网上图书商城项目学习笔记-012BOOK模块查询2

一、分析

> 按图名查询（模糊）（分页）
> 按作者查询（分页）
> 按出版社查询（分页）
> 按id查询
> 多条件组合查询（分页）

二、代码

1.view层

(1）gj.jsp等

 <form action="<c:url value='/BookServlet'/>" method="get">
     <input type="hidden" name="method" value="findByCombination" />
     <table align="center">
         <tr>
             <td>书名：</td>
             <td>
                 <input type="text" name="bname" />
             </td>
         </tr>
         <tr>
             <td>作者：</td>
             <td>
                 <input type="text" name="author" />
             </td>
         </tr>
         <tr>
             <td>出版社：</td>
             <td>
                 <input type="text" name="press" />
             </td>
         </tr>
         <tr>
             <td>&nbsp;</td>
             <td>
                 <input type="submit" value="搜　　索" />
                 <input type="reset" value="重新填写" />
             </td>
         </tr>
     </table>
 </form>

2.servlet层

(1）BookServlet.java

 /**
      * 按作者查
      * @param req
      * @param resp
      * @return
      * @throws ServletException
      * @throws IOException
      */
     public String findByAuthor(HttpServletRequest req, HttpServletResponse resp)
             throws ServletException, IOException {
         int currentPage = getCurrentPage(req);
         String url = getUrl(req);
         String author = req.getParameter("author");
         PageBean<Book> pb = bookService.findByAuthor(author, currentPage);
         pb.setUrl(url);
         req.setAttribute("pb", pb);
         return "f:/jsps/book/list.jsp";
     }

     /**
      * 按书名查
      * @param req
      * @param resp
      * @return
      * @throws ServletException
      * @throws IOException
      */
     public String findByBname(HttpServletRequest req, HttpServletResponse resp)
             throws ServletException, IOException {
         int currentPage = getCurrentPage(req);
         String url = getUrl(req);
         String bname = req.getParameter("bname");
         PageBean<Book> pb = bookService.findByBname(bname, currentPage);
         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 {
         int currentPage = getCurrentPage(req);
         String url = getUrl(req);
         String press = req.getParameter("press");
         PageBean<Book> pb = bookService.findByPress(press, currentPage);
         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 {
         int currentPage = getCurrentPage(req);
         String url = getUrl(req);
         Book criteria = CommonUtils.toBean(req.getParameterMap(), Book.class);
         PageBean<Book> pb = bookService.findByCombination(criteria, currentPage);
         pb.setUrl(url);
         req.setAttribute("pb", pb);
         return "f:/jsps/book/list.jsp";
     }

     /**
      * 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");
         Book book = bookService.load(bid);
         req.setAttribute("book", book);
         return "f:/jsps/book/desc.jsp";
     }

3.service层

(1）BookService.java

 /**
      * 按书名查
      * @param bname
      * @param currentPage
      * @return
      */
     public PageBean<Book> findByBname(String bname, int currentPage) {
         try {
             return bookDao.findByBname(bname, currentPage);
         } catch (SQLException e) {
             throw new RuntimeException(e);
         }
     }

     /**
      * 按作者查
      * @param author
      * @param currentPage
      * @return
      */
     public PageBean<Book> findByAuthor(String author, int currentPage) {
         try {
             return bookDao.findByAuthor(author, currentPage);
         } catch (SQLException e) {
             throw new RuntimeException(e);
         }
     }

     /**
      * 按出版社查
      * @param author
      * @param currentPage
      * @return
      */
     public PageBean<Book> findByPress(String press, int currentPage) {
         try {
             return bookDao.findByPress(press, currentPage);
         } catch (SQLException e) {
             throw new RuntimeException(e);
         }
     }

     /**
      * 多条件组合查询
      * @param criteria
      * @param currentPage
      * @return
      */
     public PageBean<Book> findByCombination(Book criteria, int currentPage) {
         try {
             return bookDao.findByCombination(criteria, currentPage);
         } catch (SQLException e) {
             throw new RuntimeException(e);
         }
     }

     /**
      * 加载图书
      * @param bid
      * @return
      */
     public Book load(String bid) {
         try {
             return bookDao.findById(bid);
         } catch (SQLException e) {
             throw new RuntimeException(e);
         }
     }

4.dao层

(1）BookDao.java

     /**
      * 按书名模糊查询
      * @param bname
      * @param currentPage
      * @return
      * @throws SQLException
      */
     public PageBean<Book> findByBname(String bname, int currentPage) throws SQLException {
         List<Expression> exprList = new ArrayList<Expression>();
         exprList.add(new Expression("bname", "like", "%" + bname + "%"));
         return findByCriteria(exprList, currentPage);
     }

     /**
      * 按作者查
      * @param author
      * @param currentpage
      * @return
      * @throws SQLException
      */
     public PageBean<Book> findByAuthor(String author, int currentpage) throws SQLException {
         List<Expression> exprList = new ArrayList<Expression>();
         exprList.add(new Expression("author", "like", "%" + author + "%"));
         return findByCriteria(exprList, currentpage);
     }

     /**
      * 按出版社查
      * @param press
      * @param currentpage
      * @return
      * @throws SQLException
      */
     public PageBean<Book> findByPress(String press, int currentpage) throws SQLException {
         List<Expression> exprList = new ArrayList<Expression>();
         exprList.add(new Expression("press", "like", "%" + press + "%"));
         return findByCriteria(exprList, currentpage);
     }

     /**
      * 多条件组合查询
      * @param criteria
      * @param currentPage
      * @return
      * @throws SQLException
      */
     public PageBean<Book> findByCombination(Book criteria, int currentPage) throws SQLException {
         List<Expression> exprList = new ArrayList<Expression>();
         exprList.add(new Expression("bname", "like", "%" + criteria.getBname() + "%"));
         exprList.add(new Expression("author", "like", "%" + criteria.getAuthor() + "%"));
         exprList.add(new Expression("press", "like", "%" + criteria.getPress() + "%"));
         return findByCriteria(exprList, currentPage);
     }

     /**
      * 通用的查询方法
      * @param exprList
      * @param currentPage
      * @return
      * @throws SQLException
      */
     private PageBean<Book> findByCriteria(List<Expression> exprList,
             int currentPage) throws SQLException {
         /*
          * 1. 得到pageSize
          * 2. 得到totalRecords
          * 3. 得到beanList
          * 4. 创建PageBean，返回
          */
         /*
          * 1. 得到pageSize
          */
         int pageSize = PageConfig.BOOK_PAGE_SIZE;
         /*
          * 2. 通过exprList来生成where子句
          */
         StringBuilder whereSql = new StringBuilder(" where 1=1");
         List<Object> params = new ArrayList<Object>();
         for(Expression expr : exprList) {
             /*
              * 添加一个条件上，
              * 1) 以and开头
              * 2) 条件的名称
              * 3) 条件的运算符，可以是=、!=、>、< ... is null，is null没有值
              * 4) 如果条件不是is null，再追加问号，然后再向params中添加一与问号对应的值
              */
             whereSql.append(" and ").append(expr.getName())
                 .append(" ").append(expr.getOperator()).append(" ");
             // where 1=1 and bid = ?
             if(!expr.getOperator().equalsIgnoreCase("is null")) {
                 whereSql.append("?");
                 params.add(expr.getValue());
             }
         }

         /*
          * 3. 总记录数
          */
         String sql = "select count(*) from t_book" + whereSql;
         Number count = (Number) qr.query(sql, new ScalarHandler(), params.toArray());
         int totalRecords = count.intValue();//得到了总记录数
         /*
          * 4. 得到beanList，即当前页记录
          */
         sql = "select * from t_book" + whereSql + " order by orderBy limit ?,?";
         params.add((currentPage - 1) * pageSize);//当前页首行记录的下标
         params.add(pageSize);//每页记录数

         List<Book> beanList = qr.query(sql, new BeanListHandler<Book>(Book.class), params.toArray());

         /*
          * 5. 创建PageBean，设置参数
          */
         PageBean<Book> pb = new PageBean<Book>();
         /*
          * 其中PageBean没有url，这个任务由Servlet完成
          */
         pb.setBeanList(beanList);
         pb.setCurrentPage(currentPage);
         pb.setPageSize(pageSize);
         pb.setTotalRecords(totalRecords);

         return pb;
     }

     /**
      * 按bid查询
      * @param bid
      * @return
      * @throws SQLException
      */
     public Book findById(String bid) throws SQLException {
         String sql = "select * from t_book where bid=?";
         return qr.query(sql, new BeanHandler<Book>(Book.class), bid);
     }