这是我自己开发的一个MVC框架

				package dark.web.frame.command;
				
				import java.io.IOException;
				
				import javax.servlet.ServletException;
				
				
				/**
				 * Title:            异常类名处理类
				 * Description:      当前用户请求中不在Command参数，或者参数中所指定的
				 * 						类名找不到是给用户返回当前类的实例。当前类会将用户
				 * 						请求转发到unknown.jsp
				 * Copyright:        Copyright (c) 2004
				 * Company:          DIS
				 * Create Time:      2004-12-6 0:37:10
				 * @author             darkhe
				 * @version            1.0
				 */
				public class UnknownCommand extends AbstractCommand
				{
					/**
					 * @throws ServletException
					 * @throws IOException
					 * @see dark.web.frame.FrontCommand#process()
					 */
					public void process() throws ServletException, IOException
					{
						setTarget("/unknown.jsp");
						
						getRequest().setAttribute("Message", "Don't specify COMMAND parameter");		
					}
				
				
				}