com.autentia.wuija.web.DownloadServlet.java Source code

Introduction

Here is the source code for com.autentia.wuija.web.DownloadServlet.java

Source

/**
 * Copyright 2008 Autentia Real Business Solutions S.L.
 * 
 * This file is part of Autentia WUIJA.
 * 
 * Autentia WUIJA is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, version 3 of the License.
 * 
 * Autentia WUIJA 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 Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with Autentia WUIJA. If not, see <http://www.gnu.org/licenses/>.
 */

package com.autentia.wuija.web;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * <p>
 * Implementacin de un servlet genrico que devuelve el contenido de un fichero que se ecuentre en el directorio de temporales al cliente. Dicho fichero puede haber 
 * sido generado previamente por un widget del tipo: {@link CsvExport}.
 * </p>
 * <p>
 * La clase {@link CsvExport} recibe el pagedDataTable a exportar, mediante una llamada al mtodo viewReport genera de
 * forma dinmica el contenido del fichero csv y lo escribe a fichero en el directorio temporal del servidor.
 * </p>
 * <p>
 * Esta clase se limita a obtener el fichero del directorio temporal y escribirlo en la salida del servlet junto con el
 * contentType y longitud concretos.
 * </p>
 * 
 * @author jmsanchez
 */
public class DownloadServlet extends HttpServlet {

    private static final long serialVersionUID = -3832768472985287410L;

    private static final String FILE_NAME = "FILE_NAME";

    private static final Log log = LogFactory.getLog(DownloadServlet.class);

    /**
     * Process POST request
     * 
     * @param request HTTP request
     * @param response HTTP response
     * @throws javax.servlet.ServletException
     */
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        super.doGet(request, response);
    }

    /**
     * Process GET request
     * 
     * @param request HTTP request
     * @param response HTTP response
     * @throws javax.servlet.ServletException
     */
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException {
        final String requestUri = request.getRequestURI();
        final String fileName = requestUri.substring(requestUri.lastIndexOf('/') + 1, requestUri.length());

        if (log.isTraceEnabled()) {
            log.trace("fileName='" + fileName + "'.");
        }

        if (fileName == null) {
            final String msg = "Filename not found in the requested URL.";
            log.error(msg);
            throw new ServletException(msg);
        }

        final StringBuilder tempFilePath = new StringBuilder(System.getProperty("java.io.tmpdir"));

        if (log.isTraceEnabled()) {
            log.trace("tempdir = " + tempFilePath);
        }

        if (tempFilePath.charAt(tempFilePath.length() - 1) != File.separatorChar) {
            tempFilePath.append(File.separatorChar);
        }

        tempFilePath.append(fileName);

        if (log.isTraceEnabled()) {
            log.trace("filePath = " + tempFilePath);
        }

        final File file = new File(tempFilePath.toString());
        file.deleteOnExit();

        String clientFileName = request.getHeader(FILE_NAME);
        if (clientFileName == null) {
            clientFileName = file.getName();
        }
        response.setHeader("Pragma", "no-cache");
        response.setHeader("Content-disposition", "attachment; filename=" + clientFileName);

        // XXX [wuija]: reemplazar por una librera de mimetypes
        if (clientFileName.toLowerCase().endsWith(".csv")) {
            response.setContentType("application/vnd.ms-excel");
        } else if (clientFileName.toLowerCase().endsWith(".zip")) {
            response.setContentType("application/zip");
        } else if (clientFileName.toLowerCase().endsWith(".pdf")) {
            response.setContentType("application/pdf");
        }
        response.setContentLength((int) file.length());

        try {
            int read = 0;
            final byte[] bytes = new byte[1024];
            final FileInputStream in = new FileInputStream(file);

            while ((read = in.read(bytes)) != -1) {
                response.getOutputStream().write(bytes, 0, read);
            }
            in.close();

            log.trace("The contents of the file have been written.");

            response.getOutputStream().flush();
            response.getOutputStream().close();
        } catch (IOException e) {
            final String msg = "Error writting the contents of the file.";
            log.error(msg);
            throw new ServletException(msg, e);
        }

        file.delete();
        log.trace("File='" + file + "' deleted.");

    }

}