Android Query & managedQuery

今天说一下以下两种方式query数据：

 

 

 

 Cursor c1 = mContext.getContentResolver().query(uri, projection, selection, selectionArgs, sortOrder);

 Cursor c2 = mActivity.managedQuery(uri, projection, selection, sortOrder);

 

 

 

使用方法一：若将Cursor c1数据放入Adapter 中,如getView() 调用加载数据，需在此Adapter对应Activity生命周期中，对Cursor进行控制，尤其要注意c1.close()的处理，否则会在反复出现如下Exception.

 

 E/Cursor  ( 1384): Finalizing a Cursor that has not been deactivated or closed. database = /data/data/xx/databases/xx.db, table = xx, query = SELECT xx
 E/Cursor  ( 1384): android.database.sqlite.DatabaseObjectNotClosedException: Application did not close the cursor or database object that was opened here
 E/Cursor  ( 1384):  at android.database.sqlite.SQLiteCursor.<init>(SQLiteCursor.java:210)
 E/Cursor  ( 1384):  at android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:53)
 E/Cursor  ( 1384):  at android.database.sqlite.SQLiteDatabase.rawQueryWithFactory(SQLiteDatabase.java:1345)
 E/Cursor  ( 1384):  at android.database.sqlite.SQLiteDatabase.queryWithFactory(SQLiteDatabase.java:1229)
 E/Cursor  ( 1384):  at android.database.sqlite.SQLiteDatabase.query(SQLiteDatabase.java:1184)
 E/Cursor  ( 1384):  at android.database.sqlite.SQLiteDatabase.query(SQLiteDatabase.java:1301)

 使用方法二：Cursor c2 会随着Activity生命周期的变化，让Activity去控制c2的生命周期，所以不用太但心cursor是否被close,是否requery.

参考:http://consuela-zhao.iteye.com/blog/961617