/*
* 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;
import com.dangdang.ddframe.rdb.sharding.merger.resultset.delegate.AbstractDelegateResultSet;
import lombok.Getter;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
/**
* 分片结果集集合.
*
* @author zhangliang
*/
@Getter
public final class ShardingResultSets {
private final List<ResultSet> resultSets;
private final Type type;
public ShardingResultSets(final List<ResultSet> resultSets) throws SQLException {
this.resultSets = filterResultSets(resultSets);
type = generateType();
}
private List<ResultSet> filterResultSets(final List<ResultSet> resultSets) throws SQLException {
List<ResultSet> result = new ArrayList<>(resultSets.size());
for (ResultSet each : resultSets) {
if (each.next()) {
result.add(new WrapperResultSet(each));
}
}
return result;
}
private Type generateType() {
if (this.resultSets.isEmpty()) {
return Type.EMPTY;
} else if (1 == this.resultSets.size()) {
return Type.SINGLE;
} else {
return Type.MULTIPLE;
}
}
enum Type {
EMPTY, SINGLE, MULTIPLE
}
private static final class WrapperResultSet extends AbstractDelegateResultSet {
private WrapperResultSet(final ResultSet resultSetWhenNextOnce) throws SQLException {
super(Collections.singletonList(resultSetWhenNextOnce));
}
@Override
protected boolean firstNext() throws SQLException {
return true;
}
@Override
protected boolean afterFirstNext() throws SQLException {
return getDelegate().next();
}
}
}