controler.java

mvc架构的Java程序

package com.mvc.controler;

import java.io.IOException;
import java.util.Enumeration;
import java.util.ResourceBundle;
import java.util.HashMap;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import com.mvc.constant.Constant;
import com.mvc.event.baseEvent.EventHandlerBase;

public class Controler
  extends HttpServlet{
  private HashMap eventMap = new HashMap();

  public void init()
    throws ServletException{
    ResourceBundle bundle = ResourceBundle.getBundle(Constant.EVENT_PROPERTYFILE);

    Enumeration e = bundle.getKeys();

    while( e.hasMoreElements() ){
      String key = ( String )e.nextElement();
      String value = bundle.getString( key );

      try{
        EventHandlerBase event =
          ( EventHandlerBase )Class.forName( value ).newInstance();

        eventMap.put( key, event );
      }catch( Exception exc ){
        System.out.println("init error");
      }
    }
  }

  public void doGet( HttpServletRequest request, HttpServletResponse response )
    throws IOException,
           ServletException{
    doPost( request, response );
  }

  public void doPost( HttpServletRequest request, HttpServletResponse response )
    throws IOException,
           ServletException{
    String event = validateEvent( request );

    EventHandlerBase eventHandler = getEventHandler( event );

    try{
      eventHandler.process( request, response );
    }catch( Exception e ){
      request.setAttribute( Constant.ERROR, e );
      eventHandler = getEventHandler( Constant.ERROREVENT );
    }

    eventHandler.forward( request, response );
  }

  protected String validateEvent( HttpServletRequest request ){
    String eventName = request.getParameter( Constant.EVENT );

    if( eventName == null || !eventMap.containsKey( eventName ) ){
      eventName = Constant.UNKNOWEVENT;
    }

    return eventName;
  }

  protected EventHandlerBase getEventHandler( String eventName ){
    EventHandlerBase eventHandler = null;

    try{
      eventHandler =( EventHandlerBase )eventMap.get( eventName );
    }catch( Exception e ){
      eventHandler =( EventHandlerBase )eventMap.get( Constant.UNKNOWEVENT );
    }

    return eventHandler;
  }
}