Retrieve values from JDBC and use JSTL tags to call the methods

Question

Below is the code which i have written to retrieve values from the database (I have added the whole code so it will be easier for you to understand what i am trying to say h

Answer 1

Since it looks you're new to Java Web Programming, you can implement a full MVC scenario using JSP (View), Servlet (Controller) and Entities, DAOs and Service layer (Model). This is what you have:

Model:

• DBConnection as a database access class (Data access layer)
• AddRecords as your DAO class (Data access layer)

• No class as Service class (Business logic layer). For this example, let's have a RecordService class for this:

  public class RecordService {
      public RecordService() {
      }
      //since it has no real business logic, it will serve as facade
      public String[] getRecords() {
          AddRecords addRecords = new AddRecords();
          return addRecords.populateSelect();
      }
  }
  

Controller:

• No class for Controller yet. Since I assume you're using plain Java EE, you would use a Servlet (implementation based on Servlets StackOverflow wiki):

  @WebServlet("/RecordServlet")
  public class RecordsServlet extends HttpServlet {
      @Override
      protected void doGet(HttpServletRequest request, HttpServletResponse response)
          throws ServletException, IOException {
          //it will fire on a GET request (like accessing directly to the URL
          //from the browser)
          //here you should load the data for the View (JSP)
          loadData(request);
          //forward to show the view
          request.getRequestDispatcher("hello.jsp").forward(request, response);
      }
  
      @Override
      protected void doPost(HttpServletRequest request, HttpServletResponse response)
          throws ServletException, IOException {
          //it will fire on a POST request (like submitting the form using POST method)
          String selectedRecord = request.getParameter("selectedRecord");
          System.out.println(selectedRecord);
          request.setAttribute("selectedRecord", selectedRecord);
          loadData(request);
          //forward to show the view
          request.getRequestDispatcher("hello.jsp").forward(request, response);
      }
  
      //method to load the data available to select
      private void loadData(HttpServletRequest request) {
          RecordService recordService = new RecordService();
          String[] records = recordService.getRecords();
          //set the data as attribute on the request to be available on the View
          request.setAttribute("records", records);
      }
  }
  

View:

• You already have a JSP file. Since you haven't posted the name, let's call it hello.jsp. I will just adap your actual JSP code using JSTL:

  
  <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
  
  
      Please select an element:
      
          
          ${record}
          
      
      
  
      
      
          
  
          You've selected ${selectedRecord}!
      
  
  

Now, to run the example, build the project and access to it using http://localhost:8080/YourWebProjectName/RecordServlet. Also, you can set in the web.xml file:

    RecordServlet

And just run the web project.

Some notes:

• Use relevant names for the class/methods, I used RecordXXX since you had this AddRecord class (it should be RecordDAO or something more useful to code readers like UserDAO or YourEntityDAO).
• Distribute your classes through different packages. Every package should contain only relevant classes to its scope i.e. edu.home.dao for DAO classes, edu.home.service for service/business logic classes, and on...