1)如果严格按照MVC思想的话，浏览器首页访问的是控制器，然后再由控制器转发到视图

2)位于WEB-INF/目录下的资源，客户端无法直接访问，只能通过服务端转发进入3)request对象也可用于资源的转发request.getRequestDispatcher("/WEB-INF/success.html").forward(request,response);4)通过正则表达式验证中文：[\u4E00-\uFA29]+5)对于重定向而言，前后的二个Request域对象不同，如果取值不到，返回"null"，不会报错

java代码：

ModelBean

public class ModelBean {    public boolean validate(String username){        boolean flag = false;        //username.matches("[a-zA-Z0-9]+")) 用户名是数字与字母        if(username!=null && username.matches("[\u4E00-\uFA29]+")){            flag = true;        }        return flag;    }}

Demo8

import java.io.IOException;import javax.servlet.RequestDispatcher;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import cn.itcast.web.domain.ModelBean;public class Demo8 extends HttpServlet {    //NO1    public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {        //转发到view.html页面        RequestDispatcher rd = request.getRequestDispatcher("/WEB-INF/view.html");        rd.forward(request,response);    }    //NO2    public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {        request.setCharacterEncoding("UTF-8");        String username = request.getParameter("username");        ModelBean mb = new ModelBean();        boolean flag = mb.validate(username);        if(flag){            //将用户名绑定到Request域对象中            request.setAttribute("USERNAME",username);            /*转发到ListServlet.java            request                .getRequestDispatcher("/ListServlet")                .forward(request,response);            */              //重定向到ListServlet.java            response.sendRedirect("/day07/ListServlet");        }else{            request            .getRequestDispatcher("/WEB-INF/fail.html")            .forward(request,response);        }    }}

ListServlet

import java.io.IOException;import java.io.PrintWriter;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class ListServlet extends HttpServlet {    public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {        String username = (String) request.getAttribute("USERNAME");        response.setContentType("text/html;charset=UTF-8");        response.getWriter().write("欢迎"+username+"光临");    }    public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {        String username = (String) request.getAttribute("USERNAME");        response.setContentType("text/html;charset=UTF-8");        response.getWriter().write("欢迎"+username+"光临");         }}

html

view.html

          
            
    
        
     
                  
       用户登录
      
                  
       
                        
用户名
                        
                   
                   
                        
                                                                                    
                   
                 
     
    
    
  

sucess.html

          
            登录成功    

fail.html

          
            登录失败