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Spring Data Relational support
/*
* Copyright 2019-2023 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.data.relational.core.dialect;
import java.util.Collections;
import java.util.Set;
import org.springframework.data.relational.core.sql.IdentifierProcessing;
import org.springframework.data.relational.core.sql.IdentifierProcessing.LetterCasing;
import org.springframework.data.relational.core.sql.IdentifierProcessing.Quoting;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;
/**
* An SQL dialect for H2.
*
* @author Mark Paluch
* @author Myeonghyeon Lee
* @author Christph Strobl
* @since 2.0
*/
public class H2Dialect extends AbstractDialect {
/**
* Singleton instance.
*/
public static final H2Dialect INSTANCE = new H2Dialect();
protected H2Dialect() {}
private static final LimitClause LIMIT_CLAUSE = new LimitClause() {
/*
* (non-Javadoc)
* @see org.springframework.data.relational.core.dialect.LimitClause#getLimit(long)
*/
@Override
public String getLimit(long limit) {
return "LIMIT " + limit;
}
/*
* (non-Javadoc)
* @see org.springframework.data.relational.core.dialect.LimitClause#getOffset(long)
*/
@Override
public String getOffset(long offset) {
return "OFFSET " + offset;
}
/*
* (non-Javadoc)
* @see org.springframework.data.relational.core.dialect.LimitClause#getClause(long, long)
*/
@Override
public String getLimitOffset(long limit, long offset) {
return String.format("OFFSET %d ROWS FETCH FIRST %d ROWS ONLY", offset, limit);
}
/*
* (non-Javadoc)
* @see org.springframework.data.relational.core.dialect.LimitClause#getClausePosition()
*/
@Override
public Position getClausePosition() {
return Position.AFTER_ORDER_BY;
}
};
private final H2ArrayColumns ARRAY_COLUMNS = new H2ArrayColumns();
/*
* (non-Javadoc)
* @see org.springframework.data.relational.core.dialect.Dialect#limit()
*/
@Override
public LimitClause limit() {
return LIMIT_CLAUSE;
}
/*
* (non-Javadoc)
* @see org.springframework.data.relational.core.dialect.Dialect#lock()
*/
@Override
public LockClause lock() {
return AnsiDialect.LOCK_CLAUSE;
}
/*
* (non-Javadoc)
* @see org.springframework.data.relational.core.dialect.Dialect#getArraySupport()
*/
@Override
public ArrayColumns getArraySupport() {
return ARRAY_COLUMNS;
}
static class H2ArrayColumns implements ArrayColumns {
/*
* (non-Javadoc)
* @see org.springframework.data.relational.core.dialect.ArrayColumns#isSupported()
*/
@Override
public boolean isSupported() {
return true;
}
/*
* (non-Javadoc)
* @see org.springframework.data.relational.core.dialect.ArrayColumns#getArrayType(java.lang.Class)
*/
@Override
public Class getArrayType(Class userType) {
Assert.notNull(userType, "Array component type must not be null");
return ClassUtils.resolvePrimitiveIfNecessary(userType);
}
}
/*
* (non-Javadoc)
* @see org.springframework.data.relational.core.dialect.Dialect#getIdentifierProcessing()
*/
@Override
public IdentifierProcessing getIdentifierProcessing() {
return IdentifierProcessing.create(Quoting.ANSI, LetterCasing.UPPER_CASE);
}
/*
* (non-Javadoc)
* @see org.springframework.data.relational.core.dialect.Dialect#simpleTypes()
*/
@Override
public Set> simpleTypes() {
if (!ClassUtils.isPresent("org.h2.api.TimestampWithTimeZone", getClass().getClassLoader())) {
return Collections.emptySet();
}
try {
return Collections.singleton(ClassUtils.forName("org.h2.api.TimestampWithTimeZone", getClass().getClassLoader()));
} catch (ClassNotFoundException e) {
throw new IllegalStateException(e);
}
}
}