spring-batch OraclePagingQueryProvider 源码
spring-batch OraclePagingQueryProvider 代码
文件路径：/spring-batch-infrastructure/src/main/java/org/springframework/batch/item/database/support/OraclePagingQueryProvider.java
/*
* Copyright 2006-2012 the original author or authors.
*
* 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
*
* https://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.
*/
package org.springframework.batch.item.database.support;
import java.util.Map;
import org.springframework.batch.item.database.Order;
/**
* Oracle implementation of a
* {@link org.springframework.batch.item.database.PagingQueryProvider} using database
* specific features.
*
* @author Thomas Risberg
* @author Michael Minella
* @since 2.0
*/
public class OraclePagingQueryProvider extends AbstractSqlPagingQueryProvider {
@Override
public String generateFirstPageQuery(int pageSize) {
return SqlPagingQueryUtils.generateRowNumSqlQuery(this, false, buildRowNumClause(pageSize));
}
@Override
public String generateRemainingPagesQuery(int pageSize) {
return SqlPagingQueryUtils.generateRowNumSqlQuery(this, true, buildRowNumClause(pageSize));
}
@Override
public String generateJumpToItemQuery(int itemIndex, int pageSize) {
int page = itemIndex / pageSize;
int offset = (page * pageSize);
offset = offset == 0 ? 1 : offset;
String sortKeySelect = this.getSortKeySelect();
return SqlPagingQueryUtils.generateRowNumSqlQueryWithNesting(this, sortKeySelect, sortKeySelect, false,
"TMP_ROW_NUM = " + offset);
}
private String getSortKeySelect() {
StringBuilder sql = new StringBuilder();
String prefix = "";
for (Map.Entry<String, Order> sortKey : this.getSortKeys().entrySet()) {
sql.append(prefix);
prefix = ", ";
sql.append(sortKey.getKey());
}
return sql.toString();
}
private String buildRowNumClause(int pageSize) {
return new StringBuilder().append("ROWNUM <= ").append(pageSize).toString();
}
}
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