<div id="login">
		<h2>用户登陆</h2>
		<form method="post" action="LoginServlet" οnsubmit="return check()">
			<dl>
				<dt>用户名：</dt>
				<dd><input class="input-text" type="text" id="username" name="username" οnblur="isUsernameNull()"/><span id="usernull"></span></dd>
				<dt>密　码：</dt>
				<dd><input class="input-text" type="password" id="password" name="password" οnblur="isPasswordNull()"/><span  id="pwdnull"></span></dd>
				<dt> </dt>
				<dd class="button"><input class="input-btn" type="submit" name="submit" value="" />
				<input class="input-reg" type="button" name="register" 
				value="" οnclick="window.location='register.jsp';" /></dd>
			</dl>
		</form>
	</div>

LoginServlet的参考代码：

public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		String username = request.getParameter("username");
		String password = request.getParameter("password");
		
		UserinfoDao ud = new UserinfoDaoImpl();
		
		Userinfo userinfo = ud.findByNameAndPwd(username, password);
		//如果登陆成功，则去bookListServlet
		if(userinfo!=null){
			request.getSession().setAttribute("userinfo", userinfo);
			response.sendRedirect("BooklistServlet");
		}
		else{
			response.sendRedirect("login.jsp");
		}
		
	}

protected void doPost(HttpServletRequest req, HttpServletResponse resp)
			throws ServletException, IOException {
		String page = req.getParameter("page");
		if(page==null){
			page="1";//第一次传过来就是默认首页
		}
		int pageindex = Integer.parseInt(page);//否则，可能是第2页等
		BookDao bd = new BookDaoImpl();
		List<Book> books = bd.findBookByPage(pageindex, 3);//3：每页多少数据
		int count = bd.count();
		PageControler pc = new PageControler();
		int total = pc.getTotalPages(count, 3);//总页数
		//通过request设置属性,+forward转向；
		
		req.setAttribute("pageindex", pageindex);
//		HttpSession session=req.getSession();
//		session.setAttribute("books",books); 也可以，可以直接跳转;
		req.setAttribute("books",books);
		req.setAttribute("total",total);
		
		req.getRequestDispatcher("index.jsp").forward(req,resp);
	}

<div id="content" class="wrap">
	<div class="list bookList">
		<form method="post" name="shoping" action="CartServlet" οnsubmit="return checkCart();">
			<table>
				<tr>
					<th class="checker">@</th>
					<th>书名</th>
					<th class="info">简介</th>
					<th class="price">价格</th>
					<th class="store">库存</th>
					<th class="view">图片预览</th>
				</tr>
					<c:forEach items="" var="book"><!--book.id的值可以存放value -->
					<tr>
						<td><input type="checkbox" name="bookId" value="" /></td>
						<td class="title"></td>
						<td class="info"></td>
						<td>￥</td>
						<td></td>
						<td class="thumb"><img src="images/book/" /></td>
					</tr>
					</c:forEach>
					
				
			</table>
			
			<div class="page-spliter">
				<a href="https://www.ctyun.cn/portal/link.html?target=BooklistServlet%3Fpage%3D1">首页</a>
					
				<c:if test="">
					<a href="https://www.ctyun.cn/portal/link.html?target=BooklistServlet%3Fpage%3D%24%7Bpageindex-1%7D">上一页</a>
				</c:if>
				
				<c:if test="">
					<a href="https://www.ctyun.cn/portal/link.html?target=BooklistServlet%3Fpage%3D%24%7Bpageindex%2B1%7D">下一页</a>
				</c:if>
					
				<a href="https://www.ctyun.cn/portal/link.html?target=BooklistServlet%3Fpage%3D%24%7Btotal%7D">尾页</a>
			</div>
			
			<div class="button">
			<input class="input-btn" type="submit"
			 name="submit" value="" /></div>
		</form>
	</div>
</div>