4. 业务代码

 4.1 持久层

        根据需求, 先⼤致计算有哪些DB相关操作, 完成持久层初步代码, 后续再根据业务需求进⾏完善

        1. ⽤⼾登录⻚

                a. 根据⽤⼾名查询⽤⼾信息

        2. 博客列表⻚

                a. 根据id查询user信息

                b. 获取所有博客列表

        3. 博客详情⻚

                a. 根据博客ID查询博客信息

                b. 根据博客ID删除博客(修改delete_flag=1)

        4. 博客修改⻚

                a. 根据博客ID修改博客信息

        5. 发表博客

                a. 插⼊新的博客数据

        根据以上分析, 来实现持久层的代码：

package com.example.spring_blog_24_9_8.mapper;

import com.example.spring_blog_24_9_8.model.Blog;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Select;

import java.util.List;
@Mapper
public interface BlogMapper {

    @Select("Select id,title,content,user_id,delete_flag,create_time,update_time" +
            "from blog where delete_flag = 0 order by create_time desc")
    List<Blog> selectAllBlogs();


    @Insert("insert into blog (title,content,user_id) values (#{title},#{content},#{userId})")
    int insertBlog(Blog record);

    @Select("select * from blog where id = #{id}")
    Blog selectById(Integer id);

    int updateBlog(Blog blog);

}

package com.example.spring_blog_24_9_8.mapper;

import com.example.spring_blog_24_9_8.model.User;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Select;
@Mapper
public interface UserMapper {

    @Select("select id, user_name, password, github_url, delete_flag, create_time " +
            "from user where id = #{id}")
    User selectById(Integer id);

    @Select("select id, user_name, password, github_url, delete_flag, create_time " +
                "from user where user_name = #{userName}")
    User selectByName(String name);

}

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.example.spring_blog_24_9_8.mapper.BlogMapper">
    <update id="updateBlog">
        update blog
        <set>
            <if test="title!=null">
                title = #{title},
            </if>
            <if test="content!=null">
                content = #{content},
            </if>
            <if test="deleteFlag!=null">
                delete_flag = #{deleteFlag},
            </if>
        </set>
        where id = #{id}
    </update>
</mapper>

书写测试⽤例, 简单进⾏单元测试 

package com.example.spring_blog_24_9_8.mapper;

import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

import static org.junit.jupiter.api.Assertions.*;
@SpringBootTest
class UserMapperTest {

    @Autowired
    private UserMapper userMapper;

    @Test
    void selectById() {
        System.out.println(userMapper.selectById(2));
    }

    @Test
    void selectByName() {
        System.out.println(userMapper.selectByName("shenmengyao"));

    }
}

selectbyid结果如下：

selestbyname结果如下：

package com.example.spring_blog_24_9_8.mapper;

import com.example.spring_blog_24_9_8.model.Blog;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

import static org.junit.jupiter.api.Assertions.*;
@SpringBootTest
class BlogMapperTest {

    @Autowired
    private BlogMapper blogMapper;


    @Test
    void selectAllBlogs() {
        System.out.println(blogMapper.selectAllBlogs());
    }

    @Test
    void insertBlog() {
        Blog blog = new Blog();
        blog.setTitle("测试接⼝");
        blog.setContent("单元测试测试接⼝测试接⼝");
        blog.setUserId(1);
        blogMapper.insertBlog(blog);
    }

    @Test
    void selectById() {
        System.out.println(blogMapper.selectById(3));
    }

    @Test
    void updateBlog() {
        Blog blog = new Blog();
        blog.setId(3);
        blog.setDeleteFlag(1);
        blog.setTitle("测试修改接⼝");
        blog.setContent("测试修改接⼝测试修改接⼝测试修改接⼝");
        blogMapper.updateBlog(blog);
    }
}

selectallblogs结果如下：

insertblog结果如下：

 selectbyid结果如下：

updateblog结果如下：

4.2 实现博客列表

4.2.1 约定前后端交互接⼝ 

[请求]
/blog/getlist
[响应]
{
 "code": 200,
 "msg": "",
 "data": [{
 "id": 1,
 "title": "第⼀篇博客",
 "content": "111我是博客正⽂我是博客正⽂我是博客正⽂",
 "userId": 1,
 "deleteFlag": 0,
 "createTime": "2023-10-21 16:56:57",
 "updateTime": "2023-10-21T08:56:57.000+00:00"
 },
 .....
 ]
}

        客⼾端给服务器发送⼀个 /blog/getlist 这样的 HTTP 请求, 服务器给客户端返回了⼀个 JSON 格 式的数据.

4.2.2 实现服务器代码

控制层代码：

@RestController
@RequestMapping("/blog")
public class BlogController {
    @Autowired
    private BlogService blogService;

    @RequestMapping("/getList")
    public List<Blog> getList(){
        return blogService.getBlogList();
    }
}

服务层代码 ：

@Service
public class BlogService {
    @Autowired
    private BlogMapper blogMapper;

    public List<Blog> getBlogList(){
        return blogMapper.selectAllBlogs();
    }
}

运行程序，浏览器访问http://127.0.0.1:8087/blog/getList，结果如下：