?? survey.java
字號(hào):
// Survey.java
// This servlet processes the consumer electronics survey
// form, updating the file that stores the survey data
// and producing the current total votes in the survey.
// The survey data file, survdat.dat, is stored on the Web server.
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
public class Survey extends HttpServlet {
public void doPost(HttpServletRequest request,
HttpServletResponse response)
throws ServletException, IOException {
int votes[] = null;
int index;
int vote;
File survdat = new File("survdat.dat");
String gender;
String products[] = {"Conventional TV", "HDTV", "VCR",
"CD Player",
"Mini CD player/recorder",
"DVD player", "Other"};
// Set the content type for the response output and get a writer
response.setContentType( "text/html" );
PrintWriter servletOut = response.getWriter();
// Produce the head of the output document
servletOut.println("<html><head>");
servletOut.println(
"<title> Return message </title></head><body>");
// 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[14];
}
catch (Exception e) {e.printStackTrace();}
// Get the gender of the survey respondee
gender = request.getParameter("gender");
// Add the consumer electronics vote of the response to the
// votes array
vote = Integer.parseInt(request.getParameter("vote"));
if (gender.equals("male")) vote += 7;
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
servletOut.println(
"<h3>Thank you for participating in the");
servletOut.println(" Consumer Electronics Survey</h3>");
servletOut.println("<h4>Current Survey Results:</h4>");
// Create the total votes return information for female respondents
servletOut.println("<h5>For Female Respondents </h5>");
for (index = 0; index < 7; index++) {
servletOut.print(products[index]);
servletOut.print(": ");
servletOut.println(votes[index]);
servletOut.println("<br />");
}
// Create the total votes return information for male respondents
servletOut.println("<h5>For Male Respondents </h5>");
for (index = 7; index < 14; index++) {
servletOut.print(products[index - 7]);
servletOut.print(": ");
servletOut.println(votes[index]);
servletOut.println("<br />");
}
servletOut.close();
}
}
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