statemachine.java

《Java网络程序设计.rar》包括三个网络程序的源代码。

/*
*/
package org.impact.stars.control.ejb;

import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.ejb.SessionContext;

import java.util.Collection;
import java.util.HashMap;

import org.impact.stars.util.Debug;
import org.impact.stars.control.event.StarsEvent;

import org.impact.stars.control.exceptions.StarsEventException;

/**
 * This class is a Universal front back end of an application
 * which ties all EJB components together dynamically at runtime.
 *
 * This class should not be updated to handle various event types.
 * This class will use ActionControllers to handle events that require
 * processing beyond the scope of this class.
 *
 * A second option to event handling is to do so in the XML descriptor
 * itself.
 *
 * State may be stored in the attributeMap
 * Configuration of this file is via an XML descriptor.

 *
 */
public class StateMachine implements java.io.Serializable {

    private UserControllerBean usercejb;
    private ModelUpdateManager mum;
    private HashMap orderTable;
    private HashMap attributeMap;
    private HashMap controllerMap;
    private SessionContext sc;

    public StateMachine(UserControllerBean usercejb, SessionContext sc) {
        this.usercejb = usercejb;
        this.sc = sc;
        this.mum = new ModelUpdateManager();
        attributeMap = new HashMap();
        controllerMap = new HashMap();
    }

    public Collection handleEvent(StarsEvent ese) throws StarsEventException{
        String eventName = ese.getEventName();
        Debug.println("StateMachine: received event name= " + eventName);

       
        if (eventName != null) {
            Debug.println("StateMachine: processingEvent= " + eventName);
            String controllerName = getControllerName(eventName);
            Debug.println("StateMachine: process controller class = " + controllerName);
            StateController controller = null;
            try {
                 if (controllerMap.get(eventName) != null) {
                     Debug.println("Controller exists");
                     
                    controller = (StateController)controllerMap.get(eventName);
                 } else {
                     controller = (StateController)Class.forName(controllerName).newInstance();
                     Debug.println("StateMachine: loading Controller");
                     /*
                     ConceptController conceptController=(ConceptController)Class.forName(controllerName).newInstance();
                     Debug.println("Casting conceptController");
                     controller = (StateController)conceptController;
                     controller = (StateController)Class.forName("org.impact.stars.control.ejb.ConceptController").newInstance();*/
                     controllerMap.put(eventName, controller);
             }
            } catch (Exception ex) {
                Debug.println("StateMachine: error loading " + controllerName + "Exception :" + ex);
            }
            if (controller != null) {
    
                
                Debug.println("StateMachine: loaded controller " + controllerName);
                controller.init(this);
                Debug.println("StateMachine: initialzied " + controllerName);
                // do the magic
                controller.doStart();
                controller.perform(ese);
                controller.doEnd();
                Debug.println("StateMachine: sucessfully processed :" + eventName);
            }
            else
            {
                Debug.println("StateMachine: no controller found");
            }
        }
        return (mum.getUpdatedModels(ese));
    }

    private String getControllerName(String eventName) {
        // do the lookup
        Debug.println("StateMachine: looking up:" + eventName + "<");
        try {
                    InitialContext ic = new InitialContext();
                    return  (String)ic.lookup(eventName);
        } catch (javax.naming.NamingException ex) {
                   Debug.println("Controller caught: " + ex);
                    // ignore.. we are working around it below.
        }
        return null;

    }


    public void setAttribute(String key, Object value) {
        attributeMap.put(key, value);
    }

    public Object getAttribute(String key) {
        return attributeMap.get(key);
    }

    public UserControllerBean getUserControllerBean() {
        return usercejb;
    }

    public SessionContext getSessionContext() {
        return sc;
    }

}