import org.sdnplatform.sync.internal.util.EmptyClosableIterator; //导入依赖的package包/类
@Override
public IClosableIterator<Entry<ByteArray, List<Versioned<byte[]>>>>
        entries() {
    PreparedStatement stmt = null;
    Connection dbConnection = null;
    try {
        // we never close this connection unless there's an error; 
        // it must be closed by the DbIterator
        dbConnection = getConnection();
        stmt = dbConnection.prepareStatement(getSql(SELECT_ALL));
        ResultSet rs = stmt.executeQuery();
        return new DbIterator(dbConnection, stmt, rs);                
    } catch (Exception e) {
        logger.error("Could not create iterator on data", e);
        try {
            cleanupSQL(dbConnection, stmt);
        } catch (Exception e2) {
            logger.error("Failed to clean up after error", e2);
        }
        return new EmptyClosableIterator<Entry<ByteArray,List<Versioned<byte[]>>>>();
    }
}
 

import org.sdnplatform.sync.internal.util.EmptyClosableIterator; //导入依赖的package包/类
@Override
public IClosableIterator<Entry<ByteArray, List<Versioned<byte[]>>>>
        entries() {
    PreparedStatement stmt = null;
    Connection dbConnection = null;
    try {
        // we never close this connection unless there's an error;
        // it must be closed by the DbIterator
        dbConnection = getConnection();
        stmt = dbConnection.prepareStatement(getSql(SELECT_ALL));
        ResultSet rs = stmt.executeQuery();
        return new DbIterator(dbConnection, stmt, rs);
    } catch (Exception e) {
        logger.error("Could not create iterator on data", e);
        try {
            cleanupSQL(dbConnection, stmt);
        } catch (Exception e2) {
            logger.error("Failed to clean up after error", e2);
        }
        return new EmptyClosableIterator<Entry<ByteArray,List<Versioned<byte[]>>>>();
    }
}