2024/1/15日 日志 关于Vue && Element 的后续---》综合案例（3）

功能1：查询所有

ResultMap准备：

点击查看代码

    <resultMap id="brandResultMap" type="brand">
        <result property="brandName" column="brand_name" />
        <result property="companyName" column="company_name" />
    </resultMap>

BrandMapper

点击查看代码

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

impl内创建BrandServiceImpl，此举是为了方便以后若Service层发生更改，Servlet层无需再次更改

BrandServiceImpl

点击查看代码

   //1. 创建SqlSessionFactory 工厂对象
    SqlSessionFactory factory = SqlSessionFactoryUtils.getSqlSessionFactory();    

@Override
    public List<Brand> selectAll() {
        //2. 获取SqlSession对象
        SqlSession sqlSession = factory.openSession();
        //3. 获取BrandMapper
        BrandMapper mapper = sqlSession.getMapper(BrandMapper.class);

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

        //5. 释放资源
        sqlSession.close();

        return brands;
    }

BrandService

点击查看代码

    /**
     * 查询所有
     * @return
     */
    List<Brand> selectAll();

SelectAllServlet

点击查看代码

package com.Moonbeams.web.servlet.old;

import com.Moonbeams.pojo.Brand;
import com.Moonbeams.service.BrandService;
import com.Moonbeams.service.impl.BrandServiceImpl;
import com.alibaba.fastjson.JSON;

import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
import java.io.IOException;
import java.util.List;

//@WebServlet("/selectAllServlet")
public class SelectAllServlet extends HttpServlet {

    private BrandService brandService = new BrandServiceImpl();

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //1. 调用service查询
        List<Brand> brands = brandService.selectAll();

        //2. 转为JSON
        String jsonString = JSON.toJSONString(brands);

        //3. 写数据
        response.setContentType("text/json;charset=utf-8");
        response.getWriter().write(jsonString);
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doGet(request, response);
    }
}