Servlet中cookie保存密码的使用及利用ServletContext做网站计数器

LoginCl的代码：
public class LoginCl extends HttpServlet {
    @Override
    public void init(){
        try{
            System.out.println("initb被调用一次");
            //从文件中读
            FileReader f=new FileReader("F:\\testfile.txt");
            BufferedReader br=new BufferedReader(f);
            String str=br.readLine();
            ServletContext sc=this.getServletContext();
            sc.setAttribute("count",(Integer.parseInt(str)));
            
            
            br.close();
        }
        catch(Exception e){
            e.printStackTrace();
        }
    }
    
    @Override
    public void destroy(){
        try{
            System.out.println("destroy被调用一次");
            //向文件中写人数据
            FileWriter fw=new FileWriter("F:\\testfile.txt");
            BufferedWriter bw=new BufferedWriter(fw);
            int count=(Integer)this.getServletContext().getAttribute("count");
            bw.write(count +"");
            //注意一定要关闭
            bw.close();
        }
        catch(Exception e){
            e.printStackTrace();
        }
    }
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        Connection ct=null;
        Statement sm=null;
        ResultSet rs=null;
        try{
            String name=request.getParameter("user_name");
            String pwd=request.getParameter("user_pwd");
            Class.forName("oracle.jdbc.driver.OracleDriver");
            ct=DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:orcl","outln","outln");
            sm=ct.createStatement();
            rs=sm.executeQuery("select user_pwd from Person where user_name='"+name+"'");
            if(rs.next()){
                //进来了说明该用户存在
                if(rs.getString(1).equals(pwd)){//进来了说明密码正确
                    String check=request.getParameter("check");
                    if(check!=null){
                        
                        //在服务器创建cookie
                        Cookie n=new Cookie("user_name",name);
                        Cookie p=new Cookie("user_pwd",pwd);
                        //设置时间
                        n.setMaxAge(14 * 24 * 3600);
                        p.setMaxAge(14 * 24 * 3600);
                        
                        //回写到客户端
                        response.addCookie(n);
                        response.addCookie(p);
                    }
                    HttpSession hs=request.getSession(true);
                    
                    hs.setMaxInactiveInterval(30);
                    hs.setAttribute("name",name);
                    //hs.setAttribute("pwd",pwd);
                    //没登录一次，就把服务器ServletContext的访问次数加1
                
                    int count=(Integer)this.getServletContext().getAttribute("count");
                    this.getServletContext().setAttribute("count",(count+1));
                    response.sendRedirect("Wel");//这里要写的是你要转向的servlet的URL
                }
                else response.sendRedirect("login");//密码错误
            }
            else response.sendRedirect("login");//该用户不存在
        }
        catch(Exception e){
            e.printStackTrace();
        }
        finally{
            try{
                if(ct!=null) ct.close();
                if(sm!=null) ct.close();
                if(rs!=null) ct.close();
            }
            catch(Exception e){
                e.printStackTrace();
            }
        }
    }
            
                
        
    
    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        this.doGet(request, response);
    }

}

welcome的代码：

　　作用：防止用户非法登录，同时对两周内（这是自己设定的）保存密码的用户进行处理

public  class Wel extends HttpServlet {

    public  void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        try{
            PrintWriter pw=response.getWriter();
            //防止用户非法登录
            HttpSession hs=request.getSession();
            
            String user_name=(String)hs.getAttribute("name");
            
            String name="",pwd="";
            if(user_name==null){
                Cookie myCookie[]=request.getCookies();
                if(myCookie!=null){
                    for(int i=0;i<myCookie.length;i++){
                        if(myCookie[i].getName().equals("user_name"))
                            name=myCookie[i].getValue();
                        else if(myCookie[i].getName().equals("user_pwd"))
                            pwd=myCookie[i].getValue();
                    }
                    System.out.println("------" + name + "/" + pwd);
                    if(!name.equals("")&& !pwd.equals("")){
                        response.sendRedirect("LoginCl?user_name="+name+"&user_pwd="+pwd+"");
                        return;
                    }
                }
                response.sendRedirect("login");
            }

　　　　pw.println("您的id为:" + request.getRemoteAddr());
　　　　pw.println("您的id为:" + request.getRemoteHost());

int a=(Integer)this.getServletContext().getAttribute("count");
            pw.print(a);
        }
        catch(Exception e){
            e.printStackTrace();
        }
        
        
    }

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

        this.doGet(request,response);
    }

}