Hi there I am fairly new to building web pages using JSP and servlets and I'm trying to use switch statements to run functions depending on the link/button the user clicks but every code I've tried fails to run the function or redirect to new page, any help would be appreciated i tried using html tag and request.getContextPath but no avail... it returns 404 error or returns a blank page
Here is my servlet code
public class StudentServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
private StudentDao studentDao;
public StudentServlet() {
this.studentDao = new StudentDao();
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String sPath = request.getServletPath();
//switch statement to call appropriate method
switch (sPath) {
case "/new":
try {
showNewForm(request, response);
} catch (ServletException | IOException e) {
e.printStackTrace();
}
break;
case "/insert":
try {
insertStudent(request, response);
} catch (SQLException | IOException e) {
e.printStackTrace();
}
break;
case "/delete":
try {
deleteStudent(request, response);
} catch (SQLException | IOException e) {
e.printStackTrace();
}
break;
case "/update":
try {
updateStudent(request, response);
} catch (SQLException | IOException e) {
e.printStackTrace();
}
break;
case "/edit":
try {
editStudent(request, response);
} catch (ServletException | IOException e) {
e.printStackTrace();
}
default:
try {
listAllStudents(request, response);
} catch (ServletException | IOException | SQLException e) {
e.printStackTrace();
}
break;
}
}
// functions to fetch data from studentDao and display data on appropriate jsp
private void listAllStudents(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException, SQLException {
List<Student> allStudents = studentDao.selectAllStudents();
request.setAttribute("listStudents", allStudents);
RequestDispatcher dispatch = request.getRequestDispatcher("student-list.jsp"); //home page week04/StudentServlet | list all objects from table
dispatch.forward(request, response);
}
private void showNewForm(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
RequestDispatcher dispatch = request.getRequestDispatcher("student-form.jsp");
dispatch.forward(request, response);
}
private void insertStudent(HttpServletRequest request, HttpServletResponse response)
throws SQLException, IOException{
String name = request.getParameter("name");
String email = request.getParameter("email");
Student newStudent = new Student(name, email);
studentDao.insertStudent(newStudent); //student object inserted to table
response.sendRedirect("listStudents"); //redirect to home page
}
private void deleteStudent(HttpServletRequest request, HttpServletResponse response)
throws SQLException, IOException {
int id = Integer.parseInt(request.getParameter("id"));
studentDao.deleteStudent(id); //student object deleted
response.sendRedirect("listStudents");
}
private void updateStudent(HttpServletRequest request, HttpServletResponse response)
throws SQLException, IOException{
int id = Integer.parseInt(request.getParameter("id"));
String name = request.getParameter("name");
String email = request.getParameter("email");
Student updateStudent = new Student(id, name, email);
studentDao.updateStudent(updateStudent); //student object updated
response.sendRedirect("listStudents");
}
private void editStudent(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
int id = Integer.parseInt(request.getParameter("id"));
Student currentStudent = studentDao.selectStudent(id);
RequestDispatcher dispatch = request.getRequestDispatcher("student-form.jsp");
request.setAttribute("student", currentStudent); //student object updated
dispatch.forward(request, response);
}
}
and here is my jsp page
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1" import="java.util.*" import="week04.model.Student"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, intial-scale=1 shink-to-fit=yes">
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/[email protected]/dist/css/bootstrap.min.css"
integrity="sha384-... " crossorigin="anonymous">
</head>
<body>
<div class="container-fluid">
<nav class="navbar navbar-dark bg-primary pd-8">
<a class="navbar-brand">XYZ University</a>
</nav>
<div class="container">
<div class="container-fluid p-4">
<a href="/new" class="btn btn-success" action="/new">Add
Student</a>
</div>
<br>
<!--Assigning ArrayList object containing student data to the local object -->
<% ArrayList<Student> studentList = (ArrayList) request.getAttribute("listStudents"); %>
<table class="table table-bordered">
<thead>
<tr>
<th>ID</th>
<th>Name</th>
<th>Email</th>
<th>Actions</th>
</tr>
</thead>
<tbody>
<%
if(request.getAttribute("listStudents") != null) {
Iterator<Student> iterator = studentList.iterator();
while(iterator.hasNext()) {
Student studentDetails = iterator.next();
%>
<tr><td><%=studentDetails.getId()%></td>
<td><%=studentDetails.getName()%></td>
<td><%=studentDetails.getEmail()%></td>
<td><a href="<%=request.getContextPath()%>/update">Update</a>
<a href="<%=request.getContextPath()%>/delete">Delete</a></td>
</tr>
<%
}
}
%>
</tbody>
</table>
</div>
</div>
</body>
</html>
and here is my xml file
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:web="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd http://java.sun.com/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee" id="WebApp_ID" version="2.4">
<servlet>
<description></description>
<display-name>StudentServlet</display-name>
<servlet-name>StudentServlet</servlet-name>
<servlet-class>week04.web.StudentServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>StudentServlet</servlet-name>
<url-pattern>/StudentServlet</url-pattern>
</servlet-mapping>
</web-app>
Any help on what i'm doing wrong would be appreciated.
You need to tell the servlet in the web.xml that it processes the specified URLs.
<servlet-mapping>
<servlet-name>StudentServlet</servlet-name>
<url-pattern>/StudentServlet</url-pattern>
<url-pattern>/new</url-pattern>
</servlet-mapping>
Additionally, href must be specified correctly.
<div class="container-fluid p-4">
<a href="new" class="btn btn-success" action="/new">Add Student</a>
</div>