ex6_47.txt

j2ee core design patterns

Example 6.47 	Navigation and Flow Control strategy
// Application Controller with flow control

public class ApplicationControllerImpl 
    implements ApplicationController {

  public ResponseContext handleRequest(Map requestContextMap) {
    ResponseContext responseContext = null;
    try {

      // Identify requested Order-processing operation 
      // from ContextObject
      String orderEvent =  getOrderEvent(requestContextMap);
      String orderState =  getOrderStatus(requestContextMap);

      // Create Command based on business Event and current State
      CommandAndViewFactory factory =
          CommandAndViewFactory.getInstance();
      CommandViewHandle result = factory.getCommand(
          orderEvent, orderState);

      // Instantiate Command from Indirect Handle
      Command command =
          (Command)result.getCommandHandle().newInstance();

      // Execute Business-tier Service
      responseContext = command.execute(requestContextMap);

      // set view name
      responseContext.setLogicalViewName(result.getViewName());
    } catch(Exception e) {
      // Handle Exception
    }
    return responseContext;
  }
  . . .
  private String getOrderStatus(Map requestContext) {
    String id = ((String[])requestContext.
        get(OrderStatus.STATUS_PARAM))[0];
    return id;
  }
  
  private String getOrderEvent(Map requestContext) {
    String orderEvent = ((String[])requestContext.
        get(Constants.REQ_OPCODE))[0];
    return orderEvent;
  }
}