de.fau.amos.FileDownload.java Source code

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Here is the source code for de.fau.amos.FileDownload.java

Source

/*
 * Copyright (c) 2014 by Sven Huprich, Dimitry Abb, Jakob Hbler, Cindy Wiebe, Ferdinand Niedermayer, Dirk Riehle, http://dirkriehle.com
 *
 * This file is part of the Green Energy Cockpit for the AMOS Project.
 *
 * 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 de.fau.amos;

import java.io.*;
import java.util.ArrayList;
import java.util.List;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;

@WebServlet("/FileDownload")
public class FileDownload extends HttpServlet {

    private static final long serialVersionUID = 1L;

    public FileDownload() {
        super();
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doPost(request, response);
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        String fileName = request.getParameter("downloadFileName");

        //creates a file containing the values of the requested SQL query 
        System.out.println("create file " + fileName + "");
        ArrayList<ArrayList<String>> data = SQL.query("select * from plants");
        createCsvFile(data, fileName);

        File file = new File(System.getProperty("userdir.location"), fileName);

        if (fileName == null || !file.exists()) {
            request.getRequestDispatcher("/intern/funktion3.jsp").forward(request, response);
            return;
        }

        response.setHeader("Content-Length", String.valueOf(file.length()));
        response.setHeader("Content-Disposition", "attachment; filename=\"" + fileName + "\"");

        InputStream input = new BufferedInputStream(new FileInputStream(file), 1024 * 10);
        OutputStream output = new BufferedOutputStream(response.getOutputStream(), 1024 * 10);

        byte[] buffer = new byte[1024 * 10];
        int length;
        while ((length = input.read(buffer)) > 0) {
            output.write(buffer, 0, length);
        }

        output.flush();
        output.close();
        input.close();

    }

    /**
     * Creates a .csv file containing the data of the passed "ArrayList<ArrayList<String>> data" and saves it into the "userdir.location" directory
     * @param data
     * @param fileName
     */
    private static void createCsvFile(ArrayList<ArrayList<String>> data, String fileName) {

        try {
            String lines = "";

            //using Buffered Writer to write a file into the "userdir.location" directory
            BufferedWriter bw = new BufferedWriter(
                    new FileWriter(new File(System.getProperty("userdir.location"), fileName)));

            //every single value will be written down into the file separated by a semicolon
            for (int i = 0; i < data.size(); i++) {
                for (int j = 0; j < data.get(i).size(); j++) {
                    lines = data.get(i).get(j) + "; ";
                    bw.write(lines);
                }
                bw.newLine();

            }
            bw.flush();
            bw.close();

            System.out.println("Success!");
        } catch (IOException e) {
            System.out.println("Couldn't create File!");
        }
    }

}