基于SpringBoot + Vue的个人博客系统02——简单的CRUD

曾经终败给现在 2022-12-02 01:00 212阅读 0赞

## 简介 ##

数据库使用 MySQL 、持久层框架使用 Mybatis-plus，本篇文章介绍对文章表简单的增删改查。

接口遵循 RESTful 规范，详情可参考：[理解RESTful架构——阮一峰][RESTful]

## 代码实现 ##

1、首先导入依赖

<dependency>
        <groupId>com.baomidou</groupId>
        <artifactId>mybatis-plus-boot-starter</artifactId>
        <version>3.3.2</version>
    </dependency>
    
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>8.0.18</version>
    </dependency>

> Mybatis-plus 官网：https://mp.baomidou.com

2、配置数据源，以及 dao 层日志级别

> application-dev.yml

spring:
      datasource:
        driver-class-name: com.mysql.cj.jdbc.Driver
        url: jdbc:mysql://localhost:3306/blog?serverTimezone=UTC&useUnicode=true&characterEncoding=utf8&useSSL=false
        username: root
        password: 111111
    logging:
      level:
        pers.qianyucc.qblog.dao: trace

3、新建文章表

CREATE TABLE `articles` (
      `id` varchar(30) NOT NULL,
      `author` varchar(20) NOT NULL,
      `category` varchar(50) DEFAULT NULL,
      `tabloid` varchar(255) DEFAULT NULL,
      `content` text,
      `tags` varchar(50) DEFAULT NULL,
      `title` varchar(100) DEFAULT NULL,
      `type` int(11) DEFAULT NULL,
      `views` int(11) DEFAULT NULL,
      `gmt_create` bigint(20) DEFAULT NULL,
      `gmt_update` bigint(20) DEFAULT NULL,
      PRIMARY KEY (`id`) USING BTREE
    ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;

4、新建对应的实体类

package pers.qianyucc.qblog.model.entity;
    
    import com.baomidou.mybatisplus.annotation.*;
    import lombok.*;
    
    import java.io.*;
    
    @Data
    @TableName("articles")
    public class ArticlePO implements Serializable { 
        private static final long serialVersionUID = -1849698844197610571L;
        @TableId
        private String id;
        private String author;
        private String title;
        private String content;
        private String tags;
        private Integer type;
        private String category;
        private Long gmtCreate;
        private Long gmtUpdate;
        private String tabloid;
        private Integer views;
    }

说明：

*  @TableName：手动指定表名，如果表名和实体类名相同的话可以不加
 *  @TableId：表示这个属性对应的是数据库中表的主键

5、新建 dao 层接口

package pers.qianyucc.qblog.dao;
    
    import com.baomidou.mybatisplus.core.mapper.*;
    import pers.qianyucc.qblog.model.entity.*;
    
    @Mapper
    public interface ArticleMapper extends BaseMapper<ArticlePO> { 
    }

说明：

*  Mybatis-plus 的使用方法和 Spring Data Jpa 类似，都是 dao层的接口继承了一个特定接口之后就有了对数据表操作的基本功能

6、配置分页，注意加上注解扫描

package pers.qianyucc.qblog.config;
    
    import com.baomidou.mybatisplus.extension.plugins.*;
    import com.baomidou.mybatisplus.extension.plugins.pagination.optimize.*;
    import org.mybatis.spring.annotation.*;
    import org.springframework.context.annotation.*;
    import org.springframework.transaction.annotation.*;
    
    @EnableTransactionManagement
    @Configuration
    @MapperScan("pers.qianyucc.qblog.dao")
    public class MybatisPlusConfig { 
        @Bean
        public PaginationInterceptor paginationInterceptor() { 
            PaginationInterceptor paginationInterceptor = new PaginationInterceptor();
            // 设置请求的页面大于最大页后操作， true调回到首页，false 继续请求 默认false
            paginationInterceptor.setOverflow(false);
            // 设置最大单页限制数量，默认 500 条，-1 不受限制
            paginationInterceptor.setLimit(10);
            // 开启 count 的 join 优化,只针对部分 left join
            paginationInterceptor.setCountSqlParser(new JsqlParserCountOptimize(true));
            return paginationInterceptor;
        }
    }

7、创建 VO 转换接口，用于由 PO 转换成 VO

package pers.qianyucc.qblog.model.vo;
    
    public interface IConverter<T,E> { 
        /** * VO 转换函数 * * @param t 目标对象 * @return 转换结果 */
        E convertToVO(T t);
    }

说明：

*  对于 PO 向 VO 的转化，我们可以直接在业务层使用他们的 set、get方法，但是这样的话代码可读性就会变差，常常会在业务层出现一大堆与业务无关的代码，这就是封装 PO 到 VO 转换器的理由。

8、创建 ArticleVO 类，并实现 PO 到 VO 转换的方法

package pers.qianyucc.qblog.model.vo;
    
    import cn.hutool.core.bean.*;
    import cn.hutool.core.bean.copier.*;
    import lombok.*;
    import pers.qianyucc.qblog.model.entity.*;
    import pers.qianyucc.qblog.model.enums.*;
    import pers.qianyucc.qblog.utils.*;
    
    @Data
    public class ArticleVO { 
        private String id;
        private String author;
        private String title;
        private String content;
        private String[] tags;
        private String type;
        private String category;
        private String gmtCreate;
        private String gmtUpdate;
        private String tabloid;
        private Integer views;
    
        /** * 根据 PO 创建 VO 对象 * @param articlePO PO对象 * @return VO对象 */
        public static ArticleVO fromArticlePO(ArticlePO articlePO) { 
            return new Converter().convertToVO(articlePO);
        }
    
        private static class Converter implements IConverter<ArticlePO, ArticleVO> { 
            @Override
            public ArticleVO convertToVO(ArticlePO article) { 
                final ArticleVO vo = new ArticleVO();
                BeanUtil.copyProperties(article, vo, CopyOptions.create()
                        .ignoreNullValue().ignoreError());
                vo.setTags(article.getTags().split(","));
                for (ArticleTypeEnum item : ArticleTypeEnum.values()) { 
                    if (item.getFlag() == article.getType()) { 
                        vo.setType(item.getNotes());
                    }
                }
                vo.setGmtCreate(BlogUtils.formatDatetime(article.getGmtCreate()));
                vo.setGmtUpdate(BlogUtils.formatDatetime(article.getGmtUpdate()));
                return vo;
            }
        }
    }

这里的文章类型为一个枚举类型

package pers.qianyucc.qblog.model.enums;
    
    public enum ArticleTypeEnum { 
        /** * 文章类型：原创 */
        ORIGINAL("原创", 1),
        /** * 文章类型：转载 */
        REPRINT("转载", 0);;
        private String notes;
        private int flag;
    
        public String getNotes() { 
            return notes;
        }
    
        public int getFlag() { 
            return flag;
        }
    
        ArticleTypeEnum(String notes, int flag) { 
            this.notes = notes;
            this.flag = flag;
        }
    }

9、定义 PageVO 来储存分页信息

package pers.qianyucc.qblog.model.vo;
    
    import lombok.*;
    
    import java.util.*;
    
    @Data
    @Builder
    public class PageVO<T> { 
        protected List<T> records;
        protected long total;
        protected long size;
        protected long current;
    }

10、编写 ArticleService

package pers.qianyucc.qblog.service;
    
    import com.baomidou.mybatisplus.extension.plugins.pagination.*;
    import org.springframework.beans.factory.annotation.*;
    import org.springframework.stereotype.*;
    import pers.qianyucc.qblog.dao.*;
    import pers.qianyucc.qblog.model.entity.*;
    import pers.qianyucc.qblog.model.vo.*;
    
    import java.util.*;
    import java.util.stream.*;
    
    @Service
    public class ArticleService { 
        @Autowired
        private ArticleMapper articleMapper;
    
        public PageVO<ArticleVO> getArticles(int page, int limit) { 
            QueryWrapper<ArticlePO> qw = new QueryWrapper<>();
            qw.select(ArticlePO.class, i -> !"content".equals(i.getColumn()));
            Page<ArticlePO> res = articleMapper.selectPage(new Page<>(page, limit), qw);
            List<ArticleVO> articleVOS = res.getRecords().stream()
                    .map(ArticleVO::fromArticlePO)
                    .collect(Collectors.toList());
            PageVO<ArticleVO> pageVO = PageVO.<ArticleVO>builder()
                    .records(articleVOS.isEmpty() ? new ArrayList<>() : articleVOS)
                    .total(res.getTotal())
                    .current(res.getCurrent())
                    .size(res.getSize())
                    .build();
            return pageVO;
        }
    }

说明：

*  因为我们分页查询的时候，通常不需要文章内容，所以这里使用 QueryWrapper 的 select 方法，过滤了 content 字段。

11、编写 ArticleController

package pers.qianyucc.qblog.controller;
    
    import io.swagger.annotations.*;
    import org.springframework.beans.factory.annotation.*;
    import org.springframework.web.bind.annotation.*;
    import pers.qianyucc.qblog.model.vo.*;
    import pers.qianyucc.qblog.service.*;
    
    @Api("与文章相关的api接口")
    @RestController
    public class ArticleController { 
        @Autowired
        private ArticleService articleService;
    
        @ApiOperation("批量获取文章")
        @GetMapping("/articles")
        public Results<PageVO> getArticles(
                @ApiParam("页码")
                @RequestParam(required = false, defaultValue = "1") Integer page,
                @ApiParam("每页存放的记录数")
                @RequestParam(required = false, defaultValue = "5") Integer limit) { 
            return Results.ok(articleService.getArticles(page, limit));
        }
    }

12、启动项目，访问`http://localhost:9000/api/v1/doc.html`，使用 Swagger 测试接口

![分页查询测试][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2xpMzQ1NTI3NzkyNQ_size_16_color_FFFFFF_t_70_pic_center]

### 插入 ###

1、新建 ArticleDTO 封装从前端获取到的数据

package pers.qianyucc.qblog.model.dto;
    
    import cn.hutool.core.bean.*;
    import io.swagger.annotations.*;
    import lombok.*;
    import org.hibernate.validator.constraints.*;
    import pers.qianyucc.qblog.model.entity.*;
    
    import javax.validation.constraints.NotEmpty;
    
    @Data
    @ApiModel(value = "文章类", description = "前端传入的文章信息")
    public class ArticleDTO { 
        @NotEmpty(message = "文章作者不能为空")
        @ApiModelProperty(notes = "文章作者", example = "竹林笔墨")
        private String author;
        @NotEmpty(message = "文章标题不能为空")
        @ApiModelProperty(notes = "文章标题", example = "快速入门SpringBoot")
        private String title;
        @NotEmpty(message = "文章内容不能为空")
        @ApiModelProperty(notes = "文章内容")
        private String content;
        @NotEmpty(message = "文章标签不能为空")
        @ApiModelProperty(notes = "文章标签，用英文逗号隔开", example = "java,集合")
        private String tags;
        @Range(min = 0, max = 1, message = "文章类型必须为1或者0")
        @ApiModelProperty(notes = "文章类型，0表示转载，1表示原创", example = "1")
        private Integer type;
        @NotEmpty(message = "文章分类不能为空")
        @ApiModelProperty(notes = "文章分类", example = "设计模式")
        private String category;
        @NotEmpty(message = "文章简介不能为空")
        @ApiModelProperty(notes = "文章摘要")
        private String tabloid;
    
        /** * 将 DTO 转换为 PO * * @param articleDTO 要转换的DTO * @param isUpdate 此对象是否为更新对象 * @return 转换结果 */
        public ArticlePO toArticlePO(boolean isUpdate) { 
            ArticlePO po = new Converter().convertToPO(this);
            po.setViews(isUpdate ? null : 0);
            po.setGmtCreate(isUpdate ? null : po.getGmtUpdate());
            return po;
        }
    
        private static class Converter implements IConverter<ArticleDTO, ArticlePO> { 
            @Override
            public ArticlePO convertToPO(ArticleDTO articleDTO) { 
                ArticlePO po = new ArticlePO();
                po.setGmtUpdate(System.currentTimeMillis());
                BeanUtil.copyProperties(articleDTO, po);
                return po;
            }
        }
    }

说明：

*  ApiModel、ApiModelProperty 为 Swagger 注解，用于描述该实体类
 *  NotEmpty、Range 注解可以实现参数校验，详情可以参考：[如何在 Spring/Spring Boot 中做参数校验？你需要了解的都在这里！][Spring_Spring Boot]
 *  DTO 转 PO 的转换接口如下

package pers.qianyucc.qblog.model.dto;
    
    public interface IConverter<T,E> { 
        /** * 将对应的 DTO 转换为 PO * @param t 需要转换的 DTO 类 * @return 转换结果 */
        E convertToPO(T t);
    }

2、ArticleConreoller

@PostMapping("/articles")
    @ApiOperation("新增文章")
    public Results postArticles(@ApiParam(name = "文章信息", value = "传入json格式", required = true)
                                @RequestBody @Valid ArticleDTO articleDTO) { 
        String id = articleService.insArticle(articleDTO);
        return Results.ok(MapUtil.of("id", id));
    }

说明：

*  @Valid：用于校验参数，校验失败的话就会抛出 MethodArgumentNotValidException 异常
 *  MapUtil.of：为Hutool工具包中工具类，可以快速构建一个键值对的Map

3、ArticleService

public String insArticle(ArticleDTO articleDTO) { 
        ArticlePO po = articleDTO.toArticlePO(false);
        String id = IdUtil.objectId();
        po.setId(id);
        articleMapper.insert(po);
        return id;
    }

说明：

*  IdUtil 为 Hutool 工具类中一个id生成工具，这里的 ObjectId 是 MongoDB 数据库的一种唯一ID生成策略，是UUID version1的变种

4、别忘了全局异常处理（处理参数校验失败异常）

> GlobalExceptionHandler

@ResponseBody
    @ExceptionHandler(MethodArgumentNotValidException.class)
    @ResponseStatus(HttpStatus.OK)
    public Results handleValidationExceptions(MethodArgumentNotValidException e) { 
        Map<String, String> errors = new HashMap<>();
        e.getBindingResult().getAllErrors().forEach((error) -> { 
            String fieldName = ((FieldError) error).getField();
            String errorMessage = error.getDefaultMessage();
            errors.put(fieldName, errorMessage);
        });
        return Results.error("参数错误", errors);
    }

5、使用 Swagger 测试

![测试插入][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2xpMzQ1NTI3NzkyNQ_size_16_color_FFFFFF_t_70_pic_center 1]

当某一字段为空时：

![插入时字段空白异常][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2xpMzQ1NTI3NzkyNQ_size_16_color_FFFFFF_t_70_pic_center 2]

### 根据 id 获取文章 ###

1、ArticleController

@GetMapping("/article/{id}")
    @ApiOperation("根据id查询文章信息")
    @ApiImplicitParam(name = "id", value = "文章id", required = true, dataType = "String", paramType = "path")
    public Results<ArticleVO> getArticle(@PathVariable String id) { 
        ArticleVO articleVO = articleService.findById(id);
        return Results.ok(articleVO);
    }

2、ArticleService

public ArticleVO findById(String id) { 
        ArticlePO articlePO = articleMapper.selectById(id);
        if (Objects.isNull(articlePO)) { 
            throw new BlogException(INVALID_ID);
        }
        return ArticleVO.fromArticlePO(articlePO);
    }

说明：

*  其中`INVALID_ID`在`ErrorInfoEnum`中定义：`INVALID_ID(4008, "你的id不合法"),`

使用 Swagger 测试

![获取图片测试][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2xpMzQ1NTI3NzkyNQ_size_16_color_FFFFFF_t_70_pic_center 3]

### 删除文章 ###

1、ArticleController

@DeleteMapping("/article/{id}")
    @ApiOperation("根据id删除文章")
    @ApiImplicitParam(name = "id", value = "文章id", required = true, dataType = "String", paramType = "path")
    public Results deleteArticle(@PathVariable String id) { 
        articleService.deleteArticle(id);
        return Results.ok("删除成功", null);
    }

2、ArticleService

public void deleteArticle(String id) { 
        int i = articleMapper.deleteById(id);
        if (i <= 0) { 
            throw new BlogException(INVALID_ID);
        }
    }

使用 Swagger 测试

![删除文章测试][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2xpMzQ1NTI3NzkyNQ_size_16_color_FFFFFF_t_70_pic_center 4]

再次查询文章，发现文章已经不存在

![再次访问，文章已不存在][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2xpMzQ1NTI3NzkyNQ_size_16_color_FFFFFF_t_70_pic_center 5]

### 修改文章 ###

1、ArticleController 注意这里不使用 `@Valid` 注解，因为我们不一定总是需要更新全部字段

@PutMapping("/article/{id}")
    @ApiOperation("修改文章")
    @ApiImplicitParam(name = "id", value = "文章id", required = true, dataType = "String", paramType = "path")
    public Results<Map<String, Object>> putArticles(@ApiParam(name = "要修改的文章信息", value = "传入json格式", required = true)
                                                    @RequestBody ArticleDTO articleDTO,
                                                    @PathVariable String id) { 
        articleService.updateArticle(articleDTO, id);
        return Results.ok("更新成功", MapUtil.of("id", id));

2、ArticleService

public void updateArticle(ArticleDTO articleDTO, String id) { 
        ArticlePO dbArticle = articleMapper.selectById(id);
        if (Objects.isNull(dbArticle)) { 
            throw new BlogException(INVALID_ID);
        }
        ArticlePO articlePO = articleDTO.toArticlePO(true);
        articlePO.setId(id);
        articleMapper.updateById(articlePO);
    }

先查询文章信息

![查询文章信息][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2xpMzQ1NTI3NzkyNQ_size_16_color_FFFFFF_t_70_pic_center 6]

更新文章内容

![更新文章内容][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2xpMzQ1NTI3NzkyNQ_size_16_color_FFFFFF_t_70_pic_center 7]

再次查询，发现文章内容已经修改

![再次查询文章][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2xpMzQ1NTI3NzkyNQ_size_16_color_FFFFFF_t_70_pic_center 8]

参考代码：https://gitee.com/qianyucc/QBlog2/tree/v-2.0

[RESTful]: http://www.ruanyifeng.com/blog/2011/09/restful.html
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[Spring_Spring Boot]: https://github.com/Snailclimb/springboot-guide/blob/master/docs/advanced/spring-bean-validation.md
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