孙卫琴：精通struts helloapp源码 第一到四章

package hello; import javax.servlet.RequestDispatcher; import javax.servlet.ServletException; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpSession; import javax.servlet.http.HttpServletResponse; import org.apache.struts.action.Action; import org.apache.struts.action.ActionMessage; import org.apache.struts.action.ActionMessages; import org.apache.struts.action.ActionForm; import org.apache.struts.action.ActionForward; import org.apache.struts.action.ActionMapping; import org.apache.struts.util.MessageResources; public final class HelloAction extends Action { /** * Process the specified HTTP request, and create the corresponding HTTP * response (or forward to another web component that will create it). * Return an <code>ActionForward</code> instance describing where and how * control should be forwarded, or <code>null</code> if the response has * already been completed. */ public ActionForward execute(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response) throws Exception { // These "messages" come from the ApplicationResources.properties file MessageResources messages = getResources(request); /* * Validate the request parameters specified by the user * Note: Basic field validation done in HelloForm.java * Business logic validation done in HelloAction.java */ ActionMessages errors = new ActionMessages(); String userName = (String)((HelloForm) form).getUserName(); String badUserName = "Monster"; if (userName.equalsIgnoreCase(badUserName)) { errors.add("username", new ActionMessage("hello.dont.talk.to.monster", badUserName )); saveErrors(request, errors); return (new ActionForward(mapping.getInput())); } /* * Having received and validated the data submitted * from the View, we now update the model */ PersonBean pb = new PersonBean(); pb.setUserName(userName); pb.saveToPersistentStore(); /* * If there was a choice of View components that depended on the model * (or some other) status, we'd make the decision here as to which * to display. In this case, there is only one View component. * * We pass data to the View components by setting them as attributes * in the page, request, session or servlet context. In this case, the * most appropriate scoping is the "request" context since the data * will not be neaded after the View is generated. * * Constants.PERSON_KEY provides a key accessible by both the * Controller component (i.e. this class) and the View component * (i.e. the jsp file we forward to). */ request.setAttribute( Constants.PERSON_KEY, pb); // Remove the Form Bean - don't need to carry values forward request.removeAttribute(mapping.getAttribute()); // Forward control to the specified success URI return (mapping.findForward("SayHello")); } }