旋转时在活动中都会调用oncreate，因此您的活动需要记住要显示的片段，就像需要记住要显示的视图一样. 另外，您需要将片段添加到Back Stack中，否则Back键将无法使用它们.将片段视为具有功能的视图，它们不是活动.

Okay, so your question is far more fundamental :) remember oncreate is called in your activity every time you rotate so your activity needs to remember which fragment to show just like it needs to remember which view to show. Also you need to add fragments to the back stack or the back key wont work with them. Think of fragments as views with function, they are not activities.

这篇关于陷入从活动到片段的移植的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！