question archive Revise the survey sample servlet Survey
Revise the survey sample servlet Survey
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Revise the survey sample servlet Survey.java to record the number of votes so far in the data file and then display that count every time a vote is submitted or a survey result is requested. Also, change the output table so that its data is a percentage of the total votes for the particular gender category.
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<%--
Document : index - for the solution to Exercise 11.4
Created on : May 24, 2008, 8:37:33 PM
Author : bob
--%>
<%@page contentType="text/html" pageEncoding="UTF-8"%>
content="text/html; charset=UTF-8">
/* e114 - Servlet for Exercise 11.4 */
import java.io.*;
import java.net.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class Survey extends HttpServlet {
protected void processRequest(HttpServletRequest request,
HttpServletResponse response)
throws ServletException, IOException {
int votes[] = null;
int index;
int sumFemales, sumMales;
int vote;
File survdat = new File("survdat.ser");
String gender;
String products[] = {" TV", "Digital Camera", "MP3 player",
"DVD player/recorder", "Camcorder", "PDA", Other"};
// Set the content type for the response output and get a
// writer
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
// Create the initial part of the response document
out.println("");
out.println("");
out.println("");
out.println("");
out.println("");
// Synchronize a block for the votes file access
synchronized (this) {
// If the file already exists, read in its data
try {
if (survdat.exists()) {
ObjectInputStream indat = new
ObjectInputStream(
new FileInputStream(survdat));
votes = (int[]) indat.readObject();
indat.close();
}
// If the file does not exist (this is the first
// vote), create the votes array
else {
votes = new int[15];
votes[14] = 0;
}
} catch (Exception e) {
e.printStackTrace();
}
// Get the gender of the survey respondee
gender = request.getParameter("gender");
// Increment the visits counter
votes[14]++;
// Add the consumer electronics vote of the response to
// the votes array
vote = Integer.parseInt(request.getParameter("vote"));
if (gender.equals("male")) {
vote += votes.length / 2;
}
votes[vote]++;
//Write updated votes array to disk
ObjectOutputStream outdat = new ObjectOutputStream(
new FileOutputStream(survdat));
outdat.writeObject(votes);
outdat.flush();
outdat.close();
} //** end of the synchronized block
// Create the initial response information
out.println(
"
Thank you for participating in the");
out.println(" Consumer Electronics Survey
");
out.println("You are visitor number " + votes[14] +
"
");
out.println("
Current Survey Results:
");
// Create the total votes return information for female
// respondents
out.println("
For Female Respondents
");
// First, sum the votes for females and males
sumFemales = 0;
sumMales = 0;
for (index = 0; index < votes.length / 2; index++) {
sumFemales += votes[index];
sumMales += votes[index + votes.length / 2];
}
for (index = 0; index < votes.length / 2; index++) {
out.print(products[index]);
out.print(": ");
if (sumFemales > 0) {
out.print((100 * votes[index]) / sumFemales);
out.println("%");
}
else
out.println(0);
out.println("
");
}
// Create the total votes return information for male
// respondents
out.println("
For Male Respondents
"); for (index = votes.length / 2; index < votes.length; index++) { out.print(products[index - votes.length / 2]); out.print(": "); if (sumMales > 0) {out.print((100 * votes[index]) / sumMales); out.println("%"); } else out.println(0);out.println(" ");}out.close();}protected void doPost(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException { processRequest(request, response); }}
