我编写了一个片段，用于加载来自自定义内容提供商的数据。我已经使用了google示例中的contacts sample program中的游标加载器实现。我目前面临的问题是数据没有显示，并且从下面卡在加载屏幕上。
这是我的片段
public class DealsFragment extends ListFragment implements LoaderManager.LoaderCallbacks<Cursor> {
private static final String ARG_PARAM1 = "param1";
private static final String ARG_PARAM2 = "param2";
private static final String TAG = "DealsFragment";
private static final boolean DEBUG = true;
private DealsAdapter mAdapter;
private static final int LOADER_ID = 1;
// TODO: Rename and change types of parameters
private String mParam1;
private String mParam2;
private DealInteractionListener mListener;
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
setHasOptionsMenu(true);
Uri uri = DealProvider.CONTENT_URI;
Cursor c = getActivity().getContentResolver().query(uri,null,null,null,null);
//mAdapter = new DealCursorAdapter(getActivity(),c);
//mAdapter = new DealListAdapter(getActivity());
String[] columns = {DealProvider.ID,DealProvider.DEAL_DATA};
int[] ids = {R.id.promotion_name,R.id.promotion_description};
mAdapter = new DealsAdapter(getActivity());
setEmptyText("No applications");
setListAdapter(mAdapter);
setListShown(false);
if (DEBUG) {
Log.i(TAG, "+++ Calling initLoader()! +++");
if (getLoaderManager().getLoader(LOADER_ID) == null) {
Log.i(TAG, "+++ Initializing the new Loader... +++");
} else {
Log.i(TAG, "+++ Reconnecting with existing Loader (id '1')... +++");
}
}
getLoaderManager().initLoader(LOADER_ID, null, this);
}
public static DealsFragment newInstance(String param1, String param2) {
DealsFragment fragment = new DealsFragment();
Bundle args = new Bundle();
args.putString(ARG_PARAM1, param1);
args.putString(ARG_PARAM2, param2);
fragment.setArguments(args);
return fragment;
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
return super.onCreateView(inflater, container, savedInstanceState);
}
/**
* Mandatory empty constructor for the fragment manager to instantiate the
* fragment (e.g. upon screen orientation changes).
*/
public DealsFragment() {
}
void insertDeal(String data){
ContentValues values = new ContentValues();
values.put(DealProvider.DEAL_DATA, data);
Uri uri = getActivity().getContentResolver().insert(
DealProvider.CONTENT_URI, values);
Log.d(TAG,"DealInserted");
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getArguments() != null) {
mParam1 = getArguments().getString(ARG_PARAM1);
mParam2 = getArguments().getString(ARG_PARAM2);
}
}
@Override
public void onAttach(Activity activity) {
super.onAttach(activity);
insertDeal("Hello World");
try {
mListener = (DealInteractionListener) activity;
} catch (ClassCastException e) {
throw new ClassCastException(activity.toString()
+ " must implement OnFragmentInteractionListener");
}
}
@Override
public void onDetach() {
super.onDetach();
mListener = null;
}
@Override
public void onListItemClick(ListView l, View v, int position, long id) {
super.onListItemClick(l, v, position, id);
final Cursor cursor = mAdapter.getCursor();
cursor.moveToPosition(position);
if (null != mListener) {
// Notify the active callbacks interface (the activity, if the
// fragment is attached to one) that an item has been selected.
mListener.onDealSelected(DummyContent.ITEMS.get(position).id);
}
}
/**********************/
/** LOADER CALLBACKS **/
/**********************/
@Override
public Loader<Cursor> onCreateLoader(int id, Bundle args) {
Uri uri = DealProvider.CONTENT_URI;
return new CursorLoader(getActivity(), uri, null, null, null, null);
}
@Override
public void onLoadFinished(Loader<Cursor> loader, Cursor data) {
Log.d(TAG,"Swapping with new cursor");
mAdapter.swapCursor(data);
}
@Override
public void onLoaderReset(Loader<Cursor> loader) {
mAdapter.swapCursor(null);
}
/**
* This interface must be implemented by activities that contain this
* fragment to allow an interaction in this fragment to be communicated
* to the activity and potentially other fragments contained in that
* activity.
* <p/>
* See the Android Training lesson <a href=
* "http://developer.android.com/training/basics/fragments/communicating.html"
* >Communicating with Other Fragments</a> for more information.
*/
public interface DealInteractionListener {
// TODO: Update argument type and name
public void onDealSelected(String id);
}
private class DealsAdapter extends CursorAdapter{
private LayoutInflater mInflater;
public DealsAdapter(Context context) {
super(context, null,0);
mInflater = LayoutInflater.from(context);
}
private class ViewHolder {
TextView text1;
TextView text2;
ImageView img;
}
@Override
public View newView(Context context, Cursor cursor, ViewGroup parent) {
final View itemLayout =
mInflater.inflate(R.layout.deal_list_item, parent, false);
final ViewHolder holder = new ViewHolder();
holder.text1 = (TextView) itemLayout.findViewById(R.id.promotion_name);
holder.text2 = (TextView) itemLayout.findViewById(R.id.promotion_description);
holder.img = (ImageView) itemLayout.findViewById(R.id.imageView3);
itemLayout.setTag(holder);
return itemLayout;
}
@Override
public void bindView(View view, Context context, Cursor cursor) {
final ViewHolder holder = (ViewHolder) view.getTag();
final String data = cursor.getString(1);
final int id = cursor.getInt(0);
try {
JSONObject deal = new JSONObject(data);
String deal_name = deal.getString("deal_name");
String deal_desc = deal.getString("deal_description");
holder.text1.setText(deal_name);
holder.text2.setText(deal_desc);
String deal_url = deal.getString("deal_url");
DownloadImageTask d = new DownloadImageTask(holder.img);
d.execute(deal_url);
} catch (JSONException e) {
e.printStackTrace();
}
}
@Override
public Cursor swapCursor(Cursor newCursor) {
return super.swapCursor(newCursor);
}
@Override
public int getCount() {
return super.getCount();
}
}
和内容提供商
public class DealProvider extends ContentProvider {
static final String PROVIDER_NAME = "com.idisplay.frags.dealProvider";
static final String URL = "content://" +PROVIDER_NAME + "/deals";
public static final Uri CONTENT_URI = Uri.parse(URL);
// Creates a UriMatcher object.
//private static final UriMatcher sUriMatcher;
public static final String ID = "_id";
public static final String DEAL_DATA = "deal_data";
static final int DEALS = 1;
static final int DEALS_ID = 2;
DBHelper dbHelper;
private static HashMap<String, String> DealMap;
static final UriMatcher uriMatcher;
static{
uriMatcher = new UriMatcher(UriMatcher.NO_MATCH);
uriMatcher.addURI(PROVIDER_NAME, "deals", DEALS);
uriMatcher.addURI(PROVIDER_NAME, "deals/#", DEALS_ID);
}
private SQLiteDatabase database;
static final String DATABASE_NAME = "myapp";
static final String TABLE_NAME = "deals";
static final int DATABASE_VERSION = 1;
static final String CREATE_TABLE =
" CREATE TABLE " + TABLE_NAME +
" (_id INTEGER PRIMARY KEY AUTOINCREMENT, " +
" deal_data TEXT NOT NULL);";
public DealProvider() {
// sUriMatcher = new UriMatcher(0);
}
@Override
public int delete(Uri uri, String selection, String[] selectionArgs) {
// Implement this to handle requests to delete one or more rows.
int count = 0;
switch (uriMatcher.match(uri)){
case DEALS:
// delete all the records of the table
count = database.delete(TABLE_NAME, selection, selectionArgs);
break;
case DEALS_ID:
String id = uri.getLastPathSegment(); //gets the id
count = database.delete( TABLE_NAME, ID + " = " + id +
(!TextUtils.isEmpty(selection) ? " AND (" +
selection + ')' : ""), selectionArgs);
break;
default:
throw new IllegalArgumentException("Unsupported URI " + uri);
}
getContext().getContentResolver().notifyChange(uri, null);
return count;
}
@Override
public String getType(Uri uri) {
// switch (uriMatcher.match(uri)){
// // Get all friend-birthday records
// case DEALS:
// return "vnd.android.cursor.dir/vnd.example.friends";
// // Get a particular friend
// case DEALS_ID:
// return "vnd.android.cursor.item/vnd.example.friends";
// default:
// throw new IllegalArgumentException("Unsupported URI: " + uri);
// }
return "";
}
@Override
public Uri insert(Uri uri, ContentValues values) {
long row = database.insert(TABLE_NAME, "", values);
// If record is added successfully
if(row > 0) {
Uri newUri = ContentUris.withAppendedId(CONTENT_URI, row);
getContext().getContentResolver().notifyChange(newUri, null);
return newUri;
}
throw new SQLException("Fail to add a new record into " + uri);
}
@Override
public boolean onCreate() {
Context context = getContext();
dbHelper = new DBHelper(context);
// permissions to be writable
database = dbHelper.getWritableDatabase();
if(database == null)
return false;
else
return true;
}
@Override
public Cursor query(Uri uri, String[] projection, String selection,
String[] selectionArgs, String sortOrder) {
SQLiteQueryBuilder queryBuilder = new SQLiteQueryBuilder();
// the TABLE_NAME to query on
queryBuilder.setTables(TABLE_NAME);
switch (uriMatcher.match(uri)) {
// maps all database column names
case DEALS:
queryBuilder.setProjectionMap(DealMap);
break;
case DEALS_ID:
queryBuilder.appendWhere( ID + "=" + uri.getLastPathSegment());
break;
default:
throw new IllegalArgumentException("Unknown URI " + uri);
}
Cursor cursor = queryBuilder.query(database, projection, selection,
selectionArgs, null, null, sortOrder);
/**
* register to watch a content URI for changes
*/
cursor.setNotificationUri(getContext().getContentResolver(), uri);
return cursor;
}
@Override
public int update(Uri uri, ContentValues values, String selection,
String[] selectionArgs) {
int count = 0;
switch (uriMatcher.match(uri)){
case DEALS:
count = database.update(TABLE_NAME, values, selection, selectionArgs);
break;
case DEALS_ID:
count = database.update(TABLE_NAME, values, ID +
" = " + uri.getLastPathSegment() +
(!TextUtils.isEmpty(selection) ? " AND (" +
selection + ')' : ""), selectionArgs);
break;
default:
throw new IllegalArgumentException("Unsupported URI " + uri );
}
getContext().getContentResolver().notifyChange(uri, null);
return count;
}
private class DBHelper extends SQLiteOpenHelper {
public DBHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL(CREATE_TABLE);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
Log.w(DBHelper.class.getName(),
"Upgrading database from version " + oldVersion + " to "
+ newVersion + ". Old data will be destroyed");
db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME);
onCreate(db);
}
}
}
答案 0 :(得分：0)
函数setListShown（false）未显示正在加载的列表。