// Fig. 19.7: HTTPPostServlet.java
// A simple survey servlet
import javax.servlet.*;
import javax.servlet.http.*;
import java.text.*;
import java.io.*;
import java.util.*;
public class HTTPPostServlet extends HttpServlet {
private String animalNames[] =
{ "dog", "cat", "bird", "snake", "none" };
public void doPost( HttpServletRequest request,
HttpServletResponse response )
throws ServletException, IOException
{
int animals[] = null, total = 0;
File f = new File( "survey.txt" );
if ( f.exists() ) {
// Determine # of survey responses so far
try {
ObjectInputStream input = new ObjectInputStream(
new FileInputStream( f ) );
animals = (int []) input.readObject();
input.close(); // close stream
for ( int i = 0; i < animals.length; ++i )
total += animals[ i ];
}
catch( ClassNotFoundException cnfe ) {
cnfe.printStackTrace();
}
}
else
animals = new int[ 5 ];
// read current survey response
String value =
request.getParameter( "animal" );
++total; // update total of all responses
// determine which was selected and update its total
for ( int i = 0; i < animalNames.length; ++i )
if ( value.equals( animalNames[ i ] ) )
++animals[ i ];
// write updated totals out to disk
ObjectOutputStream output = new ObjectOutputStream(
new FileOutputStream( f ) );
output.writeObject( animals );
output.flush();
output.close();
// Calculate percentages
double percentages[] = new double[ animals.length ];
for ( int i = 0; i < percentages.length; ++i )
percentages[ i ] = 100.0 * animals[ i ] / total;
// send a thank you message to client
response.setContentType( "text/html" ); // content type
PrintWriter responseOutput = response.getWriter();
StringBuffer buf = new StringBuffer();
buf.append( "\n" );
buf.append( "Thank you!\n" );
buf.append( "Thank you for participating.\n" );
buf.append( "
Results:\n" );
DecimalFormat twoDigits = new DecimalFormat( "#0.00" );
for ( int i = 0; i < percentages.length; ++i ) {
buf.append( "
" );
buf.append( animalNames[ i ] );
buf.append( ": " );
buf.append( twoDigits.format( percentages[ i ] ) );
buf.append( "% responses: " );
buf.append( animals[ i ] );
buf.append( "\n" );
}
buf.append( "\n
Total responses: " );
buf.append( total );
buf.append( "\n" );
responseOutput.println( buf.toString() );
responseOutput.close();
}
}
/**************************************************************************
* (C) Copyright 1999 by Deitel & Associates, Inc. and Prentice Hall. *
* All Rights Reserved. *
* *
* DISCLAIMER: The authors and publisher of this book have used their *
* best efforts in preparing the book. These efforts include the *
* development, research, and testing of the theories and programs *
* to determine their effectiveness. The authors and publisher make *
* no warranty of any kind, expressed or implied, with regard to these *
* programs or to the documentation contained in these books. The authors *
* and publisher shall not be liable in any event for incidental or *
* consequential damages in connection with, or arising out of, the *
* furnishing, performance, or use of these programs. *
*************************************************************************/