spring boot+mybatis-plus+mysql_springboot mybatisplus mysql

1、版本：spring boot 2.7 +mybatis-plus 3.4
2、安装mybatis-plus依赖项

<dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.4.2</version>
        </dependency>
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3、表结构

4、项目结构

5、实体类

package com.example.springbootmybatisplus.pojo;

import com.baomidou.mybatisplus.annotation.*;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

import java.util.Date;

@TableName("user")
@Data
public class User {
  //对应数据库的主键（uuid，自增id，雪花算法,redis，zookper）
  @TableId(type = IdType.AUTO)
  private long id;
  private String name;
  private Integer age;
  private String email;

  //逻辑删除字段
  @TableLogic //逻辑删除注解
  private Integer deleted;

  //字段添加填充内容
  //策略
  @TableField(fill = FieldFill.INSERT)
  private LocalDateTime createTime;
  //策略
  @TableField(fill = FieldFill.INSERT_UPDATE)
  private LocalDateTime updateTime;
}

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注意：如果项目采用分层VO的话，对于处理返回前端多余字段需要加上@JsonInclude(JsonInclude.Include.NON_NULL)注解即可，那么则对于不需要的字段前端就不显示了
6、配置文件

server.port=xxxxx
#mysql连接配置，与mybatis一致
spring.datasource.url=jdbc:mysql://localhost:3306/xxxx?useUnicode=true&useJDBCCompliantTimezoneShift=true&useLegacyDatetimeCode=false&serverTimezone=GMT%2B8&allowMultiQueries=true&useUnicode=true&characterEncoding=UTF-8
spring.datasource.username=root
spring.datasource.password=xxxxxx
spring.datasource.driver-class-name= com.mysql.cj.jdbc.Driver
#mybatis-plus日志配置
mybatis-plus.configuration.log-impl=org.apache.ibatis.logging.stdout.StdOutImpl


# 配置逻辑删除
mybatis-plus.global-config.db-config.logic-delete-value=1
mybatis-plus.global-config.db-config.logic-not-delete-value=0
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7、启动文件配置mapper路径

package com.example.springbootmybatisplus;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
//扫描mapper文件夹
@MapperScan("com.example.springbootmybatisplus.mapper")
@SpringBootApplication
public class SpringbootmybatisplusApplication {

    public static void main(String[] args) {
        SpringApplication.run(SpringbootmybatisplusApplication.class, args);
    }

}

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8、dao层代码

package com.example.springbootmybatisplus.mapper;

import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.example.springbootmybatisplus.pojo.User;
import org.springframework.stereotype.Repository;

@Repository
public interface UserMapper extends BaseMapper<User> {
}

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9、create_time,update_time自动生成处理器配置类

package com.example.springbootmybatisplus.handler;

import com.baomidou.mybatisplus.core.handlers.MetaObjectHandler;
import lombok.extern.slf4j.Slf4j;
import org.apache.ibatis.reflection.MetaObject;
import org.springframework.stereotype.Component;

import java.util.Date;

@Slf4j
@Component //一定不要忘记把处理器加到IOC容器中
public class MyDataObjectHandler implements MetaObjectHandler {
    //插入时的填充策略
    @Override
    public void insertFill(MetaObject metaObject) {
        log.info("start insert fill");
        //setFieldValByName(String fieldName, Object fieldVal, MetaObject metaObject)
        this.setFieldValByName("createTime",LocalDateTime.now(),metaObject);
        this.setFieldValByName("updateTime",LocalDateTime.now(),metaObject);
    }
    //更新时的填充策略
    @Override
    public void updateFill(MetaObject metaObject) {
        log.info("start update fill");
        this.setFieldValByName("updateTime",new Date(),metaObject);
    }
}

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10、mybatis-plus分页插件配置类

package com.example.springbootmybatisplus.config;

import com.baomidou.mybatisplus.annotation.DbType;
import com.baomidou.mybatisplus.core.injector.ISqlInjector;
import com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor;
import com.baomidou.mybatisplus.extension.plugins.PaginationInterceptor;
import com.baomidou.mybatisplus.extension.plugins.inner.PaginationInnerInterceptor;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.transaction.annotation.EnableTransactionManagement;

//@EnableTransactionManagement
@Configuration // 配置类
public class MyBatisPlusConfig {
    //分页
    /**
     * 新的分页插件,一缓和二缓遵循mybatis的规则,需要设置 MybatisConfiguration#useDeprecatedExecutor = false 避免缓存出现问题
     */
    @Bean
    public MybatisPlusInterceptor mybatisPlusInterceptor() {
        MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();
        interceptor.addInnerInterceptor(new PaginationInnerInterceptor(DbType.MYSQL));
        return interceptor;
    }

    //@Bean public ISqlInjector sqlInjector() { return new LogicSqlInjector(); }
}

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11、引入dao的mapper操作对象

@Autowired
    private UserMapper userMapper;
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12、测试查询部分

//测试查询
    @Test
    public void testSelectById(){
        User user = userMapper.selectById(1000L);
        System.out.println(user);
    }

    @Test
    //批量查询
    public void testSelectByBatchId(){
        List<User> users = userMapper.selectBatchIds(Arrays.asList(4, 5, 8, 9));
        System.out.println(users);
    }

    //条件查询 map
    @Test
    public void testSelectByBatchIds(){
        HashMap<String, Object> map = new HashMap<>();
        map.put("name","mybatis-plus-test");
        map.put("age",89);
        List<User> users = userMapper.selectByMap(map);
        users.forEach(System.out::println);
    }
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13、测试分页查询部分

@Test
    //测试分页查询
    public void testPage(){
        //参数一：当前页
        //参数二：页面大小
        Page<User> page = new Page<>(1,5);
        Page<User> userPage = userMapper.selectPage(page, null);
//        page.getRecords().forEach(System.out::println);
//        //获取总数
//        System.out.println("总数：");
//        System.out.println(page.getTotal());
        System.out.println("查询结果");
        System.out.println(userPage.getRecords());
        System.out.println("总数");
        System.out.println(userPage.getTotal());
    }
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14、测试插入部分

//测试插入功能
    @Test
    public void testInsert(){
        User user = new User();
        user.setName("mybatis-18-plus-test18");
        user.setAge(18);
        user.setEmail("mabat-18test@qq.com");
        int result=userMapper.insert(user);
        System.out.println(result);
        System.out.println(user);
        System.out.println(user.getId());
    }
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15、测试更新部分

//更新
    @Test
    public void testUpdate(){
        User user = new User();
        user.setId(10L);
        user.setName("mybatis-plus-test");
        int i=userMapper.updateById(user);
        System.out.println(i);
    }
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16、测试删除部分（如何逻辑删除需在实体类做配置）

//删除操作
    @Test
    public  void testDeleteById(){
        int rows = userMapper.deleteById(1000L);
        System.out.println(rows);
    }

    //批量删除根据ID
    @Test
    public  void testDeleteBatchId(){
        userMapper.deleteBatchIds(Arrays.asList(996,997,998));
    }

    //通过map删除
    @Test
    public  void testDeleteMap(){
        HashMap<String, Object> map = new HashMap<>();
        map.put("name","叔叔婶婶");
        userMapper.deleteByMap(map);
    }
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17、注：实体类的时间映射，添加注解@JsonFormat(pattern = “yyyy-MM-dd”, timezone = “GMT+8”)
18、当updateById时，如果要插入空值，则在实体类上新增注解@TableField(updateStrategy = FieldStrategy.IGNORED)即可