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ActiveMQ example source code file (PortfolioPublishServlet.java)

This example ActiveMQ source code file (PortfolioPublishServlet.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - ActiveMQ tags/keywords

double, double, hashtable, http, io, ioexception, jmsexception, last_prices, max_delta_percent, max_delta_percent, messageservletsupport, printwriter, request, response, servlet, servletexception, servletexception, string, string, util

The ActiveMQ PortfolioPublishServlet.java source code

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.activemq.web;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.Hashtable;
import java.util.Map;

import javax.jms.Destination;
import javax.jms.JMSException;
import javax.jms.Message;
import javax.jms.Session;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * A servlet which will publish dummy market data prices
 * 
 * 
 */
public class PortfolioPublishServlet extends MessageServletSupport {

    private static final int MAX_DELTA_PERCENT = 1;
    private static final Map<String, Double> LAST_PRICES = new Hashtable();

    public void init() throws ServletException {
        super.init();
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        PrintWriter out = response.getWriter();
        String[] stocks = request.getParameterValues("stocks");
        if (stocks == null || stocks.length == 0) {
            out.println("<html>No stocks query parameter specified. Cannot publish market data");
        } else {
            Integer total = (Integer)request.getSession(true).getAttribute("total");
            if (total == null) {
                total = Integer.valueOf(0);
            }

            int count = getNumberOfMessages(request);
            total = Integer.valueOf(total.intValue() + count);
            request.getSession().setAttribute("total", total);

            try {
                WebClient client = WebClient.getWebClient(request);
                for (int i = 0; i < count; i++) {
                    sendMessage(client, stocks);
                }
                out.print("<html>");
                out.println("<body>Published " + count + " of " + total + " price messages.  Refresh = " + refreshRate + "s");
                out.println("</body>");

            } catch (JMSException e) {
                out.println("<html>Failed sending price messages due to " + e + "");
                log("Failed to send message: " + e, e);
            }
        }
    }

    protected void sendMessage(WebClient client, String[] stocks) throws JMSException {
        Session session = client.getSession();

        int idx = 0;
        while (true) {
            idx = (int)Math.round(stocks.length * Math.random());
            if (idx < stocks.length) {
                break;
            }
        }
        String stock = stocks[idx];
        Destination destination = session.createTopic("STOCKS." + stock);
        String stockText = createStockText(stock);
        log("Sending: " + stockText + " on destination: " + destination);
        Message message = session.createTextMessage(stockText);
        client.send(destination, message);
    }

    protected String createStockText(String stock) {
        Double value = LAST_PRICES.get(stock);
        if (value == null) {
            value = new Double(Math.random() * 100);
        }

        // lets mutate the value by some percentage
        double oldPrice = value.doubleValue();
        value = new Double(mutatePrice(oldPrice));
        LAST_PRICES.put(stock, value);
        double price = value.doubleValue();

        double offer = price * 1.001;

        String movement = (price > oldPrice) ? "up" : "down";
        return "<price stock='" + stock + "' bid='" + price + "' offer='" + offer + "' movement='" + movement + "'/>";
    }

    protected double mutatePrice(double price) {
        double percentChange = (2 * Math.random() * MAX_DELTA_PERCENT) - MAX_DELTA_PERCENT;

        return price * (100 + percentChange) / 100;
    }

    protected int getNumberOfMessages(HttpServletRequest request) {
        String name = request.getParameter("count");
        if (name != null) {
            return Integer.parseInt(name);
        }
        return 1;
    }
}

Other ActiveMQ examples (source code examples)

Here is a short list of links related to this ActiveMQ PortfolioPublishServlet.java source code file:
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