fileexchangeservlet.java

来自「JAVA Servlet2.3外文书籍源码」· Java 代码 · 共 109 行

package firewall.server;

import firewall.common.*;

import javax.servlet.http.HttpServlet;

import java.io.*;

import javax.servlet.*;
import javax.servlet.http.*;

import java.io.IOException;
import java.io.PrintWriter;

/**
 * Title:        FileExchangeServlet
 * Description:  Servlet that handles the client requests and delegates
 *               processing to the appropriate handler
 * Copyright:    Copyright (c) 2001
 * Company:
 * @author Andrew Harbourne-Thomas
 * @version 1.0
 */
public class FileExchangeServlet extends HttpServlet {

  /** Reference to the RequestHandlerFactory singleton instance */
  private RequestHandlerFactory requestHandlerFactory = null;

  /**
   * Initialise the RequestHandlerFactory singleton
   *
   * @throws ServletException
   */
  public void init() throws ServletException {
    //this is the location of our files directory
    String directory = getServletContext().getRealPath("/") +
                        "WEB-INF" + File.separator + "files" + File.separator ;
    //ensure that the RequestHandler knows the correct directory
    //where the files are located
    RequestHandler.setStringFileBase(directory);
    requestHandlerFactory = RequestHandlerFactory.getInstance();
  }

  /**
   * Post method handles post requests from application, by activating the
   * appropriate handler and calling the handler.respond(..) method to
   * process the request
   *
   * @param request The HTTP request object
   * @param response The HTTP response object
   *
   * @throws IOException
   * @throws ServletException
   */
  public void doPost(HttpServletRequest request, HttpServletResponse response)
          throws ServletException, IOException {
    try {
      //read the request object
      BaseRequest baseObject = (BaseRequest) readSerializedObject(request);
      //get the appropriate handler
      RequestHandler handler =
        (RequestHandler) requestHandlerFactory
          .getHandler(baseObject.getRequestType());
      //pass in the request, response objects to the handler
      handler.setHttpObjects(request, response);
      //process the request
      handler.respond(baseObject);
    }
    catch (ClassNotFoundException cnfe) {
      cnfe.printStackTrace();
    }
    catch (IOException ioe) {
      ioe.printStackTrace();
    }
  }

  /**
   * Get method forwards request to the doPost method.
   *
   * @param request The HTTP request object
   * @param response The HTTP response object
   *
   * @throws IOException
   * @throws ServletException
   */
  public void doGet(HttpServletRequest request, HttpServletResponse response)
          throws ServletException, IOException {
    doPost(request, response);
  }

  /**
   * Method to extract an object sent by the client as part of its request to
   * the server
   *
   * @param httpServletRequest Request to extract object from
   *
   * @return Object read in from the clients request
   *
   * @throws ClassNotFoundException
   * @throws IOException
   */
  private Object readSerializedObject(HttpServletRequest httpServletRequest)
          throws IOException, ClassNotFoundException {
    ObjectInputStream ois =
      new ObjectInputStream(httpServletRequest.getInputStream());
    Object readObject = ois.readObject();
    return readObject;
  }
}