Mybatis中对象传参及@RequestBody,@Param使用

柔情只为你懂 2024-03-31 17:19 60阅读 0赞

简介：本文基于博客实体类，对在SpringBoot框架下前端传给后端参数为对象类型时的具体使用做了介绍。

提示：建议一定要仔细看红色注意部分。

## SpringBoot层级运行流程基础知识介绍： ##

1.  控制层接收前端请求，调用对应的业务层接口方法
2.  业务层实现类去实现业务层接口
3.  业务层实现类的方法内调用数据层的接口
4.  数据层实现文件（mapper.xml）实现数据层接口
5.  然后处理结果层层返回

下面给出了controller，mapper，mapper.xml，entity中的代码。

## SpringBoot层级代码： ##

### controller： ###

@GetMapping("/test")
    	public R<Blog> test(@Valid @RequestBody Blog blog){
    		Blog detail = service.test(blog);
    		return R.data(detail);
    	}

#### 注： ####

1.  @Valid 注解修饰Blog参数，用于判断传入Blog是否符合规则；具体细节参考：[@Valid用法详解![icon-default.png?t=M85B][icon-default.png_t_M85B]https://blog.csdn.net/weixin\_43587472/article/details/110388778?ops\_request\_misc=%257B%2522request%255Fid%2522%253A%2522167083157016782412549293%2522%252C%2522scm%2522%253A%252220140713.130102334..%2522%257D&request\_id=167083157016782412549293&biz\_id=0&utm\_medium=distribute.pc\_search\_result.none-task-blog-2~all~top\_positive~default-1-110388778-null-null.142^v68^pc\_rank\_34\_queryrelevant25,201^v4^add\_ask,213^v2^t3\_esquery\_v1&utm\_term=%40Valid&spm=1018.2226.3001.4187][Valid_icon-default.png_t_M85B_icon-default.png_t_M85B_https_blog.csdn.net_weixin_43587472_article_details_110388778_ops_request_misc_257B_2522request_255Fid_2522_253A_2522167083157016782412549293_2522_252C_2522scm_2522_253A_252220140713.130102334.._2522_257D_request_id_167083157016782412549293_biz_id_0_utm_medium_distribute.pc_search_result.none-task-blog-2_all_top_positive_default-1-110388778-null-null.142_v68_pc_rank_34_queryrelevant25_201_v4_add_ask_213_v2_t3_esquery_v1_utm_term_40Valid_spm_1018.2226.3001.4187]
2.  @RequestBody注解修饰Blog参数，表示前端传入controller层参数是JSON格式的字符串形式，具体细节参考：[@RequestBody的使用![icon-default.png?t=M85B][icon-default.png_t_M85B]https://blog.csdn.net/justry\_deng/article/details/80972817?ops\_request\_misc=%257B%2522request%255Fid%2522%253A%2522167082860916782429790905%2522%252C%2522scm%2522%253A%252220140713.130102334..%2522%257D&request\_id=167082860916782429790905&biz\_id=0&utm\_medium=distribute.pc\_search\_result.none-task-blog-2~all~top\_positive~default-1-80972817-null-null.142^v68^pc\_rank\_34\_queryrelevant25,201^v4^add\_ask,213^v2^t3\_esquery\_v1&utm\_term=%40RequestBody&spm=1018.2226.3001.4187][RequestBody_icon-default.png_t_M85B_icon-default.png_t_M85B_https_blog.csdn.net_justry_deng_article_details_80972817_ops_request_misc_257B_2522request_255Fid_2522_253A_2522167082860916782429790905_2522_252C_2522scm_2522_253A_252220140713.130102334.._2522_257D_request_id_167082860916782429790905_biz_id_0_utm_medium_distribute.pc_search_result.none-task-blog-2_all_top_positive_default-1-80972817-null-null.142_v68_pc_rank_34_queryrelevant25_201_v4_add_ask_213_v2_t3_esquery_v1_utm_term_40RequestBody_spm_1018.2226.3001.4187]

### BlogMapper： ###

public interface BlogMapper extends BaseMapper<Blog> {
    
    	Blog getInfo(@Param("blog") Blog blog);
    }

#### 注： ####

1.  在mapper文件中需要在getInfo方法的参数声明中加入@Param注解，这点很重要，如果不加@Param注解，但在mapper.xml中的sql语句中用到了传入的实体类中的属性参数，就会出现找不到属性字段的错误。
2.  @Param注解一定要是：package org.apache.ibatis.annotations下的注解，在使用idea代码自动提示补全功能时一定要注意，因为同一个注解在不同package中的功能是不同的，不要因为用错包导致程序出错；如果注解用错，导致的bug是很难排查的，在后期检测中会耗费掉大量时间。

### BlogMapper.xml： ###

<select id="test" resultType="com.fjz.screendata.entity.Blog">
            select * from blog 
            where is_deleted = 0 and id = #{blog.id}
     </select>

#### 注： ####

1.  此时blog作为传入对象，可以用对象中属性的访问方式去获取blog的id，即blog.id。
2.  如果在xml中书写blog.id时有自动补全的提示，说明@Param注解已经在blog上生效了。

### entity： ###

public class Blog {
    	private static final long serialVersionUID = 1L;
    
    	/**
    	 * 博客id
    	 */
    	private String remark;
    
    	/**
    	 * 备注信息
    	 */
    	private String remark;
    
    }

### postman测试： ###

![54c14fc4a3fb4b67b54e751d12553a0c.png][]

注：

此时blog实体用body以JSON形式传入，postman传参细节参考：

[postman中params传参与body传参区别![icon-default.png?t=M85B][icon-default.png_t_M85B]https://blog.csdn.net/weixin\_44575911/article/details/111148852][postman_params_body_icon-default.png_t_M85B_icon-default.png_t_M85B_https_blog.csdn.net_weixin_44575911_article_details_111148852]

[icon-default.png_t_M85B]: https://csdnimg.cn/release/blog_editor_html/release2.2.0/ckeditor/plugins/CsdnLink/icons/icon-default.png?t=M85B
[Valid_icon-default.png_t_M85B_icon-default.png_t_M85B_https_blog.csdn.net_weixin_43587472_article_details_110388778_ops_request_misc_257B_2522request_255Fid_2522_253A_2522167083157016782412549293_2522_252C_2522scm_2522_253A_252220140713.130102334.._2522_257D_request_id_167083157016782412549293_biz_id_0_utm_medium_distribute.pc_search_result.none-task-blog-2_all_top_positive_default-1-110388778-null-null.142_v68_pc_rank_34_queryrelevant25_201_v4_add_ask_213_v2_t3_esquery_v1_utm_term_40Valid_spm_1018.2226.3001.4187]: https://blog.csdn.net/weixin_43587472/article/details/110388778?ops_request_misc=%257B%2522request%255Fid%2522%253A%2522167083157016782412549293%2522%252C%2522scm%2522%253A%252220140713.130102334..%2522%257D&request_id=167083157016782412549293&biz_id=0&utm_medium=distribute.pc_search_result.none-task-blog-2~all~top_positive~default-1-110388778-null-null.142%5Ev68%5Epc_rank_34_queryrelevant25,201%5Ev4%5Eadd_ask,213%5Ev2%5Et3_esquery_v1&utm_term=%40Valid&spm=1018.2226.3001.4187
[RequestBody_icon-default.png_t_M85B_icon-default.png_t_M85B_https_blog.csdn.net_justry_deng_article_details_80972817_ops_request_misc_257B_2522request_255Fid_2522_253A_2522167082860916782429790905_2522_252C_2522scm_2522_253A_252220140713.130102334.._2522_257D_request_id_167082860916782429790905_biz_id_0_utm_medium_distribute.pc_search_result.none-task-blog-2_all_top_positive_default-1-80972817-null-null.142_v68_pc_rank_34_queryrelevant25_201_v4_add_ask_213_v2_t3_esquery_v1_utm_term_40RequestBody_spm_1018.2226.3001.4187]: https://blog.csdn.net/justry_deng/article/details/80972817?ops_request_misc=%257B%2522request%255Fid%2522%253A%2522167082860916782429790905%2522%252C%2522scm%2522%253A%252220140713.130102334..%2522%257D&request_id=167082860916782429790905&biz_id=0&utm_medium=distribute.pc_search_result.none-task-blog-2~all~top_positive~default-1-80972817-null-null.142%5Ev68%5Epc_rank_34_queryrelevant25,201%5Ev4%5Eadd_ask,213%5Ev2%5Et3_esquery_v1&utm_term=%40RequestBody&spm=1018.2226.3001.4187
[54c14fc4a3fb4b67b54e751d12553a0c.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/31/40e9a83ba6d2499d84dd414ca57d163f.png
[postman_params_body_icon-default.png_t_M85B_icon-default.png_t_M85B_https_blog.csdn.net_weixin_44575911_article_details_111148852]: https://blog.csdn.net/weixin_44575911/article/details/111148852