ca.travelagency.persistence.query.QuerySQL.java Source code

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Here is the source code for ca.travelagency.persistence.query.QuerySQL.java

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/**
 *    Copyright (C) 2010 - 2014 VREM Software Development <VREMSoftwareDevelopment@gmail.com>
 *
 *    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 ca.travelagency.persistence.query;

import java.util.List;

import javax.persistence.EntityManager;
import javax.persistence.Query;

import org.apache.commons.lang3.Validate;

public abstract class QuerySQL {
    public static QuerySQL count(Criteria criteria, EntityManager entityManager) {
        return new QuerySQL(criteria, entityManager) {
            @Override
            protected String sqlAsString() {
                return SELECT + COUNT_START + simpleName + COUNT_END + from() + where();
            }
        };
    }

    public static QuerySQL find(Criteria criteria, EntityManager entityManager) {
        return new QuerySQL(criteria, entityManager) {
            @Override
            protected String sqlAsString() {
                return SELECT + DISTINCT + simpleName + from() + where() + orderBy();
            }

            @Override
            protected void addLimits(Query query) {
                if (criteria.getCount() != 0) {
                    // FIXME JPA Query uses int we use long
                    query.setFirstResult((int) criteria.getOffset());
                    query.setMaxResults((int) criteria.getCount());
                }
            }
        };
    }

    public static QuerySQL groupBy(Criteria criteria, EntityManager entityManager) {
        return new QuerySQL(criteria, entityManager) {
            @Override
            protected String sqlAsString() {
                String groupBy = criteria.getGroupBy();
                Validate.notBlank(groupBy, "GroupBy query requires group by to be specified");
                return SELECT + DISTINCT + simpleName + Condition.SEPARATOR + groupBy + from() + where() + groupBy()
                        + orderBy();
            }

            @Override
            protected void addLimits(Query query) {
                if (criteria.getCount() != 0) {
                    // FIXME JPA Query uses int we use long
                    query.setMaxResults((int) criteria.getCount());
                }
            }
        };
    }

    private static final String SELECT = "SELECT ";
    private static final String DISTINCT = "DISTINCT ";
    private static final String FROM = " FROM ";
    private static final String COUNT_START = "COUNT(" + DISTINCT;
    private static final String COUNT_END = ")";

    protected Criteria criteria;
    protected String simpleName;
    private EntityManager entityManager;

    private QuerySQL(Criteria criteria, EntityManager entityManager) {
        Validate.notNull(criteria);
        Validate.notNull(entityManager);
        this.criteria = criteria;
        this.simpleName = criteria.getClazz().getSimpleName();
        this.entityManager = entityManager;
    }

    protected String from() {
        return FROM + criteria.getClazz().getName() + " " + simpleName + criteria.from(simpleName);
    }

    protected String where() {
        return criteria.where(simpleName).getWhereAsSql();
    }

    protected String orderBy() {
        return criteria.getOrderByAsSql(simpleName);
    }

    protected String groupBy() {
        return criteria.getGroupByAsSql(simpleName);
    }

    public Query makeQuery() {
        String sqlAsString = sqlAsString();
        Query query = entityManager.createQuery(sqlAsString);
        addLimits(query);
        addParameters(query);
        //      displaySql();
        return query;
    }

    void displaySql() {
        System.out.println("SQL:[" + sqlAsString() + "]");
        List<Object> parameters = criteria.where(simpleName).getParameters();
        int index = 0;
        System.out.print("PARAMETERS:[");
        for (Object parameter : parameters) {
            System.out.print("" + index + ":" + parameter + " ");
        }
        System.out.println("]");
    }

    protected abstract String sqlAsString();

    protected void addLimits(Query query) {
    }

    private void addParameters(Query query) {
        Where where = criteria.where(simpleName);
        List<Object> parameters = where.getParameters();
        int index = 0;
        for (Object parameter : parameters) {
            query.setParameter(index++, parameter);
        }
    }

}