commandset.java

java三层架构（MVC)实现的在线图书销售系统。其中应用到工厂

package accp.yyw.model.command;

import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.util.*;

/**
 * <p>Title: BookShop</p>
 * <p>Description: </p>
 * <p>Copyright: Copyright (c) 2005</p>
 * <p>Company: accp</p>
 * @author yyw
 * @version 1.0
 */

public class CommandSet {

        private HashMap commands;

          public CommandSet() {

             this.initCommands();
          }

          private void initCommands() {

            commands = new HashMap();

            commands.put("bookshop",new NullCommand("bookshop.jsp"));
            commands.put("registermember-null",new NullCommand("clause.jsp"));
            commands.put("agreemember-null",new NullCommand("register.jsp"));
            commands.put("disagreemember-null",new NullCommand("bookshop.jsp"));
            commands.put("insertmember",new InsertMemberCommand("bookshop.jsp"));
        }

         public ICommand lookupCommand(String cmd) throws CommandException {

                  if(cmd==null)
                          {

                          return (ICommand)commands.get("bookshop");
                         }
                  else{

                        if(commands.containsKey(cmd.toLowerCase())) {

                                  return (ICommand)commands.get(cmd.toLowerCase());
                          }
                          else{

                                  throw new CommandException("Invalid Command Identifier !");
                          }
                      }
        }
}