httpjmsclientservlet.java

实现了Jms的服务器源码,支持多种适配器,DB,FTP,支持多种数据库

/**
 * Redistribution and use of this software and associated documentation
 * ("Software"), with or without modification, are permitted provided
 * that the following conditions are met:
 *
 * 1. Redistributions of source code must retain copyright
 *    statements and notices.  Redistributions must also contain a
 *    copy of this document.
 *
 * 2. Redistributions in binary form must reproduce the
 *    above copyright notice, this list of conditions and the
 *    following disclaimer in the documentation and/or other
 *    materials provided with the distribution.
 *
 * 3. The name "Exolab" must not be used to endorse or promote
 *    products derived from this Software without prior written
 *    permission of Exoffice Technologies.  For written permission,
 *    please contact [e-mail].
 *
 * 4. Products derived from this Software may not be called "Exolab"
 *    nor may "Exolab" appear in their names without prior written
 *    permission of Exoffice Technologies. Exolab is a registered
 *    trademark of Exoffice Technologies.
 *
 * 5. Due credit should be given to the Exolab Project
 *    (http://www.exolab.org/).
 *
 * THIS SOFTWARE IS PROVIDED BY EXOFFICE TECHNOLOGIES AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT
 * NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
 * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
 * EXOFFICE TECHNOLOGIES OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 *
 * Copyright 2001-2002 (C) Exoffice Technologies Inc. All Rights Reserved.
 *
 * $Id: HttpJmsClientServlet.java,v 1.7 2003/08/30 08:00:53 tanderson Exp $
 *
 * Date				Author  Changes
 * Fri 21 Sep 2001	mourikis    Created
 *
 */

package org.exolab.jms.client.http.servlet;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Vector;

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

import org.exolab.core.ipc.Client;


/**
 * This servlet forwards messages from the OpenJMS server to clients
 *
 * @version     $Revision: 1.7 $ $Date: 2003/08/30 08:00:53 $
 * @author      <a href="mailto:[e-mail]">Jim Mourikis</a>
 * @author      <a href="mailto:[e-mail]">Tim Anderson</a>
 */
public class HttpJmsClientServlet extends HttpServlet {

    /**
     * The list of active client connections, keyed on host and port.
     */
    private HashMap _connections = new HashMap();

    /**
     * The content type of the data.
     */
    private static final String CONTENT_TYPE = "text/html";

    /**
     * Called by the servlet container to indicate to a servlet that the
     * servlet is being placed into service.
     */
    public void init() {
        log("OpenJMS client servlet ready");
    }

    /**
     * Handle HTTP POST requests
     *
     * @param request contains the request the client has made of the servlet
     * @param response contains the response the servlet sends to the client
     * @throws IOException if an I/O error is encountered
     */
    public void doPost(HttpServletRequest request,
                       HttpServletResponse response) throws IOException {

        ObjectInputStream input = new ObjectInputStream(
            new BufferedInputStream(request.getInputStream()));

        ObjectOutputStream output = new ObjectOutputStream(
            new BufferedOutputStream(response.getOutputStream()));
        response.setContentType(CONTENT_TYPE);

        String host = request.getHeader("jms-host");
        int port = request.getIntHeader("jms-port");

        try {
            Object object = input.readObject();
            if (object instanceof Vector) {
                Vector message = (Vector) object;
                Client connection = getConnection(host, port);
                synchronized (connection) {
                    connection.send(message);
                    String type = request.getHeader("jms-response");
                    if (type != null && type.equals("yes")) {
                        message = (Vector) connection.receive();
                        output.writeObject(message);
                    }
                }

                response.setStatus(HttpServletResponse.SC_OK);
            } else if (object instanceof String &&
                       "close".equals(object)) {
                removeConnection(host, port);                
            } else {
                log("Received invalid request");
                response.setStatus(
                    HttpServletResponse.SC_UNSUPPORTED_MEDIA_TYPE);
                output.writeObject("Object is NULL, or UNEXPECTED type");
            }
        } catch (Exception exception) {
            log("Failed to process request", exception);
            removeConnection(host, port);
            response.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
            output.writeObject(exception.getMessage());
        } finally {
            output.flush();
        }
    }

    /**
     * Clean up client connections
     */
    public synchronized void destroy() {
        Iterator iterator = _connections.values().iterator();
        while (iterator.hasNext()) {
            Client client = (Client) iterator.next();
            try {
                client.close();
            } catch (IOException ignore) {
            }
        }
    }

    /**
     * Returns a cached TCP connection for the specified host name and
     * port number, creating one if none exists.
     *
     * @param host the host name of the client
     * @param port the TCP port number
     * @throws IOException if a connection cannot be establised
     */
    private synchronized Client getConnection(String host, int port)
        throws IOException {
        String key = host + ":" + port;
        Client client = (Client) _connections.get(key);

        if (client == null) {
            try {
                client = new Client(host, port);
            } catch (IOException exception) {
                throw new IOException("Failed to connect to host=" + host
                                      + ", port=" + port + ": "
                                      + exception.getMessage());
            }
            _connections.put(key, client);
        }
        return client;
    }

    /**
     * Remove a cached TCP connection.
     *
     * @param host the host name of the client
     * @param port the TCP port number
     */
    private synchronized void removeConnection(String host, int port) {
        String key = host + ":" + port;
        Client client = (Client) _connections.remove(key);
        if (client != null) {
            try {
                client.close();
            } catch (IOException ignore) {
                // may already be closed.
            }
        }
    }

} //-- HttpJmsClientServlet