at.mukprojects.exclycore.dao.XLSXWriter.java Source code

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Here is the source code for at.mukprojects.exclycore.dao.XLSXWriter.java

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/** 
 * This code is copyright (c) Mathias Markl 2015
 * 
 * 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, see <http://www.gnu.org/licenses/>.
 */

package at.mukprojects.exclycore.dao;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;

import org.apache.poi.openxml4j.exceptions.InvalidFormatException;
import org.apache.poi.ss.usermodel.WorkbookFactory;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Logger is an abstract helper class. It can be extended by any other class to
 * create or extends Excel (.xlsx) files.
 * 
 * @author Mathias Markl
 */
public abstract class XLSXWriter {
    private static final Logger log = LoggerFactory.getLogger(XLSXWriter.class);

    private FileOutputStream outputStream;
    private XSSFWorkbook outputWorkbook;
    private File output;
    private File tempOutput;

    /**
     * This method lets you create the workbook. The workbook can be used to
     * create or edit Excel content. After finishing the writing process its
     * necessary to close the workbook with the the method called closeWorkbook.
     * 
     * @param output
     *            The output file.
     * @param add
     *            Set this parameter to tell the writer if you want to append
     *            the content to an existing file or if you want to create a
     *            completely new file.
     * @return Returns the workbook.
     * @throws IOException
     *             The Exception is thrown if an error occurs.
     */
    protected XSSFWorkbook createWorkbook(File output, boolean add) throws IOException {
        log.info("Workbook gets created...");

        this.output = output;

        if (add) {
            log.info("The content will be appended to the existing file.");

            if (output.exists() && output.getName().endsWith("xlsx")) {
                try {
                    outputWorkbook = (XSSFWorkbook) WorkbookFactory.create(output);
                } catch (InvalidFormatException e) {
                    log.error("The Writer is unable to open" + " the existing Workbook.", e);
                    throw new IOException("The Writer is unable to open" + " the existing Workbook.", e);
                }
                tempOutput = new File(output.getAbsolutePath() + ".temp");
                outputStream = new FileOutputStream(tempOutput);
            } else {
                outputStream = new FileOutputStream(output);
                outputWorkbook = new XSSFWorkbook();
            }
        } else {
            log.info("The content will be written in a new file.");

            outputStream = new FileOutputStream(output);
            outputWorkbook = new XSSFWorkbook();
        }

        return outputWorkbook;
    }

    /**
     * Closes the workbook and cleans up all the used resources.
     * 
     * @throws IOException
     *             The Exception is thrown if an error occurs.
     */
    protected void closeWorkbook() throws IOException {
        if (outputWorkbook != null) {
            outputWorkbook.write(outputStream);
            if (tempOutput != null) {
                output.delete();
                tempOutput.renameTo(output);
                tempOutput.delete();
            }
            outputWorkbook.close();
        }
        if (outputStream != null) {
            outputStream.close();
        }
    }
}