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Servlet Parameters null

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posted 10 years ago

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Hello, I have a servlet that is supposed to get the parameters from a JSP page form, set the parameters to a bean, and then save the bean to the session. I then have another JSP page that retrieves the session and displays the parameters in a table. My problem is all of my parameters are showing up null. I can't seem to figure out what is wrong. Here is my code: PageA JSP

<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <title>JSP Page</title>
    </head>
    <body>
        <h1>Add Item to Catalog</h1>
        <form action= "Confirmation.jsp" method ="post">
            <table border="0>"
            
            <tr>
              <td align="right">Movie ID:
               <input type="text" name="ID" size ="20"</td>
            </tr>
            <tr>
              <td align="right"> Movie Title
               <input type="text" name="Title" size="20"</td>
            </tr>
            <tr>
              <td align="right">Movie Genre: 
                <input type="text" name="Genre" size ="20"</td>
            </tr>
            <tr>
              <td align="right">Movie Price: 
                <input type="text" name="Price" size ="20"</td>
            </tr>
            <tr>
              <td align="right">Quantity in Stock: 
                <input type="text" name="Qty" size ="20"</td>
            </tr>
            
            <tr>
            <td align="right"> <input type="submit" value="Submit"</td>
            </tr>
            </table>
        </form>
    </body>
</html>

Controller Servlet:

public class ControllerServlet extends HttpServlet {

protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
       
       String userPath = request.getServletPath();
       
       //Declare the dispatcher for the View
       RequestDispatcher view= null;
       
        // get the session 
       HttpSession session = request.getSession();
               
       response.setContentType("text/html");
        PrintWriter out = response.getWriter();
       
       // if pageU  is requested
        if (userPath.equals("/secureUser/pageU")) {

//send the information to the catalog page
          view=request.getRequestDispatcher("/secureUser/pageU.jsp");
           view.forward(request, response);
        }
        // if PageA page is requested
        if (userPath.equals("/secureAdmin/pageA")) {
            
        //send the information to the  pageA
          view=request.getRequestDispatcher("/secureAdmin/pageA.jsp");
           view.forward(request, response);
        }
       
        
          
          
        
      
    }
    @Override
  protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        
        String userPath = request.getServletPath();
       
       //Declare the dispatcher for the View
       RequestDispatcher view= null;
       
        // get the session 
       HttpSession session = request.getSession();
       
        // if ItemsAdded page is requested
        if (userPath.equals("/secureAdmin/Confirmation")) {
    
        //Obtain parameters
        String id = request.getParameter("ID");
        String title = request.getParameter("Title");
        String genre = request.getParameter("Genre");
        String price = request.getParameter("Price");
        String qty = request.getParameter("Qty");
  
      //Create new instance of Movie Bean
      Movie movie = new Movie();
      
      movie.setID(id);
      movie.setTitle(title);
      movie.setGenre(genre);
      movie.setPrice(price);
      movie.setQty(qty);
      
      // store bean in the session object 
       session.setAttribute("movieBean", movie);

//send the information to the Confirmation.jsp
          view=request.getRequestDispatcher("/secureAdmin/Confirmation.jsp");
           view.forward(request, response);
        }
                    
                    }

}

Confirmation JSP

<%@page import = "Model.Movie"%>
    <jsp:useBean id="movieBean" scope="request"
                 class="Model.Movie"></jsp:useBean>
<%@page contentType="text/html" pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <title>Confirmation JSP Page</title>
    </head>
    <body>
        <h1>Your Movie has been added to the file!</h1>
         <h1>Confirmation Page</h1>
         <table border="1">
             <tr>
               <td>Movie ID: </td>
               <td><%=movieBean.getID() %></td>
           </tr>
           <tr>
               <td>Title: </td>
               <td><%=movieBean.getTitle() %></td>
           </tr>
           <tr>
               <td>Genre: </td>
               <td><%=movieBean.getGenre() %></td>
           </tr>
            <tr>
               <td>Price: </td>
               <td><%=movieBean.getPrice() %></td>
           </tr>
            <tr>
               <td>Quantity in Stock: </td>
               <td><%=movieBean.getQty() %></td>
           </tr>
       </table
    <li><a href="pageA">Add Another Movie</a</li> 
       
    </body>
</html>

I haven't included the Model.Movie Bean code but when I set the variables in my Bean they show up in my Confirmation page so I am assuming that the Bean code is legit.
Thanks for any and all help

Saif Asif

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posted 10 years ago

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Hello Brooke ,

<form action= "Confirmation.jsp" method ="post">

There is a slight issue in the flow of your application. You seem to be calling in the JSP directly. This is why the paremeters are wrong since your servlet is never called . The correct flow should be jsp --> servlet --> jsp . For this. You need to specify the name of your servlet here ( the ControllerServlet ) instead of the name of jsp. The name of the servlet must be the one as mapped in your web.xml deployment descriptor.
So change it to

Do post back for any further queries.

Muhammad Saif Asif Mirza
OCJA(5/6) OCJP(6) OCJWCD(6)

Brooke Maddox

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Okay so I changed my forms action to ControllerServlet. Now I am getting an HTTP Status 404 error, I have admin rights in my application so do I need to change my url pattern in my servlet even though my ControllerServlet is not under any admin folder?

Saif Asif

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Brooke Maddox wrote:Okay so I changed my forms action to ControllerServlet. Now I am getting an HTTP Status 404 error, I have admin rights in my application so do I need to change my url pattern in my servlet even though my ControllerServlet is not under any admin folder?

The servlet mapping shouldn't depend on any folder hierarchy , it should be mapped properly in the web.xml only, that is from where the container will find your serlvet based on the url pattern you hit. What is your mapping in the web.xml , post it here . Also I would like you to post what change have you made in your form action attribute and lastly the URL that was hit in the browser when you got the 404 error
( must be something like http://<servere_name>:<port>/<context_name>/some/more/paths/ControllerServlet

Muhammad Saif Asif Mirza
OCJA(5/6) OCJP(6) OCJWCD(6)

Brooke Maddox

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Here is my xml:

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.0" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">
    <context-param>
        <param-name>javax.faces.PROJECT_STAGE</param-name>
        <param-value>Development</param-value>
    </context-param>
    <servlet>
        <servlet-name>Faces Servlet</servlet-name>
        <servlet-class>javax.faces.webapp.FacesServlet</servlet-class>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>Faces Servlet</servlet-name>
        <url-pattern>/faces/*</url-pattern>
    </servlet-mapping>
    <session-config>
        <session-timeout>
            30
        </session-timeout>
    </session-config>
    <welcome-file-list>
        <welcome-file>View/index.jsp</welcome-file>
    </welcome-file-list>
    <security-constraint>
        <display-name>AdminConstraint </display-name>
        <web-resource-collection>
            <web-resource-name>Admin</web-resource-name>
            <description/>
            <url-pattern>/secureAdmin/*</url-pattern>
        </web-resource-collection>
        <auth-constraint>
            <description/>
            <role-name>AdminRole</role-name>
        </auth-constraint>
    </security-constraint>
    <security-constraint>
        <display-name>UserConstraint</display-name>
        <web-resource-collection>
            <web-resource-name>User</web-resource-name>
            <description/>
            <url-pattern>/secureUser/*</url-pattern>
        </web-resource-collection>
        <auth-constraint>
            <description/>
            <role-name>UserRole</role-name>
            <role-name>AdminRole</role-name>
        </auth-constraint>
    </security-constraint>
    <login-config>
        <auth-method>FORM</auth-method>
        <realm-name>file</realm-name>
        <form-login-config>
            <form-login-page>/View/LogIn.jsp</form-login-page>
            <form-error-page>/View/LogInError.jsp</form-error-page>
        </form-login-config>
    </login-config>
    <security-role>
        <description>Users added to this role have access to the secureUser directory of the server.</description>
        <role-name>UserRole</role-name>
    </security-role>
    <security-role>
        <description>Users added to this role have access to the secureAdmin directory of the server.
</description>
        <role-name>AdminRole</role-name>
    </security-role>
</web-app>

My JSP form

The url: http://localhost:8080/CMIS4407980_BNMProj2/secureAdmin/ControllerServlet

Bear Bibeault

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The URL of your form action should be server-relative; that is, start with the context path. See the JspFaq for more info.

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Saif Asif

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It seems that your URL is going in the context http://localhost:8080/CMIS4407980_BNMProj2/secureAdmin/ControllerServlet while my best guess ( since you also mentioned that the servlet is outside the admin realm ) is that it should be something like http://localhost:8080/CMIS4407980_BNMProj2/ControllerServlet .

As Bear said , go through the FAQ forum and try to search for how to do this.
Hint : Your issue is just related to paths .

Muhammad Saif Asif Mirza
OCJA(5/6) OCJP(6) OCJWCD(6)

Brooke Maddox

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Thanks Bear I found the topic on server-relative context paths. Now I seem to lose my connection to the localhost:8080 every time I run the application. Here is my new form

I added the following to my xml

Paul Clapham

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Brooke Maddox wrote:Now I seem to lose my connection to the localhost:8080 every time I run the application.

What makes you think that?

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Brooke Maddox

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Must have been a glitch with my server b/c now its not doing it. But my parameters are still null

Bear Bibeault

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Post an updated SSCCE

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Brooke Maddox

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PageA JSP

<form action= "${pageContext.request.contextPath}/ControllerServlet" method ="post">
            <table border="0>"
            
            <tr>
              <td align="right">Movie ID:
               <input type="text" name="ID" size ="20"</td>
            </tr>
            <tr>
              <td align="right"> Movie Title
               <input type="text" name="Title" size="20"</td>
            </tr>
            <tr>
              <td align="right">Movie Genre: 
                <input type="text" name="Genre" size ="20"</td>
            </tr>
            <tr>
              <td align="right">Movie Price: 
                <input type="text" name="Price" size ="20"</td>
            </tr>
            <tr>
              <td align="right">Quantity in Stock: 
                <input type="text" name="Qty" size ="20"</td>
            </tr>
            
            <tr>
            <td align="right"> <input type="submit" value="Submit"</td>
            </tr>
            </table>

ControllerServlet

protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        
        
       
       //Declare the dispatcher for the View
       RequestDispatcher view= null;
       
        // get the session 
       HttpSession session = request.getSession();
 
        //Obtain parameters
        int id = Integer.parseInt(request.getParameter("ID"));
        String title = request.getParameter("Title");
        String genre = request.getParameter("Genre");
        double price = Double.parseDouble(request.getParameter("Price"));
        int qty = Integer.parseInt(request.getParameter("Qty"));
  
      //Create new instance of Movie Bean
      Movie movie = new Movie();
      
      movie.setID(id);
      movie.setTitle(title);
      movie.setGenre(genre);
      movie.setPrice(price);
      movie.setQty(qty);
      
      // store bean in the session object 
       session.setAttribute("movieBean", movie); 
       
        
        //send the information to the Confirmation.jsp
          view=request.getRequestDispatcher("secureAdmin/Confirmation.jsp");
           view.forward(request, response);

Bear Bibeault

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And you have determined that the params are null, how...?

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Brooke Maddox

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I have a Confirmation JSP page that should post the parameters but they are all null. Here is the code for this page:

Bear Bibeault

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That's no proof that the params are null. There are many places along the pipe where things can go awry. In fact, the problem is not in the servlet.

And, why use the session rather than request scope? (Hint, hint)

(And, scriptlets in the JSP? Really?)

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