Java tutorial
/* * Copyright 2012-2019 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.gemfire.repository.query; import org.apache.geode.cache.Region; import org.springframework.data.gemfire.mapping.GemfirePersistentEntity; import org.springframework.data.gemfire.repository.query.support.OqlKeyword; import org.springframework.data.repository.query.parser.PartTree; import org.springframework.util.Assert; /** * The QueryBuilder class is used to build a {@link QueryString}. * * @author Oliver Gierke * @author David Turanski * @author John Blum * @see org.springframework.data.gemfire.repository.query.QueryString */ class QueryBuilder { static final String DEFAULT_ALIAS = "x"; static final String SELECT_OQL_TEMPLATE = "SELECT %1$s * FROM /%2$s %3$s"; static final String WHERE_CLAUSE_TEMPLATE = "%1$s WHERE %2$s"; private final String query; /* (non-Javadoc) */ static String asQuery(GemfirePersistentEntity<?> entity, PartTree tree) { return String.format(SELECT_OQL_TEMPLATE, tree.isDistinct() ? OqlKeyword.DISTINCT : "", entity.getRegionName(), DEFAULT_ALIAS).replaceAll("\\s{2,}", " "); } /* (non-Javadoc) */ static String validateQuery(String query) { Assert.hasText(query, "Query is required"); return query; } /** * Constructs a new instance of {@link QueryBuilder} initialized with the given {@link String query}. * * @param query {@link String} containing the base {@link String OQL query}. * @see #validateQuery(String) */ public QueryBuilder(String query) { this.query = validateQuery(query); } /** * Constructs a new instance of {@link QueryBuilder} initialized with the given {@link GemfirePersistentEntity} * and {@link PartTree} used to determine the {@link Region} to query and whether the query * should capture unique results. * * @param entity {@link GemfirePersistentEntity} used to determine the {@link Region} to query. * @param tree {@link PartTree} containing parts of the OQL Query for determining things like uniqueness. * @see org.springframework.data.gemfire.mapping.GemfirePersistentEntity * @see org.springframework.data.repository.query.parser.PartTree * @see #QueryBuilder(String) */ public QueryBuilder(GemfirePersistentEntity<?> entity, PartTree tree) { this(asQuery(entity, tree)); } /** * Constructs a {@link QueryString} with the given {@link Predicate}. * * @param predicate {@link Predicate} to append to the query. * @return a {@link QueryString} with the base OQL query and {@link Predicate}. * @see org.springframework.data.gemfire.repository.query.Predicate * @see #withPredicate(String, Predicate) */ public QueryString create(Predicate predicate) { return new QueryString(withPredicate(this.query, predicate)); } /** * Appends the given {@link Predicate} to the given {@code query} {@link String}. * * @param query {@link String} containing the query. * @param predicate {@link Predicate} to append to the query. * @return a {@link String} containing the query with the {@link Predicate} appended, * or just a {@link String} containing the query if the {@link Predicate} is {@literal null}. * @see org.springframework.data.gemfire.repository.query.Predicate */ protected String withPredicate(String query, Predicate predicate) { return predicate != null ? String.format(WHERE_CLAUSE_TEMPLATE, query, predicate.toString(DEFAULT_ALIAS)) : query; } /* * (non-Javadoc) * @see java.lang.Object#toString() */ @Override public String toString() { return this.query; } }