最近改写别人的Java Web项目练习，遇到这个问题卡着两三天了。

图片说明

以下是JSP代码

 <%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>


<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <title>left</title>
    <base target="body"/>
    <meta http-equiv="pragma" content="no-cache">
    <meta http-equiv="cache-control" content="no-cache">
    <meta http-equiv="expires" content="0">    
    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
    <meta http-equiv="description" content="This is my page">
    <meta http-equiv="content-type" content="text/html;charset=utf-8">
    <!--
    <link rel="stylesheet" type="text/css" href="styles.css">
    -->
    <script type="text/javascript" src="<c:url value='/jquery/jquery-1.5.1.js'/>"></script>
    <script type="text/javascript" src="<c:url value='/menu/mymenu.js'/>"></script>
    <link rel="stylesheet" href="<c:url value='/menu/mymenu.css'/>" type="text/css" media="all">
    <link rel="stylesheet" type="text/css" href="<c:url value='/jsps/css/left.css'/>">
<script language="javascript">
/*
 * 1. 对象名必须与第一个参数相同！
   2. 第二个参数是显示在菜单上的大标题
 */
var bar = new Q6MenuBar("bar", "仙林大学城网上书城");
$(function() {
    bar.colorStyle = 4;//指定配色样式，一共0,1,2,3,4
    bar.config.imgDir = "<c:url value='/menu/img/'/>";//小工具所需图片的路径
    bar.config.radioButton=true;//是否排斥，多个一级分类是否排斥

    /*
    1. 程序设计：一级分类名称
    2. Java Javascript：二级分类名称
    3. /goods/jsps/book/list.jsp：点击二级分类后链接到的URL
    4. body:链接的内容在哪个框架页中显示
    */
<c:forEach items="${parents}" var="parent">
  <c:forEach items="${parent.children}" var="child">
    bar.add("${parent.cname}", "${child.cname}", "/goods/BookServlet?method=findByCategory&cid=${child.cid}", "body");
  </c:forEach>
</c:forEach>

    $("#menu").html(bar.toString());
});
</script>
</head>

<body>  
  <div id="menu"></div>
</body>
</html>

以下servlet代码

 package cn.itcast.goods.book.web.servlet;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import cn.itcast.commons.CommonUtils;
import cn.itcast.goods.book.domain.Book;
import cn.itcast.goods.book.service.BookService;
import cn.itcast.goods.pager.PageBean;
import cn.itcast.servlet.BaseServlet;

public class BookServlet extends BaseServlet {
    private BookService bookService = new BookService();

    /**
     * 获取当前页码
     *
     * @param req
     * @return
     */
    private int getPc(HttpServletRequest req) {
        int pc = 1;
        String param = req.getParameter("pc");
        if (param != null && !param.trim().isEmpty()) {
            try {
                pc = Integer.parseInt(param);
            } catch (RuntimeException e) {
            }
        }
        return pc;
    }

    /**
     * 截取url，页面中的分页导航中需要使用它做为超链接的目标！
     *
     * @param req
     * @return
     */
    /*
     * http://localhost:8080/goods/BookServlet?methed=findByCategory&cid=xxx&pc=3
     * /goods/BookServlet + methed=findByCategory&cid=xxx&pc=3
     */
    private String getUrl(HttpServletRequest req) {
        String url = req.getRequestURI() + "?" + req.getQueryString();
        /*
         * 如果url中存在pc参数，截取掉，如果不存在那就不用截取。
         */
        int index = url.lastIndexOf("&pc=");
        if (index != -1) {
            url = url.substring(0, index);
        }
        return url;
    }

    /**
     * 按bid查询
     *
     * @param req
     * @param resp
     * @return
     * @throws ServletException
     * @throws IOException
     */
    public String load(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        String bid = req.getParameter("bid");//获取链接的参数bid
        Book book = bookService.load(bid);//通过bid得到book对象
        req.setAttribute("book", book);//保存到req中
        return "f:/jsps/book/desc.jsp";//转发到desc.jsp
    }

    /**
     * 按分类查
     *
     * @param req
     * @param resp
     * @return
     * @throws ServletException
     * @throws IOException
     */
    public String findByCategory(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        /*
         * 1. 得到pc：如果页面传递，使用页面的，如果没传，pc=1
         */
        int pc = getPc(req);
        /*
         * 2. 得到url：...
         */
        String url = getUrl(req);
        /*
         * 3. 获取查询条件，本方法就是cid，即分类的id
         */
        String cid = req.getParameter("cid");
        /*
         * 4. 使用pc和cid调用service#findByCategory得到PageBean
         */
        PageBean<Book> pb = bookService.findByCategory(cid, pc);
        /*
         * 5. 给PageBean设置url，保存PageBean，转发到/jsps/book/list.jsp
         */
        pb.setUrl(url);
        req.setAttribute("pb", pb);
        return "f:/jsps/book/list.jsp";
    }

    /**
     * 按作者查
     *
     * @param req
     * @param resp
     * @return
     * @throws ServletException
     * @throws IOException
     */
    public String findByAuthor(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        /*
         * 1. 得到pc：如果页面传递，使用页面的，如果没传，pc=1
         */
        int pc = getPc(req);
        /*
         * 2. 得到url：...
         */
        String url = getUrl(req);
        /*
         * 3. 获取查询条件，本方法就是cid，即分类的id
         */
        String author = req.getParameter("author");
        /*
         * 4. 使用pc和cid调用service#findByCategory得到PageBean
         */
        PageBean<Book> pb = bookService.findByAuthor(author, pc);
        /*
         * 5. 给PageBean设置url，保存PageBean，转发到/jsps/book/list.jsp
         */
        pb.setUrl(url);
        req.setAttribute("pb", pb);
        return "f:/jsps/book/list.jsp";
    }

    /**
     * 按出版社查询
     *
     * @param req
     * @param resp
     * @return
     * @throws ServletException
     * @throws IOException
     */
    public String findByPress(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        /*
         * 1. 得到pc：如果页面传递，使用页面的，如果没传，pc=1
         */
        int pc = getPc(req);
        /*
         * 2. 得到url：...
         */
        String url = getUrl(req);
        /*
         * 3. 获取查询条件，本方法就是cid，即分类的id
         */
        String press = req.getParameter("press");
        /*
         * 4. 使用pc和cid调用service#findByCategory得到PageBean
         */
        PageBean<Book> pb = bookService.findByPress(press, pc);
        /*
         * 5. 给PageBean设置url，保存PageBean，转发到/jsps/book/list.jsp
         */
        pb.setUrl(url);
        req.setAttribute("pb", pb);
        return "f:/jsps/book/list.jsp";
    }

    /**
     * 按图名查
     *
     * @param req
     * @param resp
     * @return
     * @throws ServletException
     * @throws IOException
     */
    public String findByBname(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        /*
         * 1. 得到pc：如果页面传递，使用页面的，如果没传，pc=1
         */
        int pc = getPc(req);
        /*
         * 2. 得到url：...
         */
        String url = getUrl(req);
        /*
         * 3. 获取查询条件，本方法就是cid，即分类的id
         */
        String bname = req.getParameter("bname");
        /*
         * 4. 使用pc和cid调用service#findByCategory得到PageBean
         */
        PageBean<Book> pb = bookService.findByBname(bname, pc);
        /*
         * 5. 给PageBean设置url，保存PageBean，转发到/jsps/book/list.jsp
         */
        pb.setUrl(url);
        req.setAttribute("pb", pb);
        return "f:/jsps/book/list.jsp";
    }


    /**
     * 多条件组合查询
     * @param req
     * @param resp
     * @return
     * @throws ServletException
     * @throws IOException
     */
    public String findByCombination(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        /*
         * 1. 得到pc：如果页面传递，使用页面的，如果没传，pc=1
         */
        int pc = getPc(req);
        /*
         * 2. 得到url：...
         */
        String url = getUrl(req);
        /*
         * 3. 获取查询条件，本方法就是cid，即分类的id
         */
        Book criteria = CommonUtils.toBean(req.getParameterMap(), Book.class);
        PageBean<Book> pb = bookService.findByCombination(criteria, pc);
        /*
         * 4. 使用pc和cid调用service#findByCategory得到PageBean
         */

        /*
         * 5. 给PageBean设置url，保存PageBean，转发到/jsps/book/list.jsp
         */
        pb.setUrl(url);
        req.setAttribute("pb", pb);
        return "f:/jsps/book/list.jsp";
    }
}

以下是web.xml相关配置

  <servlet>
    <servlet-name>BookServlet</servlet-name>
    <servlet-class>cn.itcast.goods.book.web.servlet.BookServlet</servlet-class>
  </servlet>
    <servlet-mapping>
    <servlet-name>BookServlet</servlet-name>
    <url-pattern>/BookServlet</url-pattern>
  </servlet-mapping>

相关文件位置

图片说明

HTML5在div里，class和id名为什么不可以相同？

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