SimpleCursorTreeAdapter和CursorLoader的ExpandableListViewSimpleCursorTreeAdapter、CursorLoader、Expandab
我想通过使用异步查询提供一个 CursorLoader 与 SimpleCursorTreeAdapter
I am trying to asynchronously query a provider by using a CursorLoader with a SimpleCursorTreeAdapter
下面是我的片段类，它实现了 CursorLoader
Here is my Fragment class which implements the CursorLoader
public class GroupsListFragment extends ExpandableListFragment implements
LoaderManager.LoaderCallbacks<Cursor> {
private final String DEBUG_TAG = getClass().getSimpleName().toString();
private static final String[] CONTACTS_PROJECTION = new String[] {
ContactsContract.Contacts._ID,
ContactsContract.Contacts.DISPLAY_NAME };
private static final String[] GROUPS_SUMMARY_PROJECTION = new String[] {
ContactsContract.Groups.TITLE, ContactsContract.Groups._ID,
ContactsContract.Groups.SUMMARY_COUNT,
ContactsContract.Groups.ACCOUNT_NAME,
ContactsContract.Groups.ACCOUNT_TYPE,
ContactsContract.Groups.DATA_SET };
GroupsAdapter mAdapter;
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
populateContactList();
getLoaderManager().initLoader(-1, null, this);
}
public Loader<Cursor> onCreateLoader(int id, Bundle args) {
// This is called when a new Loader needs to be created.
Log.d(DEBUG_TAG, "onCreateLoader for loader_id " + id);
CursorLoader cl;
if (id != -1) {
// child cursor
Uri contactsUri = ContactsContract.Data.CONTENT_URI;
String selection = "(("
+ ContactsContract.CommonDataKinds.GroupMembership.DISPLAY_NAME
+ " NOTNULL) AND ("
+ ContactsContract.CommonDataKinds.GroupMembership.HAS_PHONE_NUMBER
+ "=1) AND ("
+ ContactsContract.CommonDataKinds.GroupMembership.DISPLAY_NAME
+ " != '') AND ("
+ ContactsContract.CommonDataKinds.GroupMembership.GROUP_ROW_ID
+ " = ? ))";
String sortOrder = ContactsContract.CommonDataKinds.GroupMembership.DISPLAY_NAME
+ " COLLATE LOCALIZED ASC";
String[] selectionArgs = new String[] { String.valueOf(id) };
cl = new CursorLoader(getActivity(), contactsUri,
CONTACTS_PROJECTION, selection, selectionArgs, sortOrder);
} else {
// group cursor
Uri groupsUri = ContactsContract.Groups.CONTENT_SUMMARY_URI;
String selection = "((" + ContactsContract.Groups.TITLE
+ " NOTNULL) AND (" + ContactsContract.Groups.TITLE
+ " != '' ))";
String sortOrder = ContactsContract.Groups.TITLE
+ " COLLATE LOCALIZED ASC";
cl = new CursorLoader(getActivity(), groupsUri,
GROUPS_SUMMARY_PROJECTION, selection, null, sortOrder);
}
return cl;
}
public void onLoadFinished(Loader<Cursor> loader, Cursor data) {
// Swap the new cursor in.
int id = loader.getId();
Log.d(DEBUG_TAG, "onLoadFinished() for loader_id " + id);
if (id != -1) {
// child cursor
if (!data.isClosed()) {
Log.d(DEBUG_TAG, "data.getCount() " + data.getCount());
try {
mAdapter.setChildrenCursor(id, data);
} catch (NullPointerException e) {
Log.w("DEBUG","Adapter expired, try again on the next query: "
+ e.getMessage());
}
}
} else {
mAdapter.setGroupCursor(data);
}
}
public void onLoaderReset(Loader<Cursor> loader) {
// This is called when the last Cursor provided to onLoadFinished()
// is about to be closed.
int id = loader.getId();
Log.d(DEBUG_TAG, "onLoaderReset() for loader_id " + id);
if (id != -1) {
// child cursor
try {
mAdapter.setChildrenCursor(id, null);
} catch (NullPointerException e) {
Log.w("TAG", "Adapter expired, try again on the next query: "
+ e.getMessage());
}
} else {
mAdapter.setGroupCursor(null);
}
}
/**
* Populate the contact list
*/
private void populateContactList() {
// Set up our adapter
mAdapter = new GroupsAdapter(getActivity(),this,
android.R.layout.simple_expandable_list_item_1,
android.R.layout.simple_expandable_list_item_1,
new String[] { ContactsContract.Groups.TITLE }, // Name for group layouts
new int[] { android.R.id.text1 },
new String[] { ContactsContract.Contacts.DISPLAY_NAME }, // Name for child layouts
new int[] { android.R.id.text1 });
setListAdapter(mAdapter);
}
}
和这里是我的适配器，它的子类 SimpleCursorTreeAdapter
And here is my adapter which subclasses SimpleCursorTreeAdapter
public class GroupsAdapter extends SimpleCursorTreeAdapter {
private final String DEBUG_TAG = getClass().getSimpleName().toString();
private ContactManager mActivity;
private GroupsListFragment mFragment;
// Note that the constructor does not take a Cursor. This is done to avoid
// querying the database on the main thread.
public GroupsAdapter(Context context, GroupsListFragment glf,
int groupLayout, int childLayout, String[] groupFrom,
int[] groupTo, String[] childrenFrom, int[] childrenTo) {
super(context, null, groupLayout, groupFrom, groupTo, childLayout,
childrenFrom, childrenTo);
mActivity = (ContactManager) context;
mFragment = glf;
}
@Override
protected Cursor getChildrenCursor(Cursor groupCursor) {
// Given the group, we return a cursor for all the children within that group
int groupId = groupCursor.getInt(groupCursor
.getColumnIndex(ContactsContract.Groups._ID));
Log.d(DEBUG_TAG, "getChildrenCursor() for groupId " + groupId);
Loader loader = mActivity.getLoaderManager().getLoader(groupId);
if ( loader != null && loader.isReset() ) {
mActivity.getLoaderManager().restartLoader(groupId, null, mFragment);
} else {
mActivity.getLoaderManager().initLoader(groupId, null, mFragment);
}
}
}
现在的问题是，当我点击父组三种情况之一发生在这似乎是一个矛盾的方式之一。
The problem is that when i click one of the parent groups one of three things happens in what appears to be a inconsistent fashion.
1）无论是基打开和它下面的儿童出现
1) Either the group opens up and the children appear below it
2）本集团不开和 setChildrenCursor（）调用抛出 NullPointerException异常错误，被抓住的在try catch块
2) The group does not open and the setChildrenCursor() call throws an NullPointerException error which gets caught in the try catch block
3）本集团不开放，不会引发错误
3) The group does not open and no error is thrown
下面是一些调试输出的场景，其中一组被扩大，显示出孩子们：
Here is some debugging output in a scenario in which a group is expanded and showing the children:
在将显示所有组它。OUPUTS：
When all groups are displayed it ouputs:
05-20 10:08:22.765: D/GroupsListFragment(22132): onCreateLoader for loader_id -1
05-20 10:08:23.613: D/GroupsListFragment(22132): onLoadFinished() for loader_id -1
-1是组光标loader_id
-1 is the loader_id of the group cursor
那么，如果我选择一组特别是（我们叫它A组），它输出：
Then if i select one group in particular (let's just call it group A) it outputs:
05-20 23:22:31.140: D/GroupsAdapter(13844): getChildrenCursor() for groupId 67
05-20 23:22:31.140: D/GroupsListFragment(13844): onCreateLoader for loader_id 67
05-20 23:22:31.254: D/GroupsListFragment(13844): onLoadFinished() for loader_id 67
05-20 23:22:31.254: D/GroupsListFragment(13844): data.getCount() 4
05-20 23:22:31.254: W/GroupsListFragment(13844): Adapter expired, try again on the next query: null
本集团并无扩大和 NullPointerException异常被捕获。然后，如果我选择另一个组（我们叫它B组），它输出：
The group does not expand and the NullPointerException is caught. Then if i select another group (let's just call it group B) it outputs:
05-20 23:25:38.089: D/GroupsAdapter(13844): getChildrenCursor() for groupId 3
05-20 23:25:38.089: D/GroupsListFragment(13844): onCreateLoader for loader_id 3
05-20 23:25:38.207: D/GroupsListFragment(13844): onLoadFinished() for loader_id 3
05-20 23:25:38.207: D/GroupsListFragment(13844): data.getCount() 6
这一次， NullPointerException异常不抛出。而不是B组扩大和A组展开。
This time, the NullPointerException is not thrown. And instead of group B expanding, group A is expanded.
谁能解释说， setChildrenCursor（）呼叫展出的行为？
Can anyone explain the behavior that the setChildrenCursor() call is exhibiting?
我想有一个与该组/子CursorLoaders被实例化 onCreateLoader一个问题（）。对于组 CursorLoader 我只是想在我的手机中的所有群体。孩子 CursorLoader 应包含组中的所有联系人。有没有人有任何想法可能是什么问题？
I am thinking there is a problem with how the group/child CursorLoaders are instantiated in onCreateLoader(). For the group CursorLoader i just want all groups in my phone. The child CursorLoader should contain all contacts within a group. Does anyone have any ideas what could be the issue?
更新
感谢@荫的意见，我现在已经修改了 getChildrenCursor（）方法。我现在选择的groupCursor位置不ContactsContract.Groups._ID的值传递到initLoader（）调用。我也改变了逻辑调用restartLoader（）只有当加载程序是不是null，装载机isReset是假的。
Thanks to @Yam's advice I have now modified the getChildrenCursor() method. I am now selecting the groupCursor position not the value of ContactsContract.Groups._ID to pass into the initLoader() call. I also changed the logic to call restartLoader() only when loader is not null and loader isReset is false.
protected Cursor getChildrenCursor(Cursor groupCursor) {
// Given the group, we return a cursor for all the children within that
// group
int groupPos = groupCursor.getPosition();
Log.d(DEBUG_TAG, "getChildrenCursor() for groupPos " + groupPos);
Loader loader = mActivity.getLoaderManager().getLoader(groupPos);
if (loader != null && !loader.isReset()) {
mActivity.getLoaderManager().restartLoader(groupPos, null, mFragment);
} else {
mActivity.getLoaderManager().initLoader(groupPos, null, mFragment);
}
return null;
}
这无疑更有意义，并且不出现一些一群有时并不能扩大其他时间飘忽不定的行为。
This definitely makes more sense and does not exhibit some of the erratic behavior of a group expanding sometimes and not other times.
但是，也有正在下它们不属于一组显示的联系人。还有些团体确实有他们的接触，但不会表现出任何的接触。如此看来，在 getChildrenCursor（）问题现在可以解决了。
However, there are contacts that are being displayed under a group that they don't belong to. And also some groups that do have contacts in them but it won't show any contacts. So it seems that the getChildrenCursor() issues may now be resolved.
但现在看起来是多么的CursorLoaders实例化的 onCreateLoader（）方法的问题。在 CursorLoader 在 onCreateLoader（）的方法为孩子光标返回被实例化不当？
But now it looks to be an issue of how the CursorLoaders are instantiated in the onCreateLoader() method. Is the CursorLoader returned in the onCreateLoader() method for the child cursor being instantiated improperly?
更新
所以我确定了我的问题之一。在 getChildrenCursor（）方法，如果我传递的groupId到 initLoader（）方法，然后在 onCreateLoader（）方法，当 CursorLoader 创建它会得到查询的正确的组ID参数。然而，在 onLoadFinished（）调用 setChildrenCursor（）被获得通过装载器的ID为第一个参数不该groupPosition。我猜我要地图加载器的ID分组位置在一些数据结构。但我不知道这是最好的办法。有没有人有什么建议？
So I have identified one of my issues. In the getChildrenCursor() method if I pass the groupId into the initLoader() method then in the onCreateLoader() method, when the CursorLoader is created it will get the correct groupid parameter for the query. However, in the onLoadFinished() the call to setChildrenCursor() is getting passed the loader id for the first parameter not the groupPosition. I'm guessing i have to map loader ids to group positions in some data structure. But i'm not sure if this is the best approach. Does anyone have any suggestions?
推荐答案
所以我想通了，我需要映射loaderids到groupPositions，这解决了我的问题：
So i figured out that I needed to map loaderids to groupPositions and this solved my issue:
下面是我的片段类，它实现了 CursorLoader
Here is my Fragment class which implements the CursorLoader
public class GroupsListFragment extends ExpandableListFragment implements
LoaderManager.LoaderCallbacks<Cursor> {
private final String DEBUG_TAG = getClass().getSimpleName().toString();
private static final String[] CONTACTS_PROJECTION = new String[] {
ContactsContract.Contacts._ID,
ContactsContract.Contacts.DISPLAY_NAME };
private static final String[] GROUPS_PROJECTION = new String[] {
ContactsContract.Groups.TITLE, ContactsContract.Groups._ID };
GroupsAdapter mAdapter;
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
populateContactList();
// Prepare the loader. Either re-connect with an existing one,
// or start a new one.
Loader loader = getLoaderManager().getLoader(-1);
if (loader != null && !loader.isReset()) {
getLoaderManager().restartLoader(-1, null, this);
} else {
getLoaderManager().initLoader(-1, null, this);
}
}
public Loader<Cursor> onCreateLoader(int id, Bundle args) {
// This is called when a new Loader needs to be created.
Log.d(DEBUG_TAG, "onCreateLoader for loader_id " + id);
CursorLoader cl;
if (id != -1) {
// child cursor
Uri contactsUri = ContactsContract.Data.CONTENT_URI;
String selection = "((" + ContactsContract.Contacts.DISPLAY_NAME
+ " NOTNULL) AND ("
+ ContactsContract.Contacts.HAS_PHONE_NUMBER + "=1) AND ("
+ ContactsContract.Contacts.DISPLAY_NAME + " != '') AND ("
+ ContactsContract.CommonDataKinds.GroupMembership.GROUP_ROW_ID
+ " = ? ))";
String sortOrder = ContactsContract.Contacts.DISPLAY_NAME
+ " COLLATE LOCALIZED ASC";
String[] selectionArgs = new String[] { String.valueOf(id) };
cl = new CursorLoader(getActivity(), contactsUri,
CONTACTS_PROJECTION, selection, selectionArgs, sortOrder);
} else {
// group cursor
Uri groupsUri = ContactsContract.Groups.CONTENT_URI;
String selection = "((" + ContactsContract.Groups.TITLE
+ " NOTNULL) AND (" + ContactsContract.Groups.TITLE
+ " != '' ))";
String sortOrder = ContactsContract.Groups.TITLE
+ " COLLATE LOCALIZED ASC";
cl = new CursorLoader(getActivity(), groupsUri,
GROUPS_PROJECTION, selection, null, sortOrder);
}
return cl;
}
public void onLoadFinished(Loader<Cursor> loader, Cursor data) {
// Swap the new cursor in.
int id = loader.getId();
Log.d(DEBUG_TAG, "onLoadFinished() for loader_id " + id);
if (id != -1) {
// child cursor
if (!data.isClosed()) {
Log.d(DEBUG_TAG, "data.getCount() " + data.getCount());
HashMap<Integer,Integer> groupMap = mAdapter.getGroupMap();
try {
int groupPos = groupMap.get(id);
Log.d(DEBUG_TAG, "onLoadFinished() for groupPos " + groupPos);
mAdapter.setChildrenCursor(groupPos, data);
} catch (NullPointerException e) {
Log.w("DEBUG","Adapter expired, try again on the next query: "
+ e.getMessage());
}
}
} else {
mAdapter.setGroupCursor(data);
}
}
public void onLoaderReset(Loader<Cursor> loader) {
// This is called when the last Cursor provided to onLoadFinished()
// is about to be closed.
int id = loader.getId();
Log.d(DEBUG_TAG, "onLoaderReset() for loader_id " + id);
if (id != -1) {
// child cursor
try {
mAdapter.setChildrenCursor(id, null);
} catch (NullPointerException e) {
Log.w("TAG", "Adapter expired, try again on the next query: "
+ e.getMessage());
}
} else {
mAdapter.setGroupCursor(null);
}
}
/**
* Populate the contact list
*/
private void populateContactList() {
// Set up our adapter
mAdapter = new GroupsAdapter(getActivity(),this,
android.R.layout.simple_expandable_list_item_1,
android.R.layout.simple_expandable_list_item_1,
new String[] { ContactsContract.Groups.TITLE }, // Name for group layouts
new int[] { android.R.id.text1 },
new String[] { ContactsContract.Contacts.DISPLAY_NAME }, // Name for child layouts
new int[] { android.R.id.text1 });
setListAdapter(mAdapter);
}
}
和这里是我的适配器，它的子类 SimpleCursorTreeAdapter
And here is my adapter which subclasses SimpleCursorTreeAdapter
public class GroupsAdapter extends SimpleCursorTreeAdapter {
private final String DEBUG_TAG = getClass().getSimpleName().toString();
private ContactManager mActivity;
private GroupsListFragment mFragment;
protected final HashMap<Integer, Integer> mGroupMap;
// Note that the constructor does not take a Cursor. This is done to avoid
// querying the database on the main thread.
public GroupsAdapter(Context context, GroupsListFragment glf,
int groupLayout, int childLayout, String[] groupFrom,
int[] groupTo, String[] childrenFrom, int[] childrenTo) {
super(context, null, groupLayout, groupFrom, groupTo, childLayout,
childrenFrom, childrenTo);
mActivity = (ContactManager) context;
mFragment = glf;
mGroupMap = new HashMap<Integer, Integer>();
}
@Override
protected Cursor getChildrenCursor(Cursor groupCursor) {
// Given the group, we return a cursor for all the children within that group
int groupPos = groupCursor.getPosition();
int groupId = groupCursor.getInt(groupCursor
.getColumnIndex(ContactsContract.Groups._ID));
Log.d(DEBUG_TAG, "getChildrenCursor() for groupPos " + groupPos);
Log.d(DEBUG_TAG, "getChildrenCursor() for groupId " + groupId);
mGroupMap.put(groupId, groupPos);
Loader loader = mActivity.getLoaderManager().getLoader(groupId);
if ( loader != null && !loader.isReset() ) {
mActivity.getLoaderManager().restartLoader(groupId, null, mFragment);
} else {
mActivity.getLoaderManager().initLoader(groupId, null, mFragment);
}
return null;
}
//Accessor method
public HashMap<Integer, Integer> getGroupMap() {
return mGroupMap;
}
}
