Integrating Servlets and JSP: The Model View Controller - Java ...

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Bank Account Balances:Servlet Code32@WebServlet("/show-balance")public class ShowBalance extends HttpServlet {public void doGet(HttpServletRequest request,HttpServletResponse response)throws ServletException, IOException {String customerId = request.getParameter("customerId");CustomerLookupService service = new CustomerSimpleMap();Customer customer = service.findCustomer(customerId);request.setAttribute("customer", customer);String address;if (customer == null) {request.setAttribute("badId", customerId);address = "/WEB-INF/results/unknown-customer.jsp";} else if (customer.getBalance() < 0) {address = "/WEB-INF/results/negative-balance.jsp";} … /* normal-balance and high-balance cases*/ …}RequestDispatcher dispatcher =request.getRequestDispatcher(address);dispatcher.forward(request, response);Bank Account Balances:Beanpublic class Customer {private final String id, firstName, lastName;private final double balance;public Customer(String id,String firstName,String lastName,double balance) {this.id = id;this.firstName = firstName;this.lastName = lastName;this.balance = balance;}Since the constructor is called from Java only(never from JSP), the requirement for a zero-argconstructor is eliminated. Also, since bean stateis set only with constructor, rather than withjsp:setProperty, we can eliminate settermethods and make the class immutable.// getId, getFirstName, getLastName, getBalance. No setters.33}public double getBalanceNoSign() {return(Math.abs(balance));}
Bank Account Balances:Business Logic Interfacepublic interface CustomerLookupService {public Customer findCustomer(String id);}34Bank Account Balances:Business Logic Implementationpublic class CustomerSimpleMapimplements CustomerLookupService {private Map customers;public CustomerSimpleMap() {// Populate Map with some sample customers}35}public Customer findCustomer(String id) {if (id!=null) {return(customers.get(id.toLowerCase()));} else {return(null);}}…
Page 4 and 5: Possibilities for Handling aSingle
Page 6 and 7: Review: Beans• Java classes that
Page 8 and 9: MVC Flow of ControlHTML or JSPJava
Page 10 and 11: Request Forwarding Example20public
Page 12 and 13: Request-Based Data Sharing• Servl
Page 14 and 15: ServletContext-Based DataSharing (R
Page 18 and 19: Bank Account Balances:Input Form…
Page 20 and 21: Bank Account Balances:High Balance4
Page 22 and 23: Summary44• Request scope- A new b
Page 24 and 25: Request-Based Sharing:Business Logi
Page 26: Comparing Data-SharingApproaches: S
Page 29 and 30: ServletContext-Based Sharing:Beanpa
Page 31 and 32: © 2012 Marty HallForwarding andInc
Page 33 and 34: Using RequestDispatcher.include:Set
Page 35: © 2012 Marty HallQuestions?JSF 2,

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