In my project, I forbid the user from every page only if he is already logged in. This is why I wrote the code below. When I type in the browser, for example, http: // localhost: 8080 / JSP1 / Students , I go to the login.jsp page. But after entering the login and password, only a blank page appears http: // localhost: 8080 / JSP1 / Logged , and GlassFish says that there is an exception in
if (userPath.equals("/Students")){ RequestDispatcher requestDispatcher = request.getRequestDispatcher("/Students.jsp"); requestDispatcher.forward(request, response); } java.lang.IllegalStateException: PWC1227: Cannot forward after response has been committed
Full code for doGet and doPost:
@Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { HttpSession ses = request.getSession(); String login = (String)ses.getAttribute("login"); String password = (String)ses.getAttribute("password"); if ((login==null)|(password==null)){ RequestDispatcher requestDispatcher = request.getRequestDispatcher("/login.jsp"); requestDispatcher.forward(request, response); } //Now we think that we are successfully logged in String userPath = request.getServletPath(); // System.out.println(userPath); if (userPath.equals("/Login")){ RequestDispatcher requestDispatcher = request.getRequestDispatcher("/login.jsp"); requestDispatcher.forward(request, response); } if (userPath.equals("/Students")){ RequestDispatcher requestDispatcher = request.getRequestDispatcher("/Students.jsp"); requestDispatcher.forward(request, response); } if (userPath.equals("/Student")){ RequestDispatcher requestDispatcher = request.getRequestDispatcher("/Student.jspx"); requestDispatcher.forward(request, response); } if (userPath.equals("/StudentEdit")){ RequestDispatcher requestDispatcher = request.getRequestDispatcher("/StudentEdit.jsp"); requestDispatcher.forward(request, response); } } @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // processRequest(request, response); PrintWriter out = response.getWriter(); String userPath = request.getServletPath(); System.out.println(userPath); if (request.getRequestURI().equals("/Logged")){ String Login = request.getParameter("login"); String Password = request.getParameter("password"); request.getSession().setAttribute("login", Login); request.getSession().setAttribute("password", Password); RequestDispatcher requestDispatcher = request.getRequestDispatcher("/Students.jsp"); requestDispatcher.forward(request, response); } if (userPath.equals("/addStudent")) { // System.out.println(request.getContextPath()); String Name = request.getParameter("name"); String Surname = request.getParameter("surname"); String Login = request.getParameter("login"); String Password = request.getParameter("password"); Student student = new Student(Name,Surname,Login,Password); if (student != null) { dao.insertStudent(student); } else { System.out.println("Not valid parameter!!!"); } RequestDispatcher requestDispatcher = request.getRequestDispatcher("/Students.jsp"); requestDispatcher.forward(request, response); } if (request.getRequestURI().equals("/Edit")) { System.out.println("We work with students!!!"); String delete = request.getParameter("Add_new_student"); if (delete != null){ RequestDispatcher requestDispatcher = request.getRequestDispatcher("/Student.jspx"); requestDispatcher.forward(request, response); } Enumeration parameters = request.getParameterNames(); while (parameters.hasMoreElements()) { String parameterName = (String) parameters.nextElement(); String parameterValue = request.getParameter(parameterName); String norder = parameterName.substring(parameterName.indexOf("_")+1); ArrayList<Student> curStudents = dao.getAllStudents(); int norderint = Integer.parseInt(norder); Student studentToWork = curStudents.get(norderint); String actionToDo = parameterName.substring(0, parameterName.indexOf("_")); if (actionToDo.equals("Edit")){ RequestDispatcher requestDispatcher = request.getRequestDispatcher("/StudentEdit.jsp"); ServletContext cont = request.getServletContext(); cont.setAttribute("studentToEdit", studentToWork); requestDispatcher.forward(request, response); } else { boolean attemp = dao.deleteStudent(studentToWork); if (attemp){ RequestDispatcher requestDispatcher = request.getRequestDispatcher("/Students.jsp"); requestDispatcher.forward(request, response); } else { out.println("Unsuccessfull attemp to delete a Student"); } } } } if (userPath.equals("/EditStudent")){ System.out.println("We work with StudentEdit!"); Student studentToEdit = (Student)request.getSession().getAttribute("studentToEdit"); String newName = request.getParameter("name"); String newSurname = request.getParameter("surname"); String newLogin = request.getParameter("login"); String newPassword = request.getParameter("password"); Student newStudent = new Student(newName, newSurname,newLogin,newPassword); boolean update = dao.updateStudent(studentToEdit, newStudent); if (update){ out.println("<p>You have successfully edited a Student=" + studentToEdit.toString() + " to Student="+ newStudent.toString()); } else { out.println("<p>Unsuccessful attempt to edit!</p>" ); } } }
Entrance. login.jsp is simple:
<%@page contentType="text/html" pageEncoding="UTF-8"%> <!DOCTYPE html> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>JSP Page</title> </head> <body> <form action="/JSP1/Logged" method="POST"> <table> <tr> <td>Login:</td> <td><input type="text" name="login" value=""/> </td> </tr> <tr> <td>Password </td> <td><input type="password" name="password"/> ></td> </tr> <tr> <td><input type="submit" name="OK" value="OK" /> </td> </tr> </table> </form> </body>
I can not understand what is happening.