/*
* Copyright 1999-2015 dangdang.com.
* <p>
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
* </p>
*/
package com.dangdang.ddframe.rdb.sharding.merger.pipeline.coupling;
import com.dangdang.ddframe.rdb.sharding.merger.ResultSetMergeContext;
import com.dangdang.ddframe.rdb.sharding.merger.resultset.memory.AbstractMemoryResultSet;
import com.dangdang.ddframe.rdb.sharding.merger.resultset.memory.row.GroupByResultSetRow;
import com.dangdang.ddframe.rdb.sharding.merger.resultset.memory.row.ResultSetRow;
import com.dangdang.ddframe.rdb.sharding.parser.result.merger.AggregationColumn;
import com.dangdang.ddframe.rdb.sharding.parser.result.merger.GroupByColumn;
import com.google.common.base.Optional;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Collections;
import java.util.List;
/**
* 分组的连接结果集.
*
* @author gaohongtao
* @author zhangliang
*/
public final class GroupByCouplingResultSet extends AbstractMemoryResultSet {
private final List<GroupByColumn> groupByColumns;
private final List<AggregationColumn> aggregationColumns;
private ResultSet resultSet;
private boolean hasNext;
public GroupByCouplingResultSet(final ResultSet resultSet, final ResultSetMergeContext resultSetMergeContext) throws SQLException {
super(Collections.singletonList(resultSet));
groupByColumns = resultSetMergeContext.getMergeContext().getGroupByColumns();
aggregationColumns = resultSetMergeContext.getMergeContext().getAggregationColumns();
}
@Override
protected void initRows(final List<ResultSet> resultSets) throws SQLException {
resultSet = resultSets.get(0);
hasNext = resultSet.next();
}
@Override
protected Optional<? extends ResultSetRow> nextRow() throws SQLException {
if (!hasNext) {
return Optional.absent();
}
GroupByResultSetRow result = new GroupByResultSetRow(resultSet, groupByColumns, aggregationColumns);
List<Object> groupByValues = result.getGroupByValues();
while (hasNext && (groupByColumns.isEmpty() || groupByValues.equals(result.getGroupByValues()))) {
result.aggregate();
hasNext = resultSet.next();
}
result.generateResult();
return Optional.of(result);
}
}