CMIS440-model2-controller.java

package web;
//Business logic component imports
import domain.Course;
import domain.Student;
import domain.RegisterService;
//Servlet imports
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.ServletContext;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
//Support classes
import util.Status;
import java.io.IOException;
import java.util.Properties;
public class RegistrationServlet extends HttpServlet {
   public void doPost(HttpServletRequest request, 
         HttpServletResponse response) throws IOException, ServletException {
      //Dispatch the request
      processRequest(request, response);
   }
   //The method that performs the Control aspects of the Web application
   public void processRequest(HttpServletRequest request, 
      HttpServletResponse response) throws IOException, ServletException {
      //Declare the dispatcher for the View
      RequestDispatcher view=null; 
      //Create the business logic object
      RegisterService regService=null;
      //Create the Status object and store it in the request 
      //for use by the 'Registration Form' View (if necessary)
      Status status=new Status();
      request.setAttribute("status", status);
      //Retrieve the HTML form parameters
      String semester=request.getParameter("semester");
      String number=request.getParameter("number");
      String name=request.getParameter("name");
      String address=request.getParameter("address");
      String city=request.getParameter("city");
      String state=request.getParameter("state");
      String zipCode=request.getParameter("zipCode");
      //Verify form fields data; create Exception objects if data are missing
      //These "error messages" are presented to the user 
      //in a red bulleted list
      if (semester.equals("unknown"))
         status.addException(new Exception(
            "Please select a course semester. "));
      if (number.equals("unknown")) 
         status.addException(new Exception(
            "Please select a course number. "));
      if ((name==null) || (name.length()==0))
         status.addException(new Exception("Please enter your name. "));
      if (   (address==null)    || (address.length()==0)
          || (city==null)       || (city.length()==0)
          || (state==null)      || (state.length()==0)
          || (zipCode==null)    || (zipCode.length()==0) )
         status.addException(new Exception(
            "Please enter your full address. "));
      //In case of errors, forward the request back to 
      //'Registration Form' View 
      //and return without proceeding with the rest of 
      //the business logic.
      if (!status.isSuccessful()) {
         view=request.getRequestDispatcher("form.jsp");
         view.forward(request, response);
         return;
      }
      //If no verification errors are found, the Controller
      //uses the business services to perform the registration.
      try {
         Properties sysprops=System.getProperties();
         String fs=sysprops.getProperty("file.separator");
         String path=getServletContext().getRealPath("/")+
                "WEB-INF/storage"+fs;
         regService=new RegisterService();
         //Retrieve the Course object and verify that it exists
         Course course=regService.getCourse(semester, number, path);
         if (course==null) throw new Exception("The course you have "+
               " selected does not yet exist; please select another one.");
         //Create and populate the student object
         Student student=regService.createStudent(
            name,address,city,state,zipCode);
         //Delegate registration to the RegisterService object
         regService.register(course, student, path);
         request.setAttribute("course", course);
         request.setAttribute("student", student);
         //Select the next View for the user in case 
         //registration is successful
         //Forward to the thankYou.jsp View
         view=request.getRequestDispatcher("thankYou.jsp");
         view.forward (request, response);
      } 
      //Select the next View for the user in case of business logic errors.
      //Forward back to the 'Registration Form' View to report 
      //what errors occurred. 
      catch (Exception e) {
         status.addException(e);
         //Select next View.
         //Exceptions are caught, forward back to the form.jsp View.
         view=request.getRequestDispatcher("form.jsp");
         view.forward(request, response);
      }
   }
}