org.springframework.batch.item.database.support.MySqlPagingQueryProvider.java Source code

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Here is the source code for org.springframework.batch.item.database.support.MySqlPagingQueryProvider.java

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/*
 * 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 org.springframework.batch.item.database.PagingQueryProvider;
import org.springframework.util.StringUtils;

/**
 * MySQL implementation of a {@link PagingQueryProvider} using database specific features.
 *
 * @author Thomas Risberg
 * @author Michael Minella
 * @since 2.0
 */
public class MySqlPagingQueryProvider extends AbstractSqlPagingQueryProvider {

    @Override
    public String generateFirstPageQuery(int pageSize) {
        return SqlPagingQueryUtils.generateLimitSqlQuery(this, false, buildLimitClause(pageSize));
    }

    @Override
    public String generateRemainingPagesQuery(int pageSize) {
        if (StringUtils.hasText(getGroupClause())) {
            return SqlPagingQueryUtils.generateLimitGroupedSqlQuery(this, true, buildLimitClause(pageSize));
        } else {
            return SqlPagingQueryUtils.generateLimitSqlQuery(this, true, buildLimitClause(pageSize));
        }
    }

    private String buildLimitClause(int pageSize) {
        return new StringBuilder().append("LIMIT ").append(pageSize).toString();
    }

    @Override
    public String generateJumpToItemQuery(int itemIndex, int pageSize) {
        int page = itemIndex / pageSize;
        int offset = (page * pageSize) - 1;
        offset = offset < 0 ? 0 : offset;

        String limitClause = new StringBuilder().append("LIMIT ").append(offset).append(", 1").toString();
        return SqlPagingQueryUtils.generateLimitJumpToQuery(this, limitClause);
    }

}