Application: gvSIG desktop

/**

 * gvSIG. Desktop Geographic Information System.

 *

 * Copyright (C) 2007-2020 gvSIG Association.

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public License

 * as published by the Free Software Foundation; either version 3

 * of the License, or (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,

 * MA  02110-1301, USA.

 *

 * For any additional information, do not hesitate to contact us

 * at info AT gvsig.com, or visit our website www.gvsig.com.

 */

package org.gvsig.fmap.dal.store.jdbc2.spi.operations;

import java.io.IOException;

import java.sql.Blob;

import java.sql.Clob;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.sql.Statement;

import org.apache.commons.io.IOUtils;

import org.gvsig.expressionevaluator.ExpressionBuilder;

import org.gvsig.fmap.dal.SQLBuilder.SelectBuilder;

import org.gvsig.fmap.dal.exception.DataException;

import org.gvsig.fmap.dal.store.jdbc2.JDBCHelper;

import org.gvsig.fmap.dal.store.jdbc2.spi.JDBCSQLBuilderBase;

import org.gvsig.fmap.dal.store.jdbc.exception.JDBCSQLException;

import org.gvsig.fmap.dal.store.jdbc2.JDBCConnection;

import org.gvsig.fmap.dal.store.jdbc2.JDBCUtils;

import org.gvsig.fmap.dal.store.jdbc2.OperationsFactory.TableReference;

public class RetrieveValueOperation extends AbstractConnectionOperation {

    private final TableReference table;

    private final String filter;

    private final String order;

    private final String fieldname;

    public RetrieveValueOperation(

            JDBCHelper helper

        ) {

        this(helper, null, null, null, null);

    }

    public RetrieveValueOperation(

            JDBCHelper helper,

            TableReference table,

            String filter,

            String order,

            String fieldname

        ) {

        super(helper);

        this.table = table;

        this.filter = filter;

        this.order = order;

        this.fieldname = fieldname;

    }

    @Override

    public final Object perform(JDBCConnection conn) throws DataException {

        return this.retrieveValue(conn);

    }

    public String getSQL() {

        JDBCSQLBuilderBase sqlbuilder = this.createSQLBuilder();

        ExpressionBuilder expbuilder = sqlbuilder.expression();

        SelectBuilder select = sqlbuilder.select();

        select.column().name(this.fieldname);

        select.where().set(expbuilder.toValue(this.filter));

        // FIXME: Falta por ver de poner el order.

        select.from().table()

                .database(this.table.getDatabase())

                .schema(this.table.getSchema())

                .name(this.table.getTable());

        String sql = select.toString();

        return sql;

    }

    public Object retrieveValue(JDBCConnection conn) throws DataException {

        String sql = this.getSQL();

        Statement st = null;

        ResultSet rs = null;

        try {

            st = conn.createStatement();

            rs = JDBCUtils.executeQuery(st, sql);

            if (!rs.next()) {

                return null;

            }

            Object value = rs.getObject(1);

            if (value instanceof Blob) {

                Blob blob = (Blob) value;

                value = blob.getBytes(1, (int) blob.length());

                blob.free();

            } else if (value instanceof Clob) {

                Clob clob = (Clob) value;

                value = new String(IOUtils.toCharArray(clob.getCharacterStream()));

                clob.free();

            }            

            return value;

        } catch (SQLException ex) {

            throw new JDBCSQLException(ex,sql);

        } catch (IOException ex) {

            throw new JDBCSQLException(ex,sql);

        } finally {

            JDBCUtils.closeQuietly(st);

            JDBCUtils.closeQuietly(rs);

        }

    }

}