编写servlet，产生一个1-10的随机数，将其保存到session中，然后重定向到输入页面sendMsg.jsp，在此页面输入所猜测的数后，提交到另一个servlet判断是否正确，若不正确，转发到sendMsg.jsp，在此页面显示“大了”或“小了”的提示信息网页显示页面找不到了，若正确，则在新页面显示“答对了”。(网页版的猜数游戏)

首先创建FirstServlet，该为产生的随机数的。代码如下所示：

package Servlet;
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
public class FirstServlet extends HttpServlet {
    public void init(ServletConfig config)throws ServletException {
        super.init();
    }
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
    }
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        int msg = Integer.parseInt(request.getParameter("msg"));
        //float msg = Float.parseFloat(request.getParameter("msg"));
        HttpSession session = request.getSession();
        int num = (int) session.getAttribute("num");
        if (msg == num){
            response.sendRedirect("printfMsg.jsp");
        }else {
            String m = msg > num ? "大了" : "小了";
            request.setAttribute("m",m );
            request.getRequestDispatcher("sendMsg.jsp").forward(request,response);
        }
    }
}

接下来创建PutServlet，该为判断是否正确，代码如下所示：

package Servlet;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;
import java.util.Random;
public class PutServlet extends HttpServlet {
    public void init(ServletConfig config)throws ServletException {
        super.init();
    }
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        Random random = new Random();
        int num = random.nextInt(10)+1;
        System.out.println(num);
        HttpSession session = request.getSession();
        session.setAttribute("num", num);    //将用户名保存到session
        System.out.println(num);
        response.sendRedirect("sendMsg.jsp");        //重定向到sendMsg.jsp
    }
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
    }
}

接下来编写页面sendMsg，代码如下所示：

<%@ page contentType="text/html;charset=UTF-8" language="java" %>


    



    
    

    
    <%--    该为接收大了  还是  小了--%>
    ${m}

紧接着编写更新了猜对了页面，代码如下所示：

<%@ page contentType="text/html;charset=UTF-8" language="java" %>


    


恭喜你猜对了~
${msg}

最后编写web.xml文件，代码如下所示：

    
        de
        Servlet.FirstServlet
    
    
        de
        /ser
    
    
        dei
        Servlet.PutServlet
    
    
        dei
        /put
    

最后的运行效果先输入put回车，然后它会跳转到sendMsg页面，直到输入正确的数字才会跳转到猜对了的页面，效果图如下图所示：

当我输入9时网页显示页面找不到了，提示词为大了，

知道输入正确的数字后跳转到猜对了的页面