创建一个servlet处理用户登录请求，如果正确将用户名保存在session中，并跳转到主页面。要求，主页面要有登录权限。

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
"-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
"Content-Type" content="text/html; charset=UTF-8">
"myservlet"method="post">
输入账号："text"name="name">
输入密码："password"name="password">
"submit"value="登录">

登录form表单。

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		request.setCharacterEncoding("utf-8");
		String name=request.getParameter("name");
		String password=request.getParameter("password");
		if(name.equals("lh")&&password.equals("123"))
		{
			request.getSession().setAttribute("name", name);
			response.sendRedirect("check.jsp");
		}
		else
		{
			response.sendRedirect("main.jsp");
		}
	}
}

servlet代码部分。

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
"-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
"Content-Type" content="text/html; charset=UTF-8">
<%
if(session.getAttribute("name")==null)
		{
	response.sendRedirect("main.jsp");
		}
%>
<%=session.getAttribute("name") %>
欢迎登录！