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 {
    @Autowired
    private DataSource dataSource;
    @Autowired
    private MybatisProperties properties;
    @Autowired
    private ResourceLoader resourceLoader = new DefaultResourceLoader();
    @Autowired(required = false)
    private Interceptor[] interceptors;
    @Autowired(required = false)
    private DatabaseIdProvider databaseIdProvider;

    /**
     * mybatis-plus分页插件
     */
    @Bean
    public 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
     */
    @Bean
    public 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 mapper
        PUBLIC "-//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 {
    @Autowired
    private AttendanceMapper attendanceMapper;

    /**
     * 自定义的新增方法
     * @param attendance
     * @return
     */
    @Override
    public int addAttendance(Attendance attendance) {
        int insert = attendanceMapper.insertAttendance(attendance);
        return insert;
    }

    /**
     * plus自带的删除方法
     * @param id
     * @return
     */
    @Override
    public 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 {
    @Autowired
    private 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 mapper
        PUBLIC "-//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）