Spring Boot3.3.X整合Mybatis-Plus

前提说明：

项目的springboot版本为：<version>3.3.2</version>

需要整合的mybatis-plus版本：<version>3.5.7</version>

废话不多说，开始造吧

1.准备好数据库和表

2.配置全局文件application.properties或者是application.yml（配置mapper的映射文件路径）

我这里是application.properties，配置如下：

#配置服务器端口号
server.port=9090
#连接数据库
spring.application.name=dormitory_backend
spring.datasource.url=jdbc:mysql://localhost:3306/dormitory?allowPublicKeyRetrieval=true&serverTimezone=Asia/Shanghai&useSSL=false
spring.datasource.username=root
spring.datasource.password=root
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver#mybatis-plus配置mapper文件路径
mybatis-plus.mapper-locations=classpath:/mapper/*.xml
#打印sql日志
mybatis-plus.configuration.log-impl=org.apache.ibatis.logging.stdout.StdOutImpl
logging.level.com.dormitory.dormitory_backend.mapper=DEBUG

3.启动类配置包扫描注解和路径信息

配置之前先看下我这边的包结构

启动类，造吧？找到有@SpringBootApplication注解的类就是了，在其位置加上包扫描注解@MapperScan("com.dormitory.dormitory_backend.mapper")

注意括号里面的内容需要根据自己的包结构来配置，com.dormitory.dormitory_backend是我的包结构，主要看java，实在不懂，那就任意打开一个XXXmapper.java文件，看其包结构，框起来的一整个复制粘贴上去就可以了

4.导入依赖：

无效依赖---我尝试过导入网上的各种mybatis-plus的依赖：

<dependency><groupId>com.baomidou</groupId><artifactId>mybatis-plus-boot-starter</artifactId><version>3.5.1</version>
</dependency>
<dependency><groupId>com.baomidou</groupId><artifactId>mybatis-plus-annotation</artifactId><version>3.5.1</version>
</dependency>
<dependency><groupId>com.baomidou</groupId><artifactId>mybatis-plus-core</artifactId><version>3.5.1</version>
</dependency>

至于为什么说是无效依赖，导入以上的依赖无法使用mybatis-plus自带的方法

发送请求时，后台产生以下报错：

Invalid bound statement (not found): com.dormitory.dormitory_backend.mapper.AttendanceMapper.deleteById

AttendanceMapper的deleteById方法是无效的绑定语句，也就是，无法识别到mybatis-plus自带的删除方法，但是可以识别自定义的mapper语句，能正常进行增删改查，也就是原mybatis的写法呗，但是，我想快速实现CRUD啊！于是，网上找了一个解决的方法，配置一个类，请看下文：

import com.baomidou.mybatisplus.core.MybatisConfiguration;
import com.baomidou.mybatisplus.core.MybatisXMLLanguageDriver;
import com.baomidou.mybatisplus.core.toolkit.ObjectUtils;
import com.baomidou.mybatisplus.extension.plugins.inner.PaginationInnerInterceptor;
import com.baomidou.mybatisplus.extension.spring.MybatisSqlSessionFactoryBean;
import org.apache.ibatis.mapping.DatabaseIdProvider;
import org.apache.ibatis.plugin.Interceptor;
import org.mybatis.spring.boot.autoconfigure.MybatisProperties;
import org.mybatis.spring.boot.autoconfigure.SpringBootVFS;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.io.DefaultResourceLoader;
import org.springframework.core.io.ResourceLoader;
import org.springframework.util.StringUtils;import javax.sql.DataSource;@Configuration
public class MybatisPlusConfig {@Autowiredprivate DataSource dataSource;@Autowiredprivate MybatisProperties properties;@Autowiredprivate ResourceLoader resourceLoader = new DefaultResourceLoader();@Autowired(required = false)private Interceptor[] interceptors;@Autowired(required = false)private DatabaseIdProvider databaseIdProvider;/*** mybatis-plus分页插件*/@Beanpublic PaginationInnerInterceptor paginationInnerInterceptor(){PaginationInnerInterceptor page= new PaginationInnerInterceptor();return page;}/*** 这里全部使用mybatis-autoconfigure 已经自动加载的资源。不手动指定 <p> 配置文件和mybatis-boot的配置文件同步 @return*/@Beanpublic MybatisSqlSessionFactoryBean mybatisSqlSessionFactoryBean() {MybatisSqlSessionFactoryBean mybatisPlus = new MybatisSqlSessionFactoryBean();mybatisPlus.setDataSource(dataSource);mybatisPlus.setVfs(SpringBootVFS.class);if (StringUtils.hasText(this.properties.getConfigLocation()))mybatisPlus.setConfigLocation(this.resourceLoader.getResource(this.properties.getConfigLocation()));if (!ObjectUtils.isEmpty(this.interceptors)) mybatisPlus.setPlugins(this.interceptors);MybatisConfiguration mc = new MybatisConfiguration();mc.setDefaultScriptingLanguage(MybatisXMLLanguageDriver.class);// 数据库字段设计为驼峰命名，默认开启的驼峰转下划线会报错字段找不到mc.setMapUnderscoreToCamelCase(true);mybatisPlus.setConfiguration(mc);if (this.databaseIdProvider != null) mybatisPlus.setDatabaseIdProvider(this.databaseIdProvider);if (StringUtils.hasLength(this.properties.getTypeAliasesPackage()))mybatisPlus.setTypeAliasesPackage(this.properties.getTypeAliasesPackage());if (StringUtils.hasLength(this.properties.getTypeHandlersPackage()))mybatisPlus.setTypeHandlersPackage(this.properties.getTypeHandlersPackage());if (!ObjectUtils.isEmpty(this.properties.resolveMapperLocations()))mybatisPlus.setMapperLocations(this.properties.resolveMapperLocations());return mybatisPlus;}
}

配置了这个类，确实是可以使用mybatis-plus自带的方法，但是自己写的方法却无法实现了

实现配置类后，请求自定义的新增方法：

实现配置类后，请求mybatis-plus自带的删除方法：

几经辗转，发现导入以下这个依赖可以实现同时使用自定义方法和mybatis-plus自带方法，注意：需要删除MybatisPlusConfig类，以及将原先导入的三个依赖替换成新的依赖就可以了

有效依赖---导入mybatis-plus的依赖：

---------------原依赖-----------------
<dependency><groupId>com.baomidou</groupId><artifactId>mybatis-plus-boot-starter</artifactId><version>3.5.1</version>
</dependency>
<dependency><groupId>com.baomidou</groupId><artifactId>mybatis-plus-annotation</artifactId><version>3.5.1</version>
</dependency>
<dependency><groupId>com.baomidou</groupId><artifactId>mybatis-plus-core</artifactId><version>3.5.1</version>
</dependency>--------------新依赖------------------
<dependency><groupId>com.baomidou</groupId><artifactId>mybatis-plus-spring-boot3-starter</artifactId><version>3.5.7</version>
</dependency>

5.实现表对应的实体类

import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.annotation.TableField;
import com.baomidou.mybatisplus.annotation.TableId;
import com.baomidou.mybatisplus.annotation.TableName;
import io.swagger.annotations.ApiModelProperty;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;@Data
@AllArgsConstructor
@NoArgsConstructor
@TableName("t_attendance")
public class Attendance {@ApiModelProperty("自增id")@TableId(value = "id",type = IdType.AUTO)private Integer id;@ApiModelProperty("账号(学号)")@TableField("user_account")private String userAccount;@ApiModelProperty("缺勤原因")@TableField("reason")private String reason;
}

6.mapper和xml

import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.dormitory.dormitory_backend.entity.Attendance;
import org.apache.ibatis.annotations.Mapper;@Mapper
public interface AttendanceMapper extends BaseMapper<Attendance> {int insertAttendance(Attendance attendance);int deleteAttendance(Integer id);
}

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapperPUBLIC "-//mybatis.org//DTD Mapper 3.0//EN""https://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.dormitory.dormitory_backend.mapper.AttendanceMapper"><insert id="insertAttendance" parameterType="com.dormitory.dormitory_backend.entity.Attendance">insert into t_attendance(user_account,reason) values(#{userAccount},#{reason})</insert><delete id="deleteAttendance">delete from t_attendance where id = #{id}</delete></mapper>

7.service和impl

public interface AttendanceService {int addAttendance(Attendance attendance);int deleteAttendance(Integer id);
}

import com.dormitory.dormitory_backend.entity.Attendance;
import com.dormitory.dormitory_backend.mapper.AttendanceMapper;
import com.dormitory.dormitory_backend.service.AttendanceService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;@Service
public class AttendanceServiceImpl implements AttendanceService {@Autowiredprivate AttendanceMapper attendanceMapper;/*** 自定义的新增方法* @param attendance* @return*/@Overridepublic int addAttendance(Attendance attendance) {int insert = attendanceMapper.insertAttendance(attendance);return insert;}/*** plus自带的删除方法* @param id* @return*/@Overridepublic int deleteAttendance(Integer id) {return attendanceMapper.deleteById(id);}
}

8.controller

import com.dormitory.dormitory_backend.entity.Attendance;
import com.dormitory.dormitory_backend.service.AttendanceService;
import io.swagger.annotations.Api;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;@RestController
@RequestMapping("/attendance")
@Api(tags = {"考勤管理"})
public class AttendanceController {@Autowiredprivate AttendanceService attendanceService;@PostMapping("/addAttendance")public int addAttendance(@RequestBody Attendance attendance){int addAttendance = attendanceService.addAttendance(attendance);return addAttendance;}@DeleteMapping("/deleteAttendance")public int deleteAttendance(Integer id){int addAttendance = attendanceService.deleteAttendance(id);return addAttendance;}
}

9.实现

唠一唠：出现Invalid bound statement (not found)问题的原因可能有哪些

1.全局配置文件没配好？

检查全局配置文件application.properties或application.yml是否配置扫描mapper包的文件路径

#mybatis配置mapper文件路径
#mybatis.mapper-locations=classpath:/mapper/*.xml
#mybatis-plus配置mapper文件路径
mybatis-plus.mapper-locations=classpath:/mapper/*.xml

2.启动类没加包扫描注解 ？

检查启动类上是否添加包扫描注解 

@SpringBootApplication
@MapperScan("项目路径.mapper")
public class DormitoryBackendApplication {public static void main(String[] args) {SpringApplication.run(DormitoryBackendApplication.class, args);
}

3.没使用@Mapper注解？

XXXmapper.java类是否使用@Mapper注解

@Mapper
public interface AttendanceMapper extends BaseMapper<Attendance> {}

4.命名空间不正确？

检查XXXmapper.xml的命名空间是否正确，是否能跳转到对应的XXXmapper.java

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapperPUBLIC "-//mybatis.org//DTD Mapper 3.0//EN""https://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.dormitory.dormitory_backend.mapper.AttendanceMapper"></mapper>

正常能跳转会有箭头图标，点击能跳转（下载一个插件）