package examples.servlets;
/*
 * @(#)SurveyServlet.java
 *
 * Copyright (c) 1995-1997 Sun Microsystems, Inc. All Rights Reserved.
 *
 * This software is the confidential and proprietary information of Sun
 * Microsystems, Inc. ("Confidential Information").  You shall not
 * disclose such Confidential Information and shall use it only in
 * accordance with the terms of the license agreement you entered into
 * with Sun.
 * 
 * SUN MAKES NO REPRESENTATIONS OR WARRANTIES ABOUT THE SUITABILITY OF THE
 * SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
 * PURPOSE, OR NON-INFRINGEMENT. SUN SHALL NOT BE LIABLE FOR ANY DAMAGES
 * SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR DISTRIBUTING
 * THIS SOFTWARE OR ITS DERIVATIVES.
 */

import java.io.*;
import java.util.*;

import javax.servlet.*;
import javax.servlet.http.*;
/**
 * This example servlet takes input from a form and writes it out to a simple
 * text file. After the results are written to the file, the servlet returns a
 * "thank you" to the user. This example has been modified from the SurveyServlet 
 * that is distributed with the JSDK2.0  - see note below. 
 * 
 * <p><b>Note:</b> This servlet has been modified from the SurveyServlet that is
 * distributed with the JSDK2.0 so that it does not implement the
 * SingleThreadModel. WebLogic does not support the SingleThreadModel. This model
 * is of limited value, and the original JavaSoft example illustrated here is
 * bogus with respect to ensuring that output to the text file is guarded against
 * simultaneous access from multiple servlet threads. Although the 
 * SingleThreadModel does prevent a sevlets engine from invoking a servlet 
 * instance with multiple threads simultaneously, the spec describes that the server may 
 * initialize any number of servlet instances. In this example these servlet 
 * instances would all access and write to the same file - possibly 
 * simultaneously, regardless of the SingleTreadModel interface. See the note in the 
 * WebLogic servlet developer's guide for more details. 
 * 
 * @author Adapted from the JSDK2.0 by BEA Systems, Inc. 
 */

public class SurveyServlet extends HttpServlet 
{
  String resultsDir;
  
  public void init(ServletConfig config)
       throws ServletException
  {
    super.init(config);
    resultsDir = getInitParameter("resultsDir");
    if (resultsDir == null) {
      Enumeration initParams = getInitParameterNames();
      System.err.println("The init parameters were: ");
      while (initParams.hasMoreElements()) {
        System.err.println(initParams.nextElement());
      }
      System.err.println("Should have seen one parameter name");
      throw new UnavailableException (this,
                                      "Not given a directory to write survey results!");
    }
  }
  
  /**
   * Write survey results to output file in response to the POSTed
   * form.  Write a "thank you" to the client.     
   */
  public void doPost(HttpServletRequest req, HttpServletResponse res)
       throws ServletException, IOException
  {
    // first, set the "content type" header of the response
    res.setContentType("text/html");
    
    //Get the response's PrintWriter to return text to the client.
    PrintWriter toClient = res.getWriter();
    
    try {
      //Open the file for writing the survey results.
      String surveyName = req.getParameterValues("survey")[0];
      FileWriter resultsFile = new FileWriter(resultsDir
                                              + System.getProperty("file.separator")
                                              + surveyName + ".txt", true);
      PrintWriter toFile = new PrintWriter(resultsFile);
      
      // Get client's form data & append it to the file
      toFile.println("<BEGIN>");
      Enumeration values = req.getParameterNames();
      while(values.hasMoreElements()) {
        String name = (String)values.nextElement();
        String value = req.getParameterValues(name)[0];
        // Don't write the submit parameter
        if(name.compareTo("submit") != 0) {
          toFile.println(name + ": " + value);
        }
      }
      toFile.println("<END>");
      
      //Close the file.
      resultsFile.close();
      
      // Respond to client with a thank you
      toClient.println("<html>");
      toClient.println("<title>Thank you!</title>");
      toClient.println("<body bgcolor=#ffffff><font face=\"Helvetica\">" +
                       "Thank you for participating</font></body>");
      toClient.println("</html>");
      
    } catch(IOException e) {
      e.printStackTrace();
      toClient.println("A problem occured while recording your answers. " +
                       "Please try again.");
    }
    
  }
}