三层架构增删改查功能

ppublic interface BrandMapper {

    /**
     * 查询所有
     * @return
     */
    @Select("select * from tb_brand")
    @ResultMap("brandResultMap")
    List<Brand> selectAll();

    @Insert("insert into tb_brand values(null,#{brandName},#{companyName},#{ordered},#{description},#{status})")
    void add(Brand brand);

    /**
     * 根据id查询
     * @param id
     * @return
     */
    @Select("select * from tb_brand where id = #{id}")
    @ResultMap("brandResultMap")
    Brand selectById(int id);

    /**
     * 修改
     * @param brand
     */
    @Update("update tb_brand set brand_name = #{brandName},company_name = #{companyName},ordered = #{ordered},description = #{description},status = #{status} where id = #{id}")
    void update(Brand brand);

    @Delete("delete from tb_brand where id=#{id}")
    void deleteById(int id);
service：

public class BrandService {
    SqlSessionFactory factory = SqlSessionFactoryUtils.getSqlSessionFactory();


    /**
     * 查询所有
     * @return
     */
    public List<Brand> selectAll(){
        //调用BrandMapper.selectAll()

        //2. 获取SqlSession
        SqlSession sqlSession = factory.openSession();
        //3. 获取BrandMapper
        BrandMapper mapper = sqlSession.getMapper(BrandMapper.class);

        //4. 调用方法
        List<Brand> brands = mapper.selectAll();

        sqlSession.close();

        return brands;
    }

    /**
     * 添加
     * @param brand
     */
    public void add(Brand brand){

        //2. 获取SqlSession
        SqlSession sqlSession = factory.openSession();
        //3. 获取BrandMapper
        BrandMapper mapper = sqlSession.getMapper(BrandMapper.class);

        //4. 调用方法
        mapper.add(brand);

        //提交事务
        sqlSession.commit();
        //释放资源
        sqlSession.close();

    }



    /**
     * 根据id查询
     * @return
     */
    public Brand selectById(int id){
        //调用BrandMapper.selectAll()

        //2. 获取SqlSession
        SqlSession sqlSession = factory.openSession();
        //3. 获取BrandMapper
        BrandMapper mapper = sqlSession.getMapper(BrandMapper.class);

        //4. 调用方法
        Brand brand = mapper.selectById(id);

        sqlSession.close();

        return brand;
    }


    /**
     * 修改
     * @param brand
     */
    public void update(Brand brand){

        //2. 获取SqlSession
        SqlSession sqlSession = factory.openSession();
        //3. 获取BrandMapper
        BrandMapper mapper = sqlSession.getMapper(BrandMapper.class);

        //4. 调用方法
        mapper.update(brand);

        //提交事务
        sqlSession.commit();
        //释放资源
        sqlSession.close();

    }

 /**
     * 删除
     * @param brand
     */

    public void deleteById(int id){
        //2. 获取SqlSession
        SqlSession sqlSession = factory.openSession();
        //3. 获取BrandMapper
        BrandMapper mapper = sqlSession.getMapper(BrandMapper.class);

        mapper.deleteById(id);

        sqlSession.commit();
        sqlSession.close();
    }

}

private  BrandService service = new BrandService();

@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {


    //1. 调用BrandService完成查询
    List<Brand> brands = service.selectAll();

    //2. 存入request域中
    request.setAttribute("brands",brands);

    //3. 转发到brand.jsp
    request.getRequestDispatcher("/brand.jsp").forward(request,response);
}
通过id查询：

//1. 接收id
String id = request.getParameter("id");
//2. 调用service查询
Brand brand = service.selectById(Integer.parseInt(id));
//3. 存储到request中
request.setAttribute("brand",brand);

//4. 转发到update.jsp
request.getRequestDispatcher("/update.jsp").forward(request,response);
增加：

 //处理POST请求的乱码问题

    request.setCharacterEncoding("utf-8");

    //1. 接收表单提交的数据，封装为一个Brand对象
    String brandName = request.getParameter("brandName");
    String companyName = request.getParameter("companyName");
    String ordered = request.getParameter("ordered");
    String description = request.getParameter("description");
    String status = request.getParameter("status");
    //封装为一个Brand对象
    Brand brand = new Brand();
    brand.setBrandName(brandName);
    brand.setCompanyName(companyName);
    brand.setOrdered(Integer.parseInt(ordered));
    brand.setDescription(description);
    brand.setStatus(Integer.parseInt(status));
    //2. 调用service 完成添加
    service.add(brand);
    //3. 转发到查询所有Servlet
    request.getRequestDispatcher("/selectAllServlet").forward(request,response);
}

修改：

   //处理POST请求的乱码问题
    request.setCharacterEncoding("utf-8");

    //1. 接收表单提交的数据，封装为一个Brand对象
    String id = request.getParameter("id");
    String brandName = request.getParameter("brandName");
    String companyName = request.getParameter("companyName");
    String ordered = request.getParameter("ordered");
    String description = request.getParameter("description");
    String status = request.getParameter("status");

    //封装为一个Brand对象
    Brand brand = new Brand();
    brand.setId(Integer.parseInt(id));
    brand.setBrandName(brandName);
    brand.setCompanyName(companyName);
    brand.setOrdered(Integer.parseInt(ordered));
    brand.setDescription(description);
    brand.setStatus(Integer.parseInt(status));


    //2. 调用service 完成修改
    service.update(brand);


    //3. 转发到查询所有Servlet
    request.getRequestDispatcher("/selectAllServlet").forward(request,response);
}通过id删除：

   //1. 接收id
    String id = req.getParameter("id");
    //2. 调用service查询
     service.deleteById(Integer.parseInt(id));
    //3. 存储到request中


    //3. 转发到查询所有Servlet
    req.getRequestDispatcher("/selectAllServlet").forward(req,resp);

}