网上图书商城项目学习笔记-033删除图书

一、流程分析

二、代码

1.view层

(1).jsp

(2).js

 

2.servlet层

(1)AdminBookServlet.java

 

    /**
     * 删除图书
     * @param req
     * @param resp
     * @return
     * @throws ServletException
     * @throws IOException
     */
    public String delete(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        String bid = req.getParameter("bid");
        /*
         * 删除图片
         */
        Book book = bookService.load(bid);
        String savepath = this.getServletContext().getRealPath("/");
        new File(savepath, book.getImage_b()).delete();
        new File(savepath, book.getImage_w()).delete();
        
        bookService.delete(bid);
        req.setAttribute("msg", "删除图书成功！");
        return "f:/adminjsps/msg.jsp";
    }

3.service层

(1).java

 

4.dao层

(1)BookDao.java

    /**
     * 删除图书
     * @param bid
     * @throws SQLException
     */
    public void delete(String bid) throws SQLException {
        String sql = "delete from t_book where bid=?";
        qr.update(sql, bid);
    }

    /**
     * 按bid查询
     * @param bid
     * @return
     * @throws SQLException
     */
    public Book findById(String bid) throws SQLException {
        String sql = "SELECT * FROM t_book b, t_category c WHERE b.cid=c.cid AND b.bid=?";
        // 一行记录中，包含了很多的book的属性，还有一个cid属性
        Map<String,Object> map = qr.query(sql, new MapHandler(), bid);
        // 把Map中除了cid以外的其他属性映射到Book对象中
        Book book = CommonUtils.toBean(map, Book.class);
        // 把Map中cid属性映射到Category中，即这个Category只有cid
        Category category = CommonUtils.toBean(map, Category.class);
        // 两者建立关系
        book.setCategory(category);
        
        // 把pid获取出来，创建一个Category parnet，把pid赋给它，然后再把parent赋给category
        if(map.get("pid") != null) {
            Category parent = new Category();
            parent.setCid((String)map.get("pid"));
            category.setParent(parent);
        }
        return book;
    }