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public class ESAServlet extends HttpServlet {

    private static final long serialVersionUID = 1L;

    protected ServletContext context;

    protected ESASearcher esa;

    protected DecimalFormat df = (DecimalFormat) NumberFormat.getInstance(Locale.US);


    static Connection connection;
    static Statement stmtQuery;

    static String strTitles = "SELECT id,title FROM article WHERE id IN ";

    public static void initDB() throws ClassNotFoundException, SQLException, IOException {
        // Load the JDBC driver
        String driverName = "com.mysql.jdbc.Driver"; // MySQL Connector
        Class.forName(driverName);

        // read DB config
        InputStream is = ESASearcher.class.getResourceAsStream("/config/db.conf");
        BufferedReader br = new BufferedReader(new InputStreamReader(is));
        String serverName = br.readLine();
        String mydatabase = br.readLine();
        String username = br.readLine();
        String password = br.readLine();
        br.close();

        // Create a connection to the database
        String url = "jdbc:mysql://" + serverName + "/" + mydatabase; // a JDBC url
        connection = DriverManager.getConnection(url, username, password);

        stmtQuery = connection.createStatement();
        stmtQuery.setFetchSize(100);
    }


    public void init(ServletConfig config) throws ServletException {
        super.init(config);
        context = config.getServletContext();
        try {
            esa = new ESASearcher();
            initDB();
        } catch (Exception e) {
            e.printStackTrace();
            throw new ServletException();
        }
    }

    public void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {

        doGet(request, response);

    }

    public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {

        try {

            response.setHeader("Cache-Control", "no-cache");
            response.setCharacterEncoding("UTF-8");

            String task = request.getParameter("task");

            //redirect to home page if there is no task
            if (task == null) {
                response.setContentType("text/html");
                response.getWriter().append("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.0 Transitional//EN\"><html><head><meta http-equiv=\"REFRESH\" content=\"0;url=" + context.getInitParameter("server_path") + "></head><body></body></html>");
                return;
            }

            //process compare request
            if (task.equals("esa")) {
                String term1 = request.getParameter("term1");
                String term2 = request.getParameter("term2");

                if (term1 == null || term2 == null) {
                    response.setContentType("text/html");
                    response.getWriter().append("-1");
                    return;
                } else {
                    final double sim = esa.getRelatedness(term1, term2);
                    response.setContentType("text/html");
                    response.getWriter().append(df.format(sim));
                    return;
                }

            }

            //process compare request
            if (task.equals("vector")) {
                final String source = request.getParameter("source");
                final String strLimit = request.getParameter("limit");

                int limit;

                if (strLimit == null) {
                    limit = 10;
                } else {
                    limit = Integer.valueOf(strLimit);
                }

                if (source == null) {
                    response.setContentType("text/html");
                    response.getWriter().append("null");
                    return;
                } else {
                    response.setContentType("text/html");

                    final IConceptVector cv = esa.getConceptVector(source);

                    if (cv == null) {
                        response.getWriter().append("null");
                    } else {
                        final IConceptVector ncv = esa.getNormalVector(cv, limit);
                        final IConceptIterator it = ncv.orderedIterator();

                        HashMap<Integer, Double> vals = new HashMap<Integer, Double>(10);
                        HashMap<Integer, String> titles = new HashMap<Integer, String>(10);

                        String inPart = "(";

                        int count = 0;
                        while (it.next() && count < limit) {
                            inPart += it.getId() + ",";
                            vals.put(it.getId(), it.getValue());
                            count++;
                        }

                        inPart = inPart.substring(0, inPart.length() - 1) + ")";

                        ResultSet r = stmtQuery.executeQuery(strTitles + inPart);
                        while (r.next()) {
                            titles.put(r.getInt(1), new String(r.getBytes(2), "UTF-8"));
                        }


                        it.reset();
                        count = 0;
                        while (it.next() && count < limit) {
                            int id = it.getId();
                            response.getWriter().append(id + "\t" + titles.get(id) + "\t" + df.format(vals.get(id)) + "\n");
                            count++;
                        }
                    }
                    return;
                }

            }


        } catch (Exception error) {
            response.reset();
            response.setContentType("application/xml");
            response.setHeader("Cache-Control", "no-cache");
            response.setCharacterEncoding("UTF8");

            response.getWriter().append("error");
        }
    }

}