我的目标
我想批量插入多个记录到sqlite(事务性).
我的问题
我发现android.content.ContentResolver.bulkInsert(..)方法很有趣,但是javadoc说明：
This function make no guarantees about the atomicity of the insertions.
为什么android会提供一种瘫痪的方法？你能说出用于非原子插入的用例吗？我显然会覆盖ContentProvider.bulkInsert(..)以确保自己的原子性,所以我不确定为什么它是这样的短语.
解决方法
我们需要覆盖批量插入方法,如下所示……
public class Provider extends ContentProvider {
public static final Uri URI = Uri.parse("content://com.example.android.hoge/");
@Override
public String getType(Uri uri) {
return null;
}
@Override
public boolean onCreate() {
return false;
}
@Override
public Cursor query(Uri uri,String[] projection,String selection,String[] selectionArgs,String sortOrder) {
Helper helper = Helper.getInstance(getContext(),null);
sqliteDatabase sdb = helper.getReadableDatabase();
Cursor cursor = sdb.query(
Table.TABLENAME,new String[]{Table.ID,Table.DATA,Table.CREATED},selection,selectionArgs,null,sortOrder,null
);
return cursor;
}
@Override
public Uri insert(Uri uri,ContentValues values) {
Helper helper = Helper.getInstance(getContext(),null);
sqliteDatabase sdb = helper.getWritableDatabase();
sdb.insert(Table.TABLENAME,values);
getContext().getContentResolver().notifyChange(uri,null);
return uri;
}
/**
* super.bulkInsert is implemented the loop of insert without transaction
* So we need to override it and implement transaction.
*/
@Override
public int bulkInsert(Uri uri,ContentValues[] values) {
Helper helper = Helper.getInstance(getContext(),null);
sqliteDatabase sdb = helper.getWritableDatabase();
sdb.beginTransaction();
sqliteStatement stmt = sdb.compileStatement(
"INSERT INTO `" + Table.TABLENAME + "`(`" + Table.DATA + "`,`" + Table.CREATED + "`) VALUES (?,?);"
);
int length = values.length;
for(int i = 0; i < length; i++){
stmt.bindString(1,values[i].getAsString(Table.DATA));
stmt.bindLong(2,values[i].getAsLong(Table.CREATED));
stmt.executeInsert();
}
sdb.setTransactionSuccessful();
sdb.endTransaction();
return length;
}
@Override
public int update(Uri uri,ContentValues values,String[] selectionArgs) {
Helper helper = Helper.getInstance(getContext(),null);
sqliteDatabase sdb = helper.getWritableDatabase();
int rows = sdb.update(Table.TABLENAME,values,selectionArgs);
getContext().getContentResolver().notifyChange(uri,null);
return rows;
}
@Override
public int delete(Uri uri,null);
sqliteDatabase sdb = helper.getWritableDatabase();
int rows = sdb.delete(Table.TABLENAME,null);
return rows;
}
private static class Helper extends sqliteOpenHelper {
static Helper INSTANCE = null;
private Helper(Context context,CursorFactory factory) {
super(context,Table.FILENAME,factory,Table.VERSION);
}
public static Helper getInstance(Context context,CursorFactory factory) {
if (INSTANCE == null) {
INSTANCE = new Helper(context,factory);
}
return INSTANCE;
}
@Override
public void onCreate(sqliteDatabase db) {
db.execsql(
"CREATE TABLE `" + Table.TABLENAME + "`(" +
" `" + Table.ID + "` INTEGER PRIMARY KEY AUTOINCREMENT," +
" `" + Table.CREATED + "` INTEGER," +
" `" + Table.DATA + "` TEXT" +
");"
);
}
@Override
public void onUpgrade(sqliteDatabase db,int oldVersion,int newVersion) {
}
}
}
