controlservlet.java

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/*
控制器
作用：
在初始化时实例“模型”，并放入上下文（保证模型有且仅有一个实例）
在收到请求时取出参数，调用模型实例完成操作，并把数据状态存放在Request中
转交数据状态到下一个视图
在自己毁灭之前，销毁资源
*/
package TestClass;

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

public class ControlServlet extends HttpServlet
{
	public void init(ServletConfig config) throws ServletException
	{
		config.getServletContext().setAttribute("toMain",new LoginCommand("/Main.jsp"));
		config.getServletContext().setAttribute("toTest",new StartCommand("/Test.jsp"));
		config.getServletContext().setAttribute("SetScore",new ScoreCommand("/End.htm"));
		config.getServletContext().setAttribute("BackTest",new NullCommand("/Login.jsp"));
		config.getServletContext().setAttribute("GetScore",new ScoreListCommand("/Score.jsp"));
		config.getServletContext().setAttribute("ReturnTest",new NullCommand("/Manager.htm"));
		config.getServletContext().setAttribute("PrintXML",new PrintCommand("/Score.jsp"));
		super.init(config);
	}
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
	{
		//取出传来的命令参数信息
		String cmd = request.getParameter("cmd");
		
		//从上下文中取出业务操作组件实例
		Command cmdObj=(Command)this.getServletContext().getAttribute(cmd);
		
		//调用模型方法，并将返回值放在request中
		String next=cmdObj.execute(request,response);
		
		//重定向页面，指定视图
		this.getServletContext().getRequestDispatcher(next).forward(request,response);
	}
	
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
	{
		doPost(request,response);
	}

	public void destroy()
	{
		this.getServletContext().removeAttribute("toMain");
		this.getServletContext().removeAttribute("toTest");
		this.getServletContext().removeAttribute("SetScore");
		this.getServletContext().removeAttribute("BackTest");
		this.getServletContext().removeAttribute("GetScore");
		this.getServletContext().removeAttribute("ReturnTest");
		this.getServletContext().removeAttribute("PrintXML");
	}

}