Introduced QueryEnhancer API.

Queries often need to be enhanced for example with an "order by" or a "where" clause and `QueryEnhancer` provides a simple inferface that handles all the enhancements. Since native queries can be parsed and processed more efficiently with JSqlParser there is a `QueryEnhancer` implementation using JSqlParser. On the other side there is a default implementation using the custom written parser `DefaultQueryEnhancer`. If a given query cannot be identified as a native one the `DefaultQueryEnhancer` is used.

Related tickets spring-projects#2409

Author: DiegoKrupitza

src/main/java/org/springframework/data/jpa/repository/query/AbstractStringBasedJpaQuery.java

@@ -86,7 +86,8 @@ public AbstractStringBasedJpaQuery(JpaQueryMethod method, EntityManager em, Stri
 	@Override
 	public Query doCreateQuery(JpaParametersParameterAccessor accessor) {
 
-		String sortedQueryString = QueryUtils.applySorting(query, accessor.getSort(), query.getAlias());
+		String sortedQueryString = QueryEnhancerFactory.forQuery(query) //
+				.applySorting(query, accessor.getSort(), query.getAlias());
 		ResultProcessor processor = getQueryMethod().getResultProcessor().withDynamicProjection(accessor);
 
 		Query query = createJpaQuery(sortedQueryString, processor.getReturnedType());

src/main/java/org/springframework/data/jpa/repository/query/DefaultQueryEnhancer.java

@@ -0,0 +1,56 @@
+/*
+ * Copyright 2022 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.jpa.repository.query;
+
+import org.springframework.data.domain.Sort;
+
+/**
+ * The implementation of {@link QueryEnhancer} using {@link QueryUtils}.
+ *
+ * @author Diego Krupitza
+ */
+public class DefaultQueryEnhancer implements QueryEnhancer {
+
+	@Override
+	public String getExistsQueryString(String entityName, String countQueryPlaceHolder, Iterable<String> idAttributes) {
+		return QueryUtils.getExistsQueryString(entityName, countQueryPlaceHolder, idAttributes);
+	}
+
+	@Override
+	public String getQueryString(String template, String entityName) {
+		return QueryUtils.getQueryString(template, entityName);
+	}
+
+	@Override
+	public String applySorting(DeclaredQuery query, Sort sort, String alias) {
+		return QueryUtils.applySorting(query.getQueryString(), sort, alias);
+	}
+
+	@Override
+	public String detectAlias(DeclaredQuery query) {
+		return QueryUtils.detectAlias(query.getQueryString());
+	}
+
+	@Override
+	public String createCountQueryFor(DeclaredQuery originalQuery, String countProjection) {
+		return QueryUtils.createCountQueryFor(originalQuery.getQueryString(), countProjection);
+	}
+
+	@Override
+	public String getProjection(DeclaredQuery query) {
+		return QueryUtils.getProjection(query.getQueryString());
+	}
+}