com.blazebit.persistence.impl.dialect.AbstractDbmsLimitHandler Maven / Gradle / Ivy
/*
* Copyright 2014 - 2019 Blazebit.
*
* 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.
*/
package com.blazebit.persistence.impl.dialect;
import com.blazebit.persistence.spi.DbmsLimitHandler;
import java.sql.PreparedStatement;
import java.sql.SQLException;
/**
* @author Christian Beikov
* @since 1.2.0
*/
public abstract class AbstractDbmsLimitHandler implements DbmsLimitHandler {
private final int length;
/**
* @param length The expected maximum length of the string representation for the LIMIT/OFFSET SQL
*/
public AbstractDbmsLimitHandler(int length) {
this.length = length;
}
@Override
public boolean supportsLimit() {
return true;
}
@Override
public boolean supportsLimitOffset() {
return true;
}
@Override
public boolean limitIncludesOffset() {
return false;
}
/**
* Returns whether the dbms supports parameters for LIMIT and OFFSET via prepared statements.
*
* @return True if parameters allowed, otherwise false
*/
protected abstract boolean supportsVariableLimit();
@Override
public String applySql(String sql, boolean isSubquery, Integer limit, Integer offset) {
if (limit == null && offset == null) {
return sql;
}
StringBuilder sb = new StringBuilder(sql.length() + length);
sb.append(sql);
if (supportsVariableLimit()) {
applySql(sb, isSubquery, limit == null ? null : "?", offset == null ? null : "?");
} else {
if (limitIncludesOffset() && offset != null && limit != null) {
applySql(sb, isSubquery, Integer.toString(limit + offset), offset.toString());
} else {
applySql(sb, isSubquery, limit == null ? null : limit.toString(), offset == null ? null : offset.toString());
}
}
return sb.toString();
}
@Override
public String applySqlInlined(String sql, boolean isSubquery, Integer limit, Integer offset) {
if (limit == null && offset == null) {
return sql;
}
StringBuilder sb = new StringBuilder(sql.length() + length);
sb.append(sql);
if (limitIncludesOffset() && offset != null && limit != null) {
applySql(sb, isSubquery, Integer.toString(limit + offset), offset.toString());
} else {
applySql(sb, isSubquery, limit == null ? null : limit.toString(), offset == null ? null : offset.toString());
}
return sb.toString();
}
@Override
public int bindLimitParametersAtStartOfQuery(Integer limit, Integer offset, PreparedStatement statement, int index) throws SQLException {
return 0;
}
@Override
public void setMaxRows(Integer limit, Integer offset, PreparedStatement statement) throws SQLException {
}
}