获取 java.lang.IllegalStateException：尝试重新打开已关闭的对象：在 Android 中使用光标时

Question

我正在使用 Cursor 从数据库获取数据（它是有关地图上叠加标记的信息）。我正在借助这些数据加载地图。通过 Cursor 与数据库的交互是在 asyncTask 中完成的。

现在这是我面临的问题。如果我在光标运行时按后退按钮来加载地图（即在 while 循环中加载覆盖标记的中间），我会收到此错误：

Caused by: java.lang.IllegalStateException: attempt to re-open an already-closed object: android.database.sqlite.SQLiteQuery (mSql = SELECT _id, category, latitude, longitude FROM node) 

这是它的完整跟踪：

12-21 11:11:30.173: E/AndroidRuntime(2824): FATAL EXCEPTION: AsyncTask #5
12-21 11:11:30.173: E/AndroidRuntime(2824): java.lang.RuntimeException: An error occured while executing doInBackground()
12-21 11:11:30.173: E/AndroidRuntime(2824):     at android.os.AsyncTask$3.done(AsyncTask.java:200)
12-21 11:11:30.173: E/AndroidRuntime(2824):     at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:273)
12-21 11:11:30.173: E/AndroidRuntime(2824):     at java.util.concurrent.FutureTask.setException(FutureTask.java:124)
12-21 11:11:30.173: E/AndroidRuntime(2824):     at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:307)
12-21 11:11:30.173: E/AndroidRuntime(2824):     at  java.util.concurrent.FutureTask.run(FutureTask.java:137)
12-21 11:11:30.173: E/AndroidRuntime(2824):     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1068)
12-21 11:11:30.173: E/AndroidRuntime(2824):     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:561)
12-21 11:11:30.173: E/AndroidRuntime(2824):     at java.lang.Thread.run(Thread.java:1102)
 12-21 11:11:30.173: E/AndroidRuntime(2824): Caused by: java.lang.IllegalStateException: attempt to re-open an already-closed object: android.database.sqlite.SQLiteQuery (mSql = SELECT _id, category, latitude, longitude FROM node) 
 12-21 11:11:30.173: E/AndroidRuntime(2824):    at android.database.sqlite.SQLiteClosable.acquireReference(SQLiteClosable.java:34)
12-21 11:11:30.173: E/AndroidRuntime(2824):     at android.database.sqlite.SQLiteQuery.fillWindow(SQLiteQuery.java:64)
12-21 11:11:30.173: E/AndroidRuntime(2824):     at android.database.sqlite.SQLiteCursor.fillWindow(SQLiteCursor.java:299)
12-21 11:11:30.173: E/AndroidRuntime(2824):     at android.database.sqlite.SQLiteCursor.onMove(SQLiteCursor.java:271)
12-21 11:11:30.173: E/AndroidRuntime(2824):     at android.database.AbstractCursor.moveToPosition(AbstractCursor.java:188)
12-21 11:11:30.173: E/AndroidRuntime(2824):     at android.database.AbstractCursor.moveToNext(AbstractCursor.java:256)
12-21 11:11:30.173: E/AndroidRuntime(2824):     at org.mid.kew.activities.MapPageActivity$MapLoadingAsyncTask.doInBackground(MapPageActivity.java:632)
12-21 11:11:30.173: E/AndroidRuntime(2824):     at org.mid.kew.activities.MapPageActivity$MapLoadingAsyncTask.doInBackground(MapPageActivity.java:1)
12-21 11:11:30.173: E/AndroidRuntime(2824):     at android.os.AsyncTask$2.call(AsyncTask.java:185)
12-21 11:11:30.173: E/AndroidRuntime(2824):     at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
12-21 11:11:30.173: E/AndroidRuntime(2824):     ... 4 more

这是我正在使用的代码的快照在 asyncTask 中的

DoInBackground 方法下的

openKewDataBase();
Cursor cursor = getCursorForOverLayIcons();
startManagingCursor(cursor);
cursor.moveToFirst();
while (!cursor.isAfterLast()) {
            ...

    cursor.moveToNext();
}

cursor.close();

onPostExecute 方法下，

....

closeKewDataBase();

我可以跟踪它在“cursor.moveToNext();”处的崩溃

Answer 1

当您使用 cursor.close() 手动关闭光标时，不应调用 startManagingCursor(cursor)。您需要选择其中之一。

当您在 AsyncTask 中执行此操作时，您几乎肯定不希望封闭的 Activity 为您管理光标，因为 AsyncTask可以比 Activity 更长久。所以只需手动执行即可。

（我假设 AsyncTask 是您的 Activity 的内部类。）