Passing web.xml info to servlets

Greenhorn

Posts: 3

posted 22 years ago

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Help i'm stuck....trying to send information from web.xml to MyBasket.java servlet to SimpleShoppingBasket servlet. The information from the web.xml file is passed successfully to the first servlet, but all information (apart from quantities) are listed as 0 or null when trying to send to the second servlet.
I'm new to servlets so dont really have a clue what i'm doing!!! Could anyone help? I have included my code if anyone fancies giving me a few tips!!
FIRST SERVLET:

package Basket;
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.util.*;
public class MyBasket extends HttpServlet{
  public void init() throws ServletException{
    System.out.println( "Servlet initialised" );
  }
  private String startWebPage(){
    return "<HTML><HEAD><TITLE>My Basket</TITLE></HEAD><BODY>" +
           "<FORM action='../servlet/SimpleShoppingBasket' method='POST'>" +
           "<TABLE ALIGN='center' BORDER='1' WIDTH='50%' CELLSPACING='3' CELLPADDING='3'>" +
           "<TR><TH ALIGN='center' VALIGN='top'>Item</TH>" +
           "<TH ALIGN='center' VALIGN='top'>Unit Price (�)</TH>" +
           "<TH ALIGN='center' VALIGN='top'>Quantity</TH></TR>";
  }
  private String endWebPage(){
  return  "<TR><TD ALIGN='center' VALIGN='top' COLSPAN=3>" +
          "<INPUT TYPE='submit' VALUE='Continue'>" +
          "<INPUT TYPE='reset' VALUE='Clear'></TD></TR></TABLE></FORM></BODY></HTML>";
  }
public void doGet(HttpServletRequest request, HttpServletResponse response)
  throws IOException, ServletException{
  response.setContentType("text/html");
  PrintWriter out = response.getWriter();
  Enumeration enum = this.getInitParameterNames();
  out.println(this.startWebPage());
   while (enum.hasMoreElements()){
      String name = ( String )enum.nextElement();
      String value = this.getInitParameter( name );
      out.println("<TR><TD>" + name + "</TD><TD>" + value + "</TD>");
      out.println("<TD ALIGN='left' VALIGN='top'>" +
                  "<SELECT NAME='choices'>" +
                  "<OPTION>0" +
                  "<OPTION>1" +
                  "<OPTION>2" +
                  "<OPTION>3" +
                  "<OPTION>4" +
                  "</SELECT></TD></TR>");
    }
      out.println(endWebPage());
  }
}

WEB.XML FILE:

<!DOCTYPE web-app 
    PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.2//EN" 
    "http://java.sun.com/j2ee/dtds/web-app_2_2.dtd">
<web-app>
    <display-name>Get method example</display-name>
    <description>
This is a simple web application with a source code organization
based on the recommendations of the Application Developer's Guide.
    </description>
    <servlet>
        <servlet-name>getExample</servlet-name>
        <servlet-class>Attributes</servlet-class>
    </servlet>
    <servlet>
        <servlet-name>getInitializationParameters</servlet-name>
        <servlet-class>Init_param</servlet-class>
        <init-param>
            <param-name>version </param-name>
            <param-value> best</param-value>
        </init-param>
    </servlet>
    
    
    <servlet>
        <servlet-name>getBasketParameters</servlet-name>
        <servlet-class>Basket.MyBasket</servlet-class>
    <init-param>
    <param-name>Socks</param-name>
        <param-value>1</param-value>
        </init-param>
        <init-param>
       <param-name>Hat</param-name>
       <param-value>10</param-value>
        </init-param>
        <init-param>
        <param-name>Shoes</param-name>
        <param-value>40</param-value>
        </init-param>
    <init-param>
        <param-name>Glasses</param-name>
        <param-value>20</param-value>
        </init-param>
    <init-param>
       <param-name>Ring</param-name>
       <param-value>15</param-value>
        </init-param>
    </servlet>
    
    <servlet-mapping>
        <servlet-name>getExample</servlet-name>
        <url-pattern>/send</url-pattern>
    </servlet-mapping>
    
     <servlet-mapping>
        <servlet-name>getInitializationParameters</servlet-name>
        <url-pattern>/init</url-pattern>
    </servlet-mapping>
    
    <servlet-mapping>
    <servlet-name>getBasketParameters</servlet-name>
    <url-pattern>/shop</url-pattern>
    </servlet-mapping>
    
  </web-app>

SECOND SERVLET:

import java.io.*;
import java.util.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class SimpleShoppingBasket extends HttpServlet {
public void init() throws ServletException{
  System.out.println("Servlet Initialised");
  }
public void doPost(HttpServletRequest request, HttpServletResponse response)
  throws IOException, ServletException{

response.setContentType("text/html");
  PrintWriter out = response.getWriter();
  out.println("<HTML><BODY>");
  Enumeration aEnum = request.getParameterNames();
  int[] unitprices = null;
  int[] quantities = null;
  String[] products = null;
 while (aEnum.hasMoreElements()){
      String parameterName = ( String )aEnum.nextElement();
      System.out.println(parameterName);
      String[] values = request.getParameterValues(parameterName);
      if (unitprices == null) unitprices = new int[values.length];
      if (quantities == null) quantities = new int[values.length];
      if (products == null) products= new String[values.length];
      for(int i = 0; i < values.length; i++){
        if(parameterName.equals("price")){
          unitprices[i] = Integer.parseInt(values[i]);
         }
         else if(parameterName.equals("choices")){
          quantities[i] = Integer.parseInt(values[i]);
         }
         else if(parameterName.equals("items")){
          products[i] = values[i];
         }
         System.out.println(products[i] + " " + quantities[i] + " " + unitprices[i]);
      }
  }
  out.println("<TABLE ALIGN='center' BORDER='1' WIDTH='50%' CELLSPACING='3' CELLPADDING='3'><TR>" + "\n" +
              "<TR><TH>Item</TH><TH>Unit Price (�)</TH><TH>Quantity</TH><TH>Total</TH>");
  int total = 0;
  for(int i =0; i < products.length; i ++){
    total += quantities[i] * unitprices[i];
    out.println("<TR><TD>" + products[i] + "</TD><TD>" + unitprices[i] + "</TD><TD>" + 
quantities[i] + "</TD><TD ALIGN='right'>" + unitprices[i] * quantities[i] + "</TD></TR>");
  }
  out.println("<TR><TD ALIGN='left' VALIGN='top' COLSPAN=3>Grand Total</TD>");
  out.println("<TD ALIGN='right' VALIGN='top'>" + total + "</TD></TR>");
  out.println("</TABLE></BODY></HTML>");
}
}

[ January 15, 2002: Message edited by: Mike Curwen ]

Mike Curwen

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Posts: 3695

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posted 22 years ago

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Hi Caroline, welcome to the Ranch.

I've edited your post to include the UBB [ code ] tags.

Here's what I came up with. First, I've modified your web.xml a little bit:

Then, your first servlet is modified thus: Then, your second servlet...
As for what you are doing in the second servlet, you are attempting to retrive from the request, the values that you had placed into your table in the first servlet. But these values are not IN the request. They are only 'plain HTML' as output by that first servlet.

If you want to retrieve the name and quantity and price, these need to be made form fields as well, so that when you POST to the second servlet, they are placed in the request as well.

I could also get into the whole discussion about architecture, databases and how init-parameters aren't the best way to be doing what you are doing... but thought I'd just answer your question.

You need to make everything you want to retrieve from the request (in your second servlet) a parameter on the FORM in the first page.
[ January 15, 2002: Message edited by: Mike Curwen ]

Caroline Harris

Greenhorn

Posts: 3

posted 22 years ago

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Thanks for the suggestions.....tried the 'hidden' types, but still didnt work!!
I must be doing something wrong! Do u have any other suggestions or links that might help me understand more?
Thanks
Caroline

Caroline Harris

Greenhorn

Posts: 3

posted 22 years ago

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Hi Mike...i read through my code again and i'd made a boo boo!! Typo!
Your suggestion did work. Thank you very much!
Caroline

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