Java™ Application Development on Linux - Dator

418Chapter 18Servlets: Java Pressed into ServiceTable 18.1 BudgetPro servlet actionsfunc parameterOther paramsActionNext screenbeginname, dollarsCreate a top-level account, save inthe session.mainmkacctnonenonesubacctcancelnoneGet account from session.maincreatename, dollarsGet account from session; createsubaccount.maincdnameGet account from session, look upsubaccount by name, save as currentin session.mainbacknoneGet account from session, getparent from account, save as currentin session.mainThe parsing of the parameters is very straightforward. The request parameter,part of the signature of the doGet() and doPost() methods, can be usedto retrieve the parameters we need:String act = request.getParameter("func");String name = request.getParameter("name");String dollars = request.getParameter("dollars");Notice that we always ask for all three parameters, even though we willoften use only one (act). Once we have the requested function in act, it’s justa matter of if-then-else-ing our way through the possible values and takingthe appropriate actions. We store, or retrieve, the current account in thesession manager, thereby providing continuity between browser requests(Example 18.2).The output is the page to send back to the browser. We createthat page as an object, either an AccountView or a SubPage. TheHttpServletResponse provides us with an output channel on which to write.java.io.PrintWriter out = response.getWriter();if (nextPage != null) {response.setContentType("text/html");out.println(nextPage.toString());}