Online book Store Project study notes-030 Delete level two categories

First, process analysis

Second, the Code

1.view Layer

and a same

2.servlet Layer

(1) Admincategoryservlet.java

1     /**2 * Delete Level two classification3      * @paramreq4      * @paramresp5      * @return6      * @throwsservletexception7      * @throwsIOException8      */9      PublicString Deletechild (httpservletrequest req, HttpServletResponse resp)Ten             throwsservletexception, IOException { OneString cid = Req.getparameter ("CID"); A         intCount =bookservice.findbookcountbycategory (CID); -         if(Count > 0) { -Req.setattribute ("Code", "Eror"); theReq.setattribute ("msg", "There are books under this category, cannot be deleted!") "); -             return"/adminjsps/msg.jsp"; -         } - Service.delete (CID); +         returnFindAll (req, resp); -}

3.service Layer

(1) Admincategory.java

1     /**2 * Delete Category3      * @paramCID4      */5      Public voidDelete (String cid) {6         Try {7 Categorydao.delete (CID);8}Catch(SQLException e) {9             Throw NewRuntimeException (e);Ten         } One}

(2) Bookservice.java  

1     /**2 * Query the number of books under a category3      * @paramCID4      * @return5      */6      Public intfindbookcountbycategory (String CID) {7         Try {8             returnbookdao.findbookcountbycategory (CID);9}Catch(SQLException e) {Ten             Throw NewRuntimeException (e); One         } A}

4.dao Layer

(1) Admincategorydao.java

1     /**2 * Delete Category3      * @paramCID4      * @throwsSQLException5      */6      Public voidDelete (String CID)throwsSQLException {7String sql = "Delete from t_category where cid=?";8 qr.update (SQL, CID);9}

(2) Bookdao

1     /**2 * Query the number of books under a category3      * @paramCID4      * @return5      * @throwsSQLException6      */7      Public intFindbookcountbycategory (String CID)throwsSQLException {8String sql = "SELECT COUNT (*) from T_book where cid=?";9Number count = (number) qr.query (SQL,NewScalarhandler (), CID);Ten         returnCount = =NULL? 0: Count.intvalue (); One}

Web Book Mall Project study notes-030 Delete level two categories