org.centralperf.helper.view.AbstractPOIExcelView.java Source code

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Here is the source code for org.centralperf.helper.view.AbstractPOIExcelView.java

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/*
 * Copyright (C) 2014  The Central Perf authors
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package org.centralperf.helper.view;

import java.util.Locale;
import java.util.Map;

import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.poi.ss.usermodel.Workbook;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
import org.springframework.core.io.Resource;
import org.springframework.core.io.support.LocalizedResourceHelper;
import org.springframework.web.servlet.support.RequestContextUtils;
import org.springframework.web.servlet.view.AbstractView;

/**
 * This view allows to generate Excel OOXML like files (.XLSX) and "old" Excel files (.XLS) as Spring MVC views<br/>
 * Concrete class must implement this abstract class to provide Excel based views.<br/>
 * Document can be build on templates, provided by their URL.
 */
public abstract class AbstractPOIExcelView extends AbstractView {

    /** The content type for an Excel response */
    private static final String CONTENT_TYPE_XLSX = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";
    private static final String CONTENT_TYPE_XLS = "application/vnd.ms-excel";
    private static final String EXTENSION = ".xlsx";

    private String url;

    public String getUrl() {
        return url;
    }

    public void setUrl(String url) {
        this.url = url;
    }

    /**
     * Default constructor
     */
    public AbstractPOIExcelView() {
    }

    @Override
    protected boolean generatesDownloadContent() {
        return true;
    }

    @Override
    protected final void renderMergedOutputModel(Map<String, Object> model, HttpServletRequest request,
            HttpServletResponse response) throws Exception {

        Workbook workbook = null;

        if (url != null) {
            workbook = getTemplateSource(url, request);
        } else {
            workbook = createWorkbook();
        }

        if (workbook instanceof XSSFWorkbook) {
            setContentType(CONTENT_TYPE_XLSX);
        } else {
            setContentType(CONTENT_TYPE_XLS);
        }

        buildExcelDocument(model, workbook, request, response);

        // Set the content type.
        response.setContentType(getContentType());

        // Flush byte array to servlet output stream.
        ServletOutputStream out = response.getOutputStream();
        out.flush();
        // Have to catch exception because of thise bug : https://issues.apache.org/bugzilla/show_bug.cgi?id=49940
        try {
            workbook.write(out);
        } catch (org.apache.xmlbeans.impl.values.XmlValueDisconnectedException disconnectedException) {
            // Do nothing... In fact, it's only a bug...
        }
        out.flush();

        // Don't close the stream - we didn't open it, so let the container
        // handle it.
        // http://stackoverflow.com/questions/1829784/should-i-close-the-servlet-outputstream
    }

    /**
    * Creates the workbook from an existing XLS document.
    * @param url the URL of the Excel template without localization part nor extension
    * @param request current HTTP request
    * @return the HSSFWorkbook
    * @throws Exception in case of failure
    */
    protected Workbook getTemplateSource(String url, HttpServletRequest request) throws Exception {
        LocalizedResourceHelper helper = new LocalizedResourceHelper(getApplicationContext());
        Locale userLocale = RequestContextUtils.getLocale(request);
        Resource inputFile = helper.findLocalizedResource(url, EXTENSION, userLocale);

        // Create the Excel document from the source.
        if (logger.isDebugEnabled()) {
            logger.debug("Loading Excel workbook from " + inputFile);
        }
        return new XSSFWorkbook(inputFile.getInputStream());
    }

    /**
     * Subclasses must implement this method to create an Excel Workbook.
     * HSSFWorkbook and XSSFWorkbook are both possible formats.
     */
    protected abstract Workbook createWorkbook();

    /**
     * Subclasses must implement this method to create an Excel HSSFWorkbook
     * document, given the model.
     * 
     * @param model
     *            the model Map
     * @param workbook
     *            the Excel workbook to complete
     * @param request
     *            in case we need locale etc. Shouldn't look at attributes.
     * @param response
     *            in case we need to set cookies. Shouldn't write to it.
     */
    protected abstract void buildExcelDocument(Map<String, Object> model, Workbook workbook,
            HttpServletRequest request, HttpServletResponse response) throws Exception;

}