Android - CursorAdapter 不工作
Android - CursorAdapter doesn't work
我有一个 ChatActivity,它通过 CursorLoader 加载它的数据。 CursorLoader return 一个有两个寄存器的游标,但是永远不会调用适配器中的 newView 和 bindView 方法。
我的activity
public class ChatActivity extends BaseActivity implements LoaderManager.LoaderCallbacks<Cursor> {
public static final String EXTRA_AMANTEID = "amanteId";
private EditText messageET;
private ListView messagesContainer;
private Button sendBtn;
private ChatAdapter adapter;
private Long amanteId;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_chat);
amanteId = getIntent().getLongExtra(ChatActivity.EXTRA_AMANTEID, 0L);
messagesContainer = (ListView) findViewById(R.id.messagesContainer);
messageET = (EditText) findViewById(R.id.messageEdit);
sendBtn = (Button) findViewById(R.id.chatSendButton);
RelativeLayout container = (RelativeLayout) findViewById(R.id.container);
adapter = new ChatAdapter(this);
getLoaderManager().initLoader(0, null, this);
messagesContainer.setAdapter(adapter);
}
private void scroll() {
messagesContainer.setSelection(messagesContainer.getCount() - 1);
}
@Override
public Loader<Cursor> onCreateLoader(int i, Bundle bundle) {
return new CursorLoader(ChatActivity.this, MensagemProvider.CONTENT_URI_CONVERSA, null, null, new String[]{Long.toString(amanteId), Long.toString(amanteId)}, null);
}
@Override
public void onLoadFinished(Loader<Cursor> loader, Cursor cursor) {
adapter.swapCursor(cursor);
}
@Override
public void onLoaderReset(Loader<Cursor> loader) {
adapter.swapCursor(null);
}
}
我的适配器
public class ChatAdapter extends CursorAdapter {
private Cursor cursor;
private int dataEnvioColumnIndex;
private int idMensagemColumnIndex;
private int idRemetenteColumnIndex;
private int idDestinatarioColumnIndex;
private int apelidoRemetenteColumnIndex;
private int apelidoDestinatarioColumnIndex;
private int textoMensagemColumnIndex;
private long idColaboradorLogado;
public ChatAdapter(Context context) {
super(context, null, false);
}
public ChatMessage getItem() {
ChatMessage message = new ChatMessage();
SimpleDateFormat dt = new SimpleDateFormat("dd/MM/yyyy HH:mm:ss");
Date dataEnvio = new Date(cursor.getLong(dataEnvioColumnIndex));
message.setDate(dt.format(dataEnvio));
message.setId(cursor.getLong(idMensagemColumnIndex));
Long de = cursor.getLong(idRemetenteColumnIndex);
Long logado = BaseApp.getCredentials().getId();
message.setMe(de.equals(logado));
message.setMessage(cursor.getString(textoMensagemColumnIndex));
return message;
}
@Override
public View newView(Context context, Cursor cursor, ViewGroup parent) {
LayoutInflater vi = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View retView = vi.inflate(R.layout.list_item_chat_message, null);
return retView;
}
@Override
public void bindView(View view, Context context, Cursor cursor) {
ViewHolder holder = createViewHolder(view);;
view.setTag(holder);
ChatMessage chatMessage = getItem();
boolean myMsg = chatMessage.getIsme() ;//Just a dummy check
holder.txtMessage.setText(chatMessage.getMessage());
holder.txtInfo.setText(chatMessage.getDate());
}
private ViewHolder createViewHolder(View v) {
ViewHolder holder = new ViewHolder();
holder.txtMessage = (TextView) v.findViewById(R.id.txtMessage);
holder.content = (LinearLayout) v.findViewById(R.id.content);
holder.contentWithBG = (LinearLayout) v.findViewById(R.id.contentWithBackground);
holder.txtInfo = (TextView) v.findViewById(R.id.txtInfo);
return holder;
}
private static class ViewHolder {
public TextView txtMessage;
public TextView txtInfo;
public LinearLayout content;
public LinearLayout contentWithBG;
}
@Override
public Cursor swapCursor(Cursor cursor) {
if(cursor!=null) {
cursor.moveToFirst();
idMensagemColumnIndex = cursor.getColumnIndex(MensagemProvider.COLUMN_MENSAGEMID);
idRemetenteColumnIndex = cursor.getColumnIndex(MensagemProvider.COLUMN_DE);
idDestinatarioColumnIndex = cursor.getColumnIndex(MensagemProvider.COLUMN_PARA);
apelidoRemetenteColumnIndex = cursor.getColumnIndex(MensagemProvider.COLUMN_APELIDO_REMETENTE);
apelidoDestinatarioColumnIndex = cursor.getColumnIndex(MensagemProvider.COLUMN_APELIDO_DESTINATARIO);
textoMensagemColumnIndex = cursor.getColumnIndex(MensagemProvider.COLUMN_MENSAGEM);
}
notifyDataSetChanged();
return cursor;
}
}
我做错了什么?有谁能够帮助我 ?
谢谢!
覆盖swapCursor()
是自找麻烦。光标不会定位在适配器期望它定位的位置(在 first 之前)。而且您不调用 super.swapCursor()
,因此适配器从未真正听说过新游标。
我敢打赌,您正在尝试 "optimize" 每次交换新游标时只获取一次列索引。
首先尝试摆脱 swapCursor()
覆盖并在 getItem()
方法中进行 getColumnIndex()
调用。如果这样可行并且您仍然真的希望每个游标只调用一次 getColumnIndex()
,您可以尝试在交换游标时将所有游标索引设置为 -1,然后在 [=] 中调用 getColumnIndex()
14=]仅当索引为-1时。
但不要乱用 swapCursor()
,尤其是在不调用 super.swapCursor()
并返回其结果的情况下。
我有一个 ChatActivity,它通过 CursorLoader 加载它的数据。 CursorLoader return 一个有两个寄存器的游标,但是永远不会调用适配器中的 newView 和 bindView 方法。
我的activity
public class ChatActivity extends BaseActivity implements LoaderManager.LoaderCallbacks<Cursor> {
public static final String EXTRA_AMANTEID = "amanteId";
private EditText messageET;
private ListView messagesContainer;
private Button sendBtn;
private ChatAdapter adapter;
private Long amanteId;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_chat);
amanteId = getIntent().getLongExtra(ChatActivity.EXTRA_AMANTEID, 0L);
messagesContainer = (ListView) findViewById(R.id.messagesContainer);
messageET = (EditText) findViewById(R.id.messageEdit);
sendBtn = (Button) findViewById(R.id.chatSendButton);
RelativeLayout container = (RelativeLayout) findViewById(R.id.container);
adapter = new ChatAdapter(this);
getLoaderManager().initLoader(0, null, this);
messagesContainer.setAdapter(adapter);
}
private void scroll() {
messagesContainer.setSelection(messagesContainer.getCount() - 1);
}
@Override
public Loader<Cursor> onCreateLoader(int i, Bundle bundle) {
return new CursorLoader(ChatActivity.this, MensagemProvider.CONTENT_URI_CONVERSA, null, null, new String[]{Long.toString(amanteId), Long.toString(amanteId)}, null);
}
@Override
public void onLoadFinished(Loader<Cursor> loader, Cursor cursor) {
adapter.swapCursor(cursor);
}
@Override
public void onLoaderReset(Loader<Cursor> loader) {
adapter.swapCursor(null);
}
}
我的适配器
public class ChatAdapter extends CursorAdapter {
private Cursor cursor;
private int dataEnvioColumnIndex;
private int idMensagemColumnIndex;
private int idRemetenteColumnIndex;
private int idDestinatarioColumnIndex;
private int apelidoRemetenteColumnIndex;
private int apelidoDestinatarioColumnIndex;
private int textoMensagemColumnIndex;
private long idColaboradorLogado;
public ChatAdapter(Context context) {
super(context, null, false);
}
public ChatMessage getItem() {
ChatMessage message = new ChatMessage();
SimpleDateFormat dt = new SimpleDateFormat("dd/MM/yyyy HH:mm:ss");
Date dataEnvio = new Date(cursor.getLong(dataEnvioColumnIndex));
message.setDate(dt.format(dataEnvio));
message.setId(cursor.getLong(idMensagemColumnIndex));
Long de = cursor.getLong(idRemetenteColumnIndex);
Long logado = BaseApp.getCredentials().getId();
message.setMe(de.equals(logado));
message.setMessage(cursor.getString(textoMensagemColumnIndex));
return message;
}
@Override
public View newView(Context context, Cursor cursor, ViewGroup parent) {
LayoutInflater vi = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View retView = vi.inflate(R.layout.list_item_chat_message, null);
return retView;
}
@Override
public void bindView(View view, Context context, Cursor cursor) {
ViewHolder holder = createViewHolder(view);;
view.setTag(holder);
ChatMessage chatMessage = getItem();
boolean myMsg = chatMessage.getIsme() ;//Just a dummy check
holder.txtMessage.setText(chatMessage.getMessage());
holder.txtInfo.setText(chatMessage.getDate());
}
private ViewHolder createViewHolder(View v) {
ViewHolder holder = new ViewHolder();
holder.txtMessage = (TextView) v.findViewById(R.id.txtMessage);
holder.content = (LinearLayout) v.findViewById(R.id.content);
holder.contentWithBG = (LinearLayout) v.findViewById(R.id.contentWithBackground);
holder.txtInfo = (TextView) v.findViewById(R.id.txtInfo);
return holder;
}
private static class ViewHolder {
public TextView txtMessage;
public TextView txtInfo;
public LinearLayout content;
public LinearLayout contentWithBG;
}
@Override
public Cursor swapCursor(Cursor cursor) {
if(cursor!=null) {
cursor.moveToFirst();
idMensagemColumnIndex = cursor.getColumnIndex(MensagemProvider.COLUMN_MENSAGEMID);
idRemetenteColumnIndex = cursor.getColumnIndex(MensagemProvider.COLUMN_DE);
idDestinatarioColumnIndex = cursor.getColumnIndex(MensagemProvider.COLUMN_PARA);
apelidoRemetenteColumnIndex = cursor.getColumnIndex(MensagemProvider.COLUMN_APELIDO_REMETENTE);
apelidoDestinatarioColumnIndex = cursor.getColumnIndex(MensagemProvider.COLUMN_APELIDO_DESTINATARIO);
textoMensagemColumnIndex = cursor.getColumnIndex(MensagemProvider.COLUMN_MENSAGEM);
}
notifyDataSetChanged();
return cursor;
}
}
我做错了什么?有谁能够帮助我 ? 谢谢!
覆盖swapCursor()
是自找麻烦。光标不会定位在适配器期望它定位的位置(在 first 之前)。而且您不调用 super.swapCursor()
,因此适配器从未真正听说过新游标。
我敢打赌,您正在尝试 "optimize" 每次交换新游标时只获取一次列索引。
首先尝试摆脱 swapCursor()
覆盖并在 getItem()
方法中进行 getColumnIndex()
调用。如果这样可行并且您仍然真的希望每个游标只调用一次 getColumnIndex()
,您可以尝试在交换游标时将所有游标索引设置为 -1,然后在 [=] 中调用 getColumnIndex()
14=]仅当索引为-1时。
但不要乱用 swapCursor()
,尤其是在不调用 super.swapCursor()
并返回其结果的情况下。