关于CursorWindowAllocatoinException有很多关于SO的问题:
> SQLite Android Database Cursor window allocation of 2048 kb failed
> Could not allocate CursorWindow
> Out of Memory when allocating cursors
> Android SQLite CursorWindowAllocationException crash
他们都建议游标在使用后必须关闭.但这并没有解决我的问题.这是我的代码:
String query = "select serial from tbl1 union select serial from tbl2 union select serial from tbl3"; SQLiteDatabase db = null; Cursor cur = null; try { SettingsDatabaseHelper dal = new SettingsDatabaseHelper( c); db = dal.getReadableDatabase(); cur = db.rawQuery(query,null); int numRows = cur.getCount(); if (numRows > 0) { cur.moveToFirst(); int serialIdx = cur.getColumnIndexOrThrow("serial"); for (boolean hasItem = cur.moveToFirst(); hasItem; hasItem = cur .moveToNext()) { String serial = cur.getString(serialIdx); if (Validator.getInstance().isValidSerial(serial)) serials.add(serial); } } } finally { if (cur != null) cur.close(); if (db != null) db.close(); }
我每隔几秒钟运行一次这个方法.半小时后,我在int numRows = cur.getCount()中得到CursorWindowAllocationException;然后我的服务停止.
由于我关闭游标,所以我的Helper类可能有问题.这是代码:
public class SettingsDatabaseHelper extends SQLiteOpenHelper { private static final String DATABASE_NAME = "mydb.db"; private static final int DATABASE_VERSION = 1; private static final String TBL_CREATE="create table..."; public SettingsDatabaseHelper(Context context) { super(context,DATABASE_NAME,null,DATABASE_VERSION); } @Override public void onCreate(SQLiteDatabase database) { database.execSQL(TBL_CREATE); } @Override public void onUpgrade(SQLiteDatabase db,int oldVersion,int newVersion) { onCreate(db); } }
如何防止这个异常被抛出?
解决方法
我正在从一个服务查询数据库.当我从一个活动中做到这一点,这个问题从未再次发生.
除了查询,我正在从同一个服务中的串行端口读取.也许这导致了这个问题.但是,当我使用活动而不是服务时,问题从未再次发生.