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springboot+mybatis实现简单的增、删、查、改_springbootmybatis增删改查

作者：AllinToyou | 2024-03-14 09:14:27

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springbootmybatis增删改查

这篇文章主要针对java初学者，详细介绍怎么创建一个基本的springboot项目来对数据库进行crud操作。

第一步：创建springboot项目

在IntelliJ IDEA中通过spring initilizer创建springboot项目如图，依次点击左上角的菜单栏中的File >> New >> Project...

然后在打开的窗口左侧选择Spring Initilizer，在右侧面板：

  • 修改项目名为springboot-crud
  • 修改包名为com.example.springboot
  • 修改java版本为8

然后点击Next按钮

接着点击Finish按钮，等待idea创建并下载springboot项目。

第二步：修改pom.xml

修改pom.xml配置文件，修改springboot的版本为2.5.9，并添加和必要的依赖，删除test依赖。

  1. <?xml version="1.0" encoding="UTF-8"?>
  2. <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  3.          xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
  4.     <modelVersion>4.0.0</modelVersion>
  5.  
  6.     <parent>
  7.         <groupId>org.springframework.boot</groupId>
  8.         <artifactId>spring-boot-starter-parent</artifactId>
  9.         <version>2.5.9</version>
  10.         <relativePath />
  11.     </parent>
  12.  
  13.     <groupId>com.example</groupId>
  14.     <artifactId>springboot-crud</artifactId>
  15.     <version>0.0.1-SNAPSHOT</version>
  16.     <name>springboot-crud</name>
  17.     <description>springboot+mybatis实现增删查改的入门项目</description>
  18.  
  19.     <properties>
  20.         <java.version>1.8</java.version>
  21.         <mysql.version>8.0.28</mysql.version>
  22.         <druid.version>1.1.21</druid.version>
  23.         <lombok.version>1.18.22</lombok.version>
  24.         <mybatis.version>2.2.2</mybatis.version>
  25.     </properties>
  26.  
  27.     <dependencies>
  28.         <dependency>
  29.             <groupId>org.springframework.boot</groupId>
  30.             <artifactId>spring-boot-starter-web</artifactId>
  31.         </dependency>
  32.  
  33.         <!--lombok：自动生成getter、setter工具-->
  34.         <dependency>
  35.             <groupId>org.projectlombok</groupId>
  36.             <artifactId>lombok</artifactId>
  37.             <version>${lombok.version}</version>
  38.         </dependency>
  39.  
  40.         <!--mysql驱动-->
  41.         <dependency>
  42.             <groupId>mysql</groupId>
  43.             <artifactId>mysql-connector-java</artifactId>
  44.             <version>${mysql.version}</version>
  45.         </dependency>
  46.  
  47.         <!--druid数据库连接池-->
  48.         <dependency>
  49.             <groupId>com.alibaba</groupId>
  50.             <artifactId>druid</artifactId>
  51.             <version>${druid.version}</version>
  52.         </dependency>
  53.  
  54.         <!--spring boot整合mybatis的依赖-->
  55.         <dependency>
  56.             <groupId>org.mybatis.spring.boot</groupId>
  57.             <artifactId>mybatis-spring-boot-starter</artifactId>
  58.             <version>${mybatis.version}</version>
  59.         </dependency>
  60.     </dependencies>
  61.  
  62.     <build>
  63.         <plugins>
  64.             <plugin>
  65.                 <groupId>org.springframework.boot</groupId>
  66.                 <artifactId>spring-boot-maven-plugin</artifactId>
  67.             </plugin>
  68.         </plugins>
  69.     </build>
  70. </project>

第三步：准备数据库

创建一个数据库springboot-crud，然后执行项目doc/sql目录下的springboot-crud.sql

第四步：修改配置文件

springboot的配置文件有两种格式，即application.properties或application.yml。

推荐使用yml文件格式，重命名application.properties为application.yml。然后添加数据库的数据源设置，并修改项目的启动端口号为8083，然后设置mybatis的mapper.xml文件的位置以及日志隔离级别为debug（默认info）。

  1. spring:
  2.   datasource:
  3.     username: root
  4.     password: root
  5.     url: jdbc:mysql://localhost:3306/springboot-crud
  6.     driver-class-name: com.mysql.cj.jdbc.Driver
  7.     type: com.alibaba.druid.pool.DruidDataSource
  8.  
  9. server:
  10.   port: 8083
  11.  
  12. mybatis:
  13.   mapper-locations: classpath:mapper/*Mapper.xml
  14.  
  15. logging:
  16.   level:
  17.     springfox: error
  18.     com.example.springboot: debug

第五步：创建数据库对应的实体类

在项目的根目录com.example.springboot下创建entity包，然后在entity包下面创建一个实体类Song.java，并实现序列化接口Serializable。

  1. package com.example.springboot.entity;
  2.  
  3. import com.fasterxml.jackson.annotation.JsonFormat;
  4. import lombok.Data;
  5.  
  6. import java.io.Serializable;
  7. import java.time.LocalDateTime;
  8.  
  9. /**
  10.  * 歌曲
  11.  * @author heyunlin
  12.  * @version 1.0
  13.  */
  14. @Data
  15. public class Song implements Serializable {
  16.     private static final long serialVersionUID = 18L;
  17.  
  18.     private String id;
  19.  
  20.     /**
  21.      * 歌曲名
  22.      */
  23.     private String name;
  24.  
  25.     /**
  26.      * 歌手
  27.      */
  28.     private String singer;
  29.  
  30.     /**
  31.      * 描述信息
  32.      */
  33.     private String note;
  34.  
  35.     /**
  36.      * 最后一次修改时间
  37.      */
  38.     @JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss", timezone = "GMT+8")
  39.     private LocalDateTime lastUpdateTime;
  40. }

第六步：创建持久层接口

同样的，在项目根路径下创建mapper包，在mapper包下创建一个接口SongMapper，在接口上添加Spring组件注解@Repository。

  1. package com.example.springboot.mapper;
  2.  
  3. import org.springframework.stereotype.Repository;
  4.  
  5. /**
  6.  * @author heyunlin
  7.  * @version 1.0
  8.  */
  9. @Repository
  10. public interface SongMapper {
  11.  
  12. }

第七步：创建Mapper.xml文件

在src\main\resources下创建mapper包，然后在mapper包下面创建一个xml文件SongMapper.xml。其中namespace属性的值为SongMapper接口的全限定名

  1. <?xml version="1.0" encoding="UTF-8" ?>
  2. <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
  3.  
  4. <mapper namespace="com.example.springboot.mapper.SongMapper">
  5.  
  6. </mapper>

第八步：开启mapper包扫描

因为我们的持久层接口没有使用@Mapper注解，需要通过@MapperScan来配置mapper的包路径，通常我们会在一个单独的配置类上添加@MapperScan注解。

在项目根路径下创建config包，在config包下创建MybatisConfig.java，MybatisConfig上使用@Configuration将该类声明为配置类，通过@MapperScan注解指定mapper包扫描路径。

  1. package com.example.springboot.config;
  2.  
  3. import org.mybatis.spring.annotation.MapperScan;
  4. import org.springframework.context.annotation.Configuration;
  5.  
  6. /**
  7.  * Mybatis配置文件
  8.  * @author heyunlin
  9.  * @version 1.0
  10.  */
  11. @Configuration
  12. @MapperScan(basePackages = "com.example.springboot.mapper")
  13. public class MybatisConfig {
  14.  
  15. }

第九步：创建业务层接口

在项目根路径下创建service包，在service包下创建接口SongService.java

  1. package com.example.springboot.service;
  2.  
  3. /**
  4.  * @author heyunlin
  5.  * @version 1.0
  6.  */
  7. public interface SongService {
  8.  
  9. }

然后在service包下创建impl子包，创建一个SongService接口的实现类，并在实现类上使用@Service注解。

  1. package com.example.springboot.service.impl;
  2.  
  3. import com.example.springboot.service.SongService;
  4. import org.springframework.stereotype.Service;
  5.  
  6. /**
  7.  * @author heyunlin
  8.  * @version 1.0
  9.  */
  10. @Service
  11. public class SongServiceImpl implements SongService {
  12.  
  13. }

第十步：创建控制器类 

在项目根路径下创建controller包，在controller包下创建SongController.java类。

其中，@RestController注解是一个复合注解，由两个注解@RespondBody和@Controller组成，@RespondBody表示类下面的方法的返回值会被转换为json格式的字符串返回给调用者。

  1. package com.example.springboot.controller;
  2.  
  3. import org.springframework.web.bind.annotation.RequestMapping;
  4. import org.springframework.web.bind.annotation.RestController;
  5.  
  6. /**
  7.  * @author heyunlin
  8.  * @version 1.0
  9.  */
  10. @RestController
  11. @RequestMapping(path = "/song", produces="application/json;charset=utf-8")
  12. public class SongController {
  13.     
  14. }

至此，项目所需的所有类都创建好了，项目完整目录结构如下图：

第十一步：开始开发业务功能

完成以上步骤之后，springboot项目的基本开发环境就搭建好了，接下来开始实现对歌曲表song的增删查改功能。

在此之前，需要把service层的SongService注入到SongController中，在这里使用《阿里巴巴开发规范》推荐的构造器注入方式。

  1. package com.example.springboot.controller;
  2.  
  3. import com.example.springboot.service.SongService;
  4. import org.springframework.beans.factory.annotation.Autowired;
  5. import org.springframework.web.bind.annotation.RequestMapping;
  6. import org.springframework.web.bind.annotation.RestController;
  7.  
  8. /**
  9.  * @author heyunlin
  10.  * @version 1.0
  11.  */
  12. @RestController
  13. @RequestMapping(path = "/song", produces="application/json;charset=utf-8")
  14. public class SongController {
  15.  
  16.     private final SongService songService;
  17.  
  18.     @Autowired
  19.     public SongController(SongService songService) {
  20.         this.songService = songService;
  21.     }
  22.  
  23. }

1、添加歌曲

controller层

首先，在controller层创建一个方法，取名为insert，在方法内调用service层的对应方法，为了方便同样取名为insert

  1. package com.example.springboot.controller;
  2.  
  3. import com.example.springboot.entity.Song;
  4. import com.example.springboot.service.SongService;
  5. import org.springframework.beans.factory.annotation.Autowired;
  6. import org.springframework.web.bind.annotation.RequestMapping;
  7. import org.springframework.web.bind.annotation.RequestMethod;
  8. import org.springframework.web.bind.annotation.RestController;
  9.  
  10. /**
  11.  * @author heyunlin
  12.  * @version 1.0
  13.  */
  14. @RestController
  15. @RequestMapping(path = "/song", produces="application/json;charset=utf-8")
  16. public class SongController {
  17.  
  18.     private final SongService songService;
  19.  
  20.     @Autowired
  21.     public SongController(SongService songService) {
  22.         this.songService = songService;
  23.     }
  24.  
  25.     @RequestMapping(value = "/insert", method = RequestMethod.POST)
  26.     public void insert(Song song) {
  27.         songService.insert(song);
  28.     }
  29.  
  30. }

service层（业务层）

这时候，songService.insert(song);这行代码会报错，因为我们SongService接口没有这个方法，把鼠标移到红色的地方，键盘按alt+enter（回车键），选择第一个选项，在SongService创建insert()方法。

  1. package com.example.springboot.service;
  2.  
  3. import com.example.springboot.entity.Song;
  4.  
  5. /**
  6.  * @author heyunlin
  7.  * @version 1.0
  8.  */
  9. public interface SongService {
  10.  
  11.     void insert(Song song);
  12. }

然后这时候发现SongService这个类也有红色的提示，因为SongServiceImpl实现了SongService接口，但是没有实现刚刚添加的insert()方法。

 如上图，点击红色的提示信息，会自动打开SongServiceImpl

我们把鼠标移到类上面，会提示实现方法，点击蓝色implement methods自动生成insert()方法。

  1. package com.example.springboot.service.impl;
  2.  
  3. import com.example.springboot.entity.Song;
  4. import com.example.springboot.service.SongService;
  5. import org.springframework.stereotype.Service;
  6.  
  7. /**
  8.  * @author heyunlin
  9.  * @version 1.0
  10.  */
  11. @Service
  12. public class SongServiceImpl implements SongService {
  13.  
  14.     @Override
  15.     public void insert(Song song) {
  16.         
  17.     }
  18.  
  19. }

然后，为了能操作数据库，需要注入持久层的Mapper接口SongMapper，并调用持久层接口的方法来操作数据库。

因为表song的主键是非自增的，需要手动设置，使用当前时间生成uuid作为Id字段的值。

  1. package com.example.springboot.service.impl;
  2.  
  3. import com.example.springboot.entity.Song;
  4. import com.example.springboot.mapper.SongMapper;
  5. import com.example.springboot.service.SongService;
  6. import org.springframework.beans.factory.annotation.Autowired;
  7. import org.springframework.stereotype.Service;
  8.  
  9. import java.time.LocalDateTime;
  10. import java.time.format.DateTimeFormatter;
  11.  
  12. /**
  13.  * @author heyunlin
  14.  * @version 1.0
  15.  */
  16. @Service
  17. public class SongServiceImpl implements SongService {
  18.  
  19.     private final SongMapper songMapper;
  20.  
  21.     @Autowired
  22.     public SongServiceImpl(SongMapper songMapper) {
  23.         this.songMapper = songMapper;
  24.     }
  25.  
  26.     @Override
  27.     public void insert(Song song) {
  28.         song.setId(uuid());
  29.         
  30.         songMapper.insert(song);
  31.     }
  32.  
  33.     /**
  34.      * 根据当前时间生成UUID
  35.      * @return String
  36.      */
  37.     private static String uuid() {
  38.         DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyyMMddHHmmss");
  39.         LocalDateTime localDate = LocalDateTime.now();
  40.  
  41.         return localDate.format(formatter);
  42.     }
  43.  
  44. }

mapper层（持久层）

同样的，在SongMapper接口上创建insert()方法，如果安装了mybatisx插件，也会有红色的提示，让你在SongMapper.xml上创建对应的方法。

  1. package com.example.springboot.mapper;
  2.  
  3. import com.example.springboot.entity.Song;
  4. import org.springframework.stereotype.Repository;
  5.  
  6. /**
  7.  * @author heyunlin
  8.  * @version 1.0
  9.  */
  10. @Repository
  11. public interface SongMapper {
  12.  
  13.     void insert(Song song);
  14. }

 mapper.xml中添加一个insert标签，id属性值为方法名

  1. <?xml version="1.0" encoding="UTF-8" ?>
  2. <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
  3.  
  4. <mapper namespace="com.example.springboot.mapper.SongMapper">
  5.  
  6.     <insert id="insert">
  7.         insert into song(id, name, singer, note, last_update_time)
  8.         values(#{id}, #{name}, #{singer}, #{note}, #{lastUpdateTime})
  9.     </insert>
  10. </mapper>

当然也可以在接口上使用注解来绑定SQL语句（推荐在xml文件中编写sql）

  1. package com.example.springboot.mapper;
  2.  
  3. import com.example.springboot.entity.Song;
  4. import org.apache.ibatis.annotations.Insert;
  5. import org.springframework.stereotype.Repository;
  6.  
  7. /**
  8.  * @author heyunlin
  9.  * @version 1.0
  10.  */
  11. @Repository
  12. public interface SongMapper {
  13.  
  14.     @Insert("insert into song(id, name, singer, note, last_update_time) values(#{id}, #{name}, #{singer}, #{note}, #{lastUpdateTime})")
  15.     void insert(Song song);
  16. }

注意：只能通过注解或mapper.xml其中一个方法来绑定SQL语句，否则运行项目会报错。

2、删除歌曲

同样的，依次创建controller、service和mapper层的方法，然后在controller调用service，service调用mapper。

mapper层（持久层）

  1. package com.example.springboot.mapper;
  2.  
  3. import com.example.springboot.entity.Song;
  4. import org.springframework.stereotype.Repository;
  5.  
  6. /**
  7.  * @author heyunlin
  8.  * @version 1.0
  9.  */
  10. @Repository
  11. public interface SongMapper {
  12.  
  13.     //@Insert("insert into song(id, name, singer, note, last_update_time) values(#{id}, #{name}, #{singer}, #{note}, #{lastUpdateTime})")
  14.     void insert(Song song);
  15.  
  16.     //@Delete("delete from song where id = #{id}")
  17.     void deleteById(String id);
  18. }
  1. <?xml version="1.0" encoding="UTF-8" ?>
  2. <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
  3.  
  4. <mapper namespace="com.example.springboot.mapper.SongMapper">
  5.  
  6.     <insert id="insert">
  7.         insert into song(id, name, singer, note, last_update_time)
  8.         values(#{id}, #{name}, #{singer}, #{note}, #{lastUpdateTime})
  9.     </insert>
  10.  
  11.     <delete id="deleteById">
  12.         delete from song where id = #{id}
  13.     </delete>
  14. </mapper>

service层（业务层）

SongService.java

  1. package com.example.springboot.service;
  2.  
  3. import com.example.springboot.entity.Song;
  4.  
  5. /**
  6.  * @author heyunlin
  7.  * @version 1.0
  8.  */
  9. public interface SongService {
  10.  
  11.     void insert(Song song);
  12.  
  13.     void deleteById(String id);
  14. }

 SongServiceImpl

  1. package com.example.springboot.service.impl;
  2.  
  3. import com.example.springboot.entity.Song;
  4. import com.example.springboot.mapper.SongMapper;
  5. import com.example.springboot.service.SongService;
  6. import org.springframework.beans.factory.annotation.Autowired;
  7. import org.springframework.stereotype.Service;
  8.  
  9. /**
  10.  * @author heyunlin
  11.  * @version 1.0
  12.  */
  13. @Service
  14. public class SongServiceImpl implements SongService {
  15.  
  16.     private final SongMapper songMapper;
  17.  
  18.     @Autowired
  19.     public SongServiceImpl(SongMapper songMapper) {
  20.         this.songMapper = songMapper;
  21.     }
  22.  
  23.     @Override
  24.     public void insert(Song song) {
  25.         song.setId(uuid());
  26.  
  27.         songMapper.insert(song);
  28.     }
  29.  
  30.     @Override
  31.     public void deleteById(String id) {
  32.         songMapper.deleteById(id);
  33.     }
  34.  
  35.     /**
  36.      * 根据当前时间生成UUID
  37.      * @return String
  38.      */
  39.     private static String uuid() {
  40.         DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyyMMddHHmmss");
  41.         LocalDateTime localDate = LocalDateTime.now();
  42.  
  43.         return localDate.format(formatter);
  44.     }
  45.  
  46. }

controller层

在这里使用rest风格的请求方式，通过@PathVariable注解绑定路径参数，也就是下面歌曲编号（id）对应的字符串值

请求url格式

http://localhost:8083/song/deleteById/歌曲编号

例如，这时候id获取到的值为10011

http://localhost:8083/song/deleteById/10011

  1. package com.example.springboot.controller;
  2.  
  3. import com.example.springboot.entity.Song;
  4. import com.example.springboot.service.SongService;
  5. import org.springframework.beans.factory.annotation.Autowired;
  6. import org.springframework.web.bind.annotation.PathVariable;
  7. import org.springframework.web.bind.annotation.RequestMapping;
  8. import org.springframework.web.bind.annotation.RequestMethod;
  9. import org.springframework.web.bind.annotation.RestController;
  10.  
  11. /**
  12.  * @author heyunlin
  13.  * @version 1.0
  14.  */
  15. @RestController
  16. @RequestMapping(path = "/song", produces="application/json;charset=utf-8")
  17. public class SongController {
  18.  
  19.     private final SongService songService;
  20.  
  21.     @Autowired
  22.     public SongController(SongService songService) {
  23.         this.songService = songService;
  24.     }
  25.  
  26.     @RequestMapping(value = "/insert", method = RequestMethod.POST)
  27.     public void insert(Song song) {
  28.         songService.insert(song);
  29.     }
  30.  
  31.     @RequestMapping(value = "/deleteById/{id}", method = RequestMethod.GET)
  32.     public void deleteById(@PathVariable("id") String id) {
  33.         songService.deleteById(id);
  34.     }
  35.  
  36. }

3、修改歌曲信息

mapper层（持久层）

SongMapper.java

  1. package com.example.springboot.mapper;
  2.  
  3. import com.example.springboot.entity.Song;
  4. import org.springframework.stereotype.Repository;
  5.  
  6. /**
  7.  * @author heyunlin
  8.  * @version 1.0
  9.  */
  10. @Repository
  11. public interface SongMapper {
  12.  
  13.     //@Insert("insert into song(id, name, singer, note, last_update_time) values(#{id}, #{name}, #{singer}, #{note}, #{lastUpdateTime})")
  14.     void insert(Song song);
  15.  
  16.     //@Delete("delete from song where id = #{id}")
  17.     void deleteById(String id);
  18.  
  19.     // @Update("update song set name = #{name}, singer = #{singer}, note = #{note}, last_update_time = #{lastUpdateTime} where id = #{id}")
  20.     void updateById(Song song);
  21. }

 SongMapper.xml

  1. <?xml version="1.0" encoding="UTF-8" ?>
  2. <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
  3.  
  4. <mapper namespace="com.example.springboot.mapper.SongMapper">
  5.  
  6.     <insert id="insert">
  7.         insert into song(id, name, singer, note, last_update_time)
  8.         values(#{id}, #{name}, #{singer}, #{note}, #{lastUpdateTime})
  9.     </insert>
  10.  
  11.     <delete id="deleteById">
  12.         delete from song where id = #{id}
  13.     </delete>
  14.  
  15.     <update id="updateById">
  16.         update song
  17.         set
  18.             name = #{name}, 
  19.             singer = #{singer},
  20.             note = #{note},
  21.             last_update_time = #{lastUpdateTime}
  22.         where id = #{id}
  23.     </update>
  24. </mapper>

service层（业务层）

SongService.java

  1. package com.example.springboot.service;
  2.  
  3. import com.example.springboot.entity.Song;
  4.  
  5. /**
  6.  * @author heyunlin
  7.  * @version 1.0
  8.  */
  9. public interface SongService {
  10.  
  11.     void insert(Song song);
  12.  
  13.     void deleteById(String id);
  14.  
  15.     void updateById(Song song);
  16. }

SongServiceImpl.java

  1. package com.example.springboot.service.impl;
  2.  
  3. import com.example.springboot.entity.Song;
  4. import com.example.springboot.mapper.SongMapper;
  5. import com.example.springboot.service.SongService;
  6. import org.springframework.beans.factory.annotation.Autowired;
  7. import org.springframework.stereotype.Service;
  8.  
  9. import java.time.LocalDateTime;
  10. import java.time.format.DateTimeFormatter;
  11.  
  12. /**
  13.  * @author heyunlin
  14.  * @version 1.0
  15.  */
  16. @Service
  17. public class SongServiceImpl implements SongService {
  18.  
  19.     private final SongMapper songMapper;
  20.  
  21.     @Autowired
  22.     public SongServiceImpl(SongMapper songMapper) {
  23.         this.songMapper = songMapper;
  24.     }
  25.  
  26.     @Override
  27.     public void insert(Song song) {
  28.         song.setId(uuid());
  29.  
  30.         songMapper.insert(song);
  31.     }
  32.  
  33.     @Override
  34.     public void deleteById(String id) {
  35.         songMapper.deleteById(id);
  36.     }
  37.  
  38.     @Override
  39.     public void updateById(Song song) {
  40.         song.setLastUpdateTime(LocalDateTime.now());
  41.  
  42.         songMapper.updateById(song);
  43.     }
  44.  
  45.     /**
  46.      * 根据当前时间生成UUID
  47.      * @return String
  48.      */
  49.     private static String uuid() {
  50.         DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyyMMddHHmmss");
  51.         LocalDateTime localDate = LocalDateTime.now();
  52.  
  53.         return localDate.format(formatter);
  54.     }
  55.  
  56. }

controller层

  1. package com.example.springboot.controller;
  2.  
  3. import com.example.springboot.entity.Song;
  4. import com.example.springboot.service.SongService;
  5. import org.springframework.beans.factory.annotation.Autowired;
  6. import org.springframework.web.bind.annotation.PathVariable;
  7. import org.springframework.web.bind.annotation.RequestMapping;
  8. import org.springframework.web.bind.annotation.RequestMethod;
  9. import org.springframework.web.bind.annotation.RestController;
  10.  
  11. /**
  12.  * @author heyunlin
  13.  * @version 1.0
  14.  */
  15. @RestController
  16. @RequestMapping(path = "/song", produces="application/json;charset=utf-8")
  17. public class SongController {
  18.  
  19.     private final SongService songService;
  20.  
  21.     @Autowired
  22.     public SongController(SongService songService) {
  23.         this.songService = songService;
  24.     }
  25.  
  26.     @RequestMapping(value = "/insert", method = RequestMethod.POST)
  27.     public void insert(Song song) {
  28.         songService.insert(song);
  29.     }
  30.  
  31.     @RequestMapping(value = "/deleteById/{id}", method = RequestMethod.GET)
  32.     public void deleteById(@PathVariable("id") String id) {
  33.         songService.deleteById(id);
  34.     }
  35.  
  36.     @RequestMapping(value = "/updateById", method = RequestMethod.POST)
  37.     public void updateById(Song song) {
  38.         songService.updateById(song);
  39.     }
  40.  
  41. }

4、查询歌曲详情

controller层

  1. package com.example.springboot.controller;
  2.  
  3. import com.example.springboot.entity.Song;
  4. import com.example.springboot.service.SongService;
  5. import org.springframework.beans.factory.annotation.Autowired;
  6. import org.springframework.web.bind.annotation.PathVariable;
  7. import org.springframework.web.bind.annotation.RequestMapping;
  8. import org.springframework.web.bind.annotation.RequestMethod;
  9. import org.springframework.web.bind.annotation.RestController;
  10.  
  11. /**
  12.  * @author heyunlin
  13.  * @version 1.0
  14.  */
  15. @RestController
  16. @RequestMapping(path = "/song", produces="application/json;charset=utf-8")
  17. public class SongController {
  18.  
  19.     private final SongService songService;
  20.  
  21.     @Autowired
  22.     public SongController(SongService songService) {
  23.         this.songService = songService;
  24.     }
  25.  
  26.     @RequestMapping(value = "/insert", method = RequestMethod.POST)
  27.     public void insert(Song song) {
  28.         songService.insert(song);
  29.     }
  30.  
  31.     @RequestMapping(value = "/delete/{id}", method = RequestMethod.GET)
  32.     public void delete(@PathVariable("id") String id) {
  33.         songService.delete(id);
  34.     }
  35.  
  36.     @RequestMapping(value = "/update", method = RequestMethod.POST)
  37.     public void update(Song song) {
  38.         songService.update(song);
  39.     }
  40.  
  41.     @RequestMapping(value = "/selectById/{id}", method = RequestMethod.GET)
  42.     public Song selectById(@PathVariable("id") String id) {
  43.         return songService.selectById(id);
  44.     }
  45.  
  46. }

service层（业务层）

SongService.java

  1. package com.example.springboot.service;
  2.  
  3. import com.example.springboot.entity.Song;
  4.  
  5. /**
  6.  * @author heyunlin
  7.  * @version 1.0
  8.  */
  9. public interface SongService {
  10.  
  11.     void insert(Song song);
  12.  
  13.     void deleteById(String id);
  14.  
  15.     void updateById(Song song);
  16.  
  17.     Song selectById(String id);
  18. }

SongServiceImpl.java

  1. package com.example.springboot.service.impl;
  2.  
  3. import com.example.springboot.entity.Song;
  4. import com.example.springboot.mapper.SongMapper;
  5. import com.example.springboot.service.SongService;
  6. import org.springframework.beans.factory.annotation.Autowired;
  7. import org.springframework.stereotype.Service;
  8.  
  9. import java.time.LocalDateTime;
  10. import java.time.format.DateTimeFormatter;
  11.  
  12. /**
  13.  * @author heyunlin
  14.  * @version 1.0
  15.  */
  16. @Service
  17. public class SongServiceImpl implements SongService {
  18.  
  19.     private final SongMapper songMapper;
  20.  
  21.     @Autowired
  22.     public SongServiceImpl(SongMapper songMapper) {
  23.         this.songMapper = songMapper;
  24.     }
  25.  
  26.     @Override
  27.     public void insert(Song song) {
  28.         song.setId(uuid());
  29.  
  30.         songMapper.insert(song);
  31.     }
  32.  
  33.     @Override
  34.     public void deleteById(String id) {
  35.         songMapper.deleteById(id);
  36.     }
  37.  
  38.     @Override
  39.     public void updateById(Song song) {
  40.         song.setLastUpdateTime(LocalDateTime.now());
  41.  
  42.         songMapper.updateById(song);
  43.     }
  44.  
  45.     @Override
  46.     public Song selectById(String id) {
  47.         return songMapper.selectById(id);
  48.     }
  49.  
  50.     /**
  51.      * 根据当前时间生成UUID
  52.      * @return String
  53.      */
  54.     private static String uuid() {
  55.         DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyyMMddHHmmss");
  56.         LocalDateTime localDate = LocalDateTime.now();
  57.  
  58.         return localDate.format(formatter);
  59.     }
  60.  
  61. }

mapper层（持久层）

SongMapper.java

  1. package com.example.springboot.mapper;
  2.  
  3. import com.example.springboot.entity.Song;
  4. import org.springframework.stereotype.Repository;
  5.  
  6. /**
  7.  * @author heyunlin
  8.  * @version 1.0
  9.  */
  10. @Repository
  11. public interface SongMapper {
  12.  
  13.     //@Insert("insert into song(id, name, singer, note, last_update_time) values(#{id}, #{name}, #{singer}, #{note}, #{lastUpdateTime})")
  14.     void insert(Song song);
  15.  
  16.     //@Delete("delete from song where id = #{id}")
  17.     void deleteById(String id);
  18.  
  19.     // @Update("update song set name = #{name}, singer = #{singer}, note = #{note}, last_update_time = #{lastUpdateTime} where id = #{id}")
  20.     void updateById(Song song);
  21.  
  22.     // @Select("select * from song where id = #{id})
  23.     Song selectById(String id);
  24. }

 SongMapper.xml

  1. <?xml version="1.0" encoding="UTF-8" ?>
  2. <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
  3.  
  4. <mapper namespace="com.example.springboot.mapper.SongMapper">
  5.  
  6.     <insert id="insert">
  7.         insert into song(id, name, singer, note, last_update_time)
  8.         values(#{id}, #{name}, #{singer}, #{note}, #{lastUpdateTime})
  9.     </insert>
  10.  
  11.     <delete id="deleteById">
  12.         delete from song where id = #{id}
  13.     </delete>
  14.  
  15.     <update id="updateById">
  16.         update song set name = #{name}, singer = #{singer}, note = #{note}, last_update_time = #{lastUpdateTime} where id = #{id}
  17.     </update>
  18.  
  19.     <select id="selectById" resultType="com.example.springboot.entity.Song">
  20.         select id, name, singer, note, last_update_time as lastUpdateTime from song where id = #{id}
  21.     </select>
  22. </mapper>

最后，我们简单测试一下写的4个接口，推荐使用postman进行测试，可通过以下网盘链接下载

下载postmanicon-default.png?t=N7T8https://pan.baidu.com/s/1ViOqK6pp_Yj0Wfi2vAJsnA?pwd=yr5a好了，文章就分享到这里了，代码已开源，按需获取，如果这篇文章对你有所帮助，不要忘了点赞+收藏哦~

springboot+mybatis实现简单的增删查改案例项目icon-default.png?t=N7T8https://gitee.com/he-yunlin/springboot-crud.git

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