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RequestDispatcher not working in Servlet.

Greenhorn

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posted 1 year ago

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I am working with a servlet project in which the user inputs data in a form and if the terms and conditions are not met then the form is displayed.
However, the above functionality does not seem to work?
How do I fix it?

index.html

<!DOCTYPE html>
<html>
    <head>
        <title>Form</title>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <style>
            .container{
                width:40%;
                border:1px solid black;
                margin:auto;
                padding:20px;
                font-size:20px;
            }
            
            #my-form tr td input{
                font-size:20px;
            }
        </style>
    </head>
    <body>
        <div class="container">
            <h1>My Form</h1>
            <form id="my-form" action="RegisterServlet" method="post">
                <table>
                    <tr>
                        <td>
                            Name:
                        </td>
                        <td>
                            <input type="text" name="user_name" placeholder="Enter your name"/>
                        </td>
                    </tr>
                    <tr>
                        <td>
                            Password:
                        </td>
                        <td>
                            <input type="password" name="user_password" placeholder="Enter your password"/>
                        </td>
                    </tr>
                    <tr>
                        <td>
                            Email:
                        </td>
                        <td>
                            <input type="email" name="user_email" placeholder="Enter your email"/>
                        </td>
                    </tr>
                     <tr>
                        <td>
                            Gender:
                        </td>
                        <td>
                            <input type="radio" name="user_gender"/>Male    <input type="radio" name="user_gender" />Female
                        </td>
                    </tr>
                     <tr>
                        <td>
                            Course:
                        </td>
                        <td>
                            <select name="user_course">
                                <option value="Java">Java</option>
                                <option value="C++">C++</option>
                                <option value="C">C</option>
                                <option value="Python">Python</option>
                            </select>
                        </td>
                    </tr>
                    <tr style="text-align:center">
                        <td>
                             <input type="checkbox" value="checked" name="conditiontocheck"/>
                        </td>
                        <td>
                            Agree terms and conditions
                        </td>
                    </tr>
                    <tr style="text-align:center">
                        <td>
                             
                        </td>
                        <td>
                            <button type="submit">Register</button>
                             <button type="reset">Reset</button>
                        </td>
                    </tr>
                </table>
            </form>
        </div>
    </body>
</html>

RegisterServlet.java

/*
 * Click nbfs://nbhost/SystemFileSystem/Templates/Licenses/license-default.txt to change this license
 * Click nbfs://nbhost/SystemFileSystem/Templates/Classes/Class.java to edit this template
 */
package com.packages;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.*;
import javax.servlet.http.*;

/**
 *
 * @author soura
 */
public class RegisterServlet extends HttpServlet{
    @Override
    public void doPost(HttpServletRequest request,HttpServletResponse response)throws ServletException,IOException{
        response.setContentType("text/html");
        PrintWriter out=response.getWriter();
        out.println("<h1>Welcome to Register Servlet</h1>");
        String name=request.getParameter("user_name");
        String password=request.getParameter("user_password");
        String email=request.getParameter("user_mail");
        String gender=request.getParameter("user_gender");
        String course=request.getParameter("user_course");
        
         String condition=request.getParameter("conditiontocheck");
         
         if(condition!=null){
            if(condition.equals("checked")){
                out.println("<h2>Name:</h2>"+name);
                out.println("<h2>Password:</h2>"+password);
                out.println("<h2>Email:</h2>"+email);
                out.println("<h2>Gensder:</h2>"+gender);
                out.println("<h2>Course:</h2>"+course);      
            }else{
             out.println("The terms and conditions have not been applied."); 
            }
         }
         else{
            out.println("The terms and conditions have not been applied."); 
            RequestDispatcher rd=request.getRequestDispatcher("index.html");
            rd.include(request,response);
         }
    }   
}

web.xml

Ron McLeod

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Sourabh Chavan wrote:... the above functionality does not seem to work

You will need to provide some details.

What were you expecting, and what did you observe?

Paul Clapham

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Sourabh Chavan wrote:However, the above functionality does not seem to work?

What makes you think that it doesn't work? (Or are you still unsure whether it works or not?)

Java 8 (verified skill)
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Sourabh Chavan

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posted 1 year ago

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Ron McLeod wrote:

Sourabh Chavan wrote:... the above functionality does not seem to work

You will need to provide some details.

What were you expecting, and what did you observe?

I was expecting that when I run the app on netbeans and don't click on terms and conditions agree the browser displays the form with details with the text "the terms and consitions have not been agreed"

Sourabh Chavan

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Paul Clapham wrote:

Sourabh Chavan wrote:However, the above functionality does not seem to work?

What makes you think that it doesn't work? (Or are you still unsure whether it works or not?)

Ron McLeod

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Sourabh Chavan wrote:I was expecting that when I run the app on netbeans and don't click on terms and conditions agree the browser displays the form with details with the text "the terms and consitions have not been agreed"

And what was actually displayed?

Sourabh Chavan

Greenhorn

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Ron McLeod wrote:

Sourabh Chavan wrote:I was expecting that when I run the app on netbeans and don't click on terms and conditions agree the browser displays the form with details with the text "the terms and consitions have not been agreed"

And what was actually displayed?

However, the form is displayed without the details I entered.

Ron McLeod

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I guess that is because if your check for the conditions being accepted (condition!=null) returns false, then you send back the same static HTML content that you sent originally, which does not include any values.

Sourabh Chavan

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Ron McLeod wrote:I guess that is because if your check for the conditions being accepted (condition!=null) returns false, then you send back the same static HTML content that you sent originally, which does not include any values.
if(condition!=null){ ... } else{ out.println("The terms and conditions have not been applied."); RequestDispatcher rd=request.getRequestDispatcher("index.html"); rd.include(request,response); }

So, how to fix?
I am new to servlets

Ron McLeod

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I haven't worked with Servlets for a while, so I am probably not the best one to answer, but one solution would be to use JSPs (Java Server Pages) and java.lang.EL (Java Expression Language).

Ron McLeod

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Something else I noticed ... I'm assuming that since you are not specifying specific values for for the radio input elements, that you are seeing a value of on for gender, and are unable to distinguish between male/female.

To fix this, modify your existing code:
To include values for male and female:
Or even better, using labels:

Sourabh Chavan

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Ron McLeod wrote:Something else I noticed ... I'm assuming that since you are not specifying specific values for for the radio input elements, that you are seeing a value of on for gender, and are unable to distinguish between male/female.

To fix this, modify your existing code:<input type="radio" name="user_gender"/>Male <input type="radio" name="user_gender" />Female
To include values for male and female:<input type="radio" name="user_gender" value="M">Male <input type="radio" name="user_gender" value="F">Female
Or even better, using labels:<input type="radio" id="g_male" name="user_gender" value="M"> <label for="g_male">Male</label> <input type="radio" id="g_female" name="user_gender" value="F"> <label for="g_female">Female</label>

Can you help me about ,y form problem?

Ron McLeod

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Sourabh Chavan wrote:Can you help me about ,y form problem?

Sorry - all I can suggest is that if you want to use server-side rendering with dynamic content, then maybe take a look at JSPs. Hopefully others can make better recommendations.

Paul Clapham

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I wouldn't write that code like that either. And I don't know how to run it in Netbeans so you might be doing that wrong or expecting something different than what Netbeans does. But anyway I'd suggest that debugging the Java code would be helpful.

Ron McLeod

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Ron McLeod wrote:I haven't worked with Servlets for a while, so I am probably not the best one to answer, but one solution would be to use JSPs (Java Server Pages) and java.lang.EL (Java Expression Language).

I had some time today so I reworked your project to use JSP and EL. It's not perfect, but it should be good-enough provide an example of how to use JSPs. Reply-back here if you have any questions.

RegisterServlet.java

import java.io.IOException;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;

import javax.servlet.*;
import javax.servlet.http.*;

import com.packages.beans.RegisterData;

/**
 *
 * @author soura
 */
public class RegisterServlet extends HttpServlet {
    private static final String BEAN_ATTR = "bean";
    private static final String MESSAGE_ATTR = "message";
    private static final String BEEN_HERE_ATTR = "been-here";
    private static final String COURSES_ATTR = "courses";
    private static final String GENDERS_ATTR = "genders";
    private static final String WELCOME_MESSAGE = "Welcome to Register Servlet";
    private static final String NOT_AGREED_MESSAGE = "The terms and conditions have not been applied.";
    private static final String REGISTERED_MESSAGE = "Thank-you";

private static final List<String> COURSES = List.of("Java", "C++", "C", "Python");

// doing this to maintain insertion order
    private static final Map<String, String> GENDERS = new LinkedHashMap<>();
    static {
        GENDERS.put("M", "Male");
        GENDERS.put("F", "Female");
        GENDERS.put("X", "Prefer not to say");
    }

@Override
    public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        RegisterData bean = (RegisterData) request.getSession().getAttribute(BEAN_ATTR);
        if (bean == null) {
            // first visit to page
            bean = new RegisterData();
            request.getSession().setAttribute(BEAN_ATTR, bean);
            request.getSession().setAttribute(MESSAGE_ATTR, WELCOME_MESSAGE);
            request.getSession().setAttribute(COURSES_ATTR, COURSES);
            request.getSession().setAttribute(GENDERS_ATTR, GENDERS);
        }
        doPost(request, response);
    }

@Override
    public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        RegisterData bean = (RegisterData) request.getSession().getAttribute(BEAN_ATTR);
        if (bean == null) {
            // something went wrong - start over
            request.getSession().removeAttribute(BEEN_HERE_ATTR);
            response.sendRedirect(request.getRequestURI());
            return;
        }

boolean allDone = false;
        String destination = "index.jsp";
        boolean beenHereBefore = request.getSession().getAttribute(BEEN_HERE_ATTR) != null;
        
        if (beenHereBefore) {
            bean.setName(request.getParameter("user_name"));
            bean.setPassword(request.getParameter("user_password"));
            bean.setEmail(request.getParameter("user_email"));
            bean.setGender(request.getParameter("user_gender"));
            bean.setCourse(request.getParameter("user_course"));

allDone = request.getParameter("conditiontocheck") != null;
            if (allDone) {
                request.getSession().setAttribute(MESSAGE_ATTR, REGISTERED_MESSAGE);
                destination = "display.jsp";
            } else {
                request.getSession().setAttribute(MESSAGE_ATTR, NOT_AGREED_MESSAGE);
            }
        } else {
            // form has not been presented yet - no processing to perform
            request.getSession().setAttribute(BEEN_HERE_ATTR, ""); // mark been here
        }

request.getRequestDispatcher(destination).forward(request, response);
    }
}

RegisterData

package com.packages.beans;

public class RegisterData {

private String name;
    private String password;
    private String email;
    private String gender;
    private String course;

public RegisterData() {
        // set defaults here
        this.name = "";
        this.password = "";
        this.email = "";
        this.gender = "";
        this.course = "";
    }

public String getName() {
        return this.name;
    }

public void setName(String name) {
        this.name = name;
    }

public String getPassword() {
        return this.password;
    }

public void setPassword(String password) {
        this.password = password;
    }

public String getEmail() {
        return this.email;
    }

public void setEmail(String email) {
        this.email = email;
    }

public String getGender() {
        return this.gender;
    }

public void setGender(String gender) {
        this.gender = gender;
    }

public String getCourse() {
        return this.course;
    }

public void setCourse(String course) {
        this.course = course;
    }

public RegisterData name(String name) {
        setName(name);
        return this;
    }

public RegisterData password(String password) {
        setPassword(password);
        return this;
    }

public RegisterData email(String email) {
        setEmail(email);
        return this;
    }

public RegisterData gender(String gender) {
        setGender(gender);
        return this;
    }

public RegisterData course(String course) {
        setCourse(course);
        return this;
    }

@Override
    public String toString() {
        return "{" +
                " name='" + getName() + "'" +
                ", password='" + getPassword() + "'" +
                ", email='" + getEmail() + "'" +
                ", gender='" + getGender() + "'" +
                ", course='" + getCourse() + "'" +
                "}";
    }

}

web.xml
index.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8" %>
<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<!DOCTYPE html>
<html>
  <head>
    <title>Form</title>
    <style>
      .container {
        width: 60%;
        border: 1px solid black;
        margin: auto;
        padding: 20px;
        font-size: 20px;
      }

#my-form tr td input {
        font-size: 20px;
      }
    </style>
  </head>

<body>
    <div class="container">
      <h1>My Form</h1>
      <h3>${message}</h3>
      <form id="my-form" method="post">
        <table>
          <tr>
            <td>
              Name:
            </td>
            <td>
              <input type="text" name="user_name" placeholder="Enter your name"
                value="${bean.name}" />
            </td>
          </tr>
          <tr>
            <td>
              Password:
            </td>
            <td>
              <input type="password" name="user_password" placeholder="Enter your password"
                value="${bean.password}" />
            </td>
          </tr>
          <tr>
            <td>
              Email:
            </td>
            <td>
              <input type="email" name="user_email" placeholder="Enter your email"
                value="${bean.email}" />
            </td>
          </tr>
          <tr>
            <td>
              Gender:
            </td>
            <td>
              <c:forEach items="${genders}" var="gender">
                <c:choose>
                  <c:when test="${bean.gender eq gender.key}">
                    <input type="radio" name="user_gender" value="${gender.key}"
                      checked="checked">${gender.value}
                  </c:when>
                  <c:otherwise>
                    <input type="radio" name="user_gender" value="${gender.key}">${gender.value}
                  </c:otherwise>
                </c:choose>
              </c:forEach>
            </td>
          </tr>
          <tr>
            <td>
              Course:
            </td>
            <td>
              <select name="user_course">
                <c:forEach items="${courses}" var="course">
                  <c:choose>
                    <c:when test="${bean.course eq course}">
                      <option value="${course}" selected>${course}</option>
                    </c:when>
                    <c:otherwise>
                      <option value="${course}">${course}</option>
                    </c:otherwise>
                  </c:choose>
                </c:forEach>
              </select>
            </td>
          </tr>
          <tr style="text-align:center">
            <td>
              <input type="checkbox" value="checked" name="conditiontocheck" />
            </td>
            <td>
              Agree terms and conditions
            </td>
          </tr>
          <tr style="text-align:center">
            <td>
            </td>
            <td>
              <button type="submit">Register</button>
              <button type="reset">Reset</button>
            </td>
          </tr>
        </table>
      </form>
    </div>
  </body>
</html>

display.jsp
pom.xml

<dependencies>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>4.0.1</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>org.glassfish.web</groupId>
            <artifactId>jstl-impl</artifactId>
            <version>1.2</version>
            <scope>runtime</scope>
        </dependency>
    </dependencies>
    <build>
        <finalName>web</finalName>
    </build>
</project>

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