老师我这哪里错了？

来源：2-6 自由编程

一心励志当码农

2019-10-15 16:15:22

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
	<form action="/direct/direct/check">
		<input name="num" placeholder="请输入100以内的数字">
		<input type="submit" value="求累加和">
	</form>
</body>
</html>

package com.imooc.servlet;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet implementation class CheckLoginServlet
 */
@WebServlet("/direct/check")
public class CheckLoginServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public CheckLoginServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
			request.setCharacterEncoding("utf-8");
			response.setCharacterEncoding("utf-8");
			response.setContentType("text/html;charset=utf-8");
			String num=request.getParameter("num");
			int numb=Integer.parseInt(num);
			int sum=0;
			for(int i=1;i<numb;i++) {
				sum=sum+i;
			}
			request.setAttribute("sum", sum);
			request.getRequestDispatcher("/direct/index").forward(request, response);
	}

}

package com.imooc.servlet;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet implementation class IndexServlet
 */
@WebServlet("/direct/index")
public class IndexServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public IndexServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		int sum=(int)request.getAttribute("sum");
		String html="<p>累加和为："+sum+"</p>";
		PrintWriter out=response.getWriter();
		out.println(html);
	}

}