MybatisPlus：SQL语句打印、SQL分析、自定义主键值策略填充（IdType.INPUT）、动态表名、多租户、枚举、...

pom.xml - 依赖

<dependencies>                   <dependency>             <groupId>org.springframework.bootgroupId>             <artifactId>spring-boot-starter-webartifactId>         dependency>                   <dependency>             <groupId>mysqlgroupId>             <artifactId>mysql-connector-javaartifactId>             <scope>runtimescope>         dependency>                   <dependency>             <groupId>org.projectlombokgroupId> <artifactId>lombokartifactId> dependency>  <dependency> <groupId>com.baomidougroupId> <artifactId>mybatis-plus-boot-starterartifactId> <version>3.3.2version> dependency>  <dependency> <groupId>org.springframework.bootgroupId> <artifactId>spring-boot-devtoolsartifactId> dependency>  <dependency> <groupId>org.springframework.bootgroupId> <artifactId>spring-boot-starter-testartifactId> <scope>testscope> <exclusions> <exclusion> <groupId>org.junit.vintagegroupId> <artifactId>junit-vintage-engineartifactId> exclusion> exclusions> dependency> dependencies> 

application.yml

spring:
  application:
    name: mybatisplusStudy
  datasource:
    data-password: root
    password: root
    username: 123456
    url: jdbc:mysql://localhost:3306/interview?serverTimezone=UTC&useSSL=false
    driver-class-name: com.mysql.cj.jdbc.Driver

server:
  servlet:
    context-path: /mybatisplus
  port: 80


mybatis-plus:

  # mapper文件的位置
  mapper-locations: classpath:/mappers/*Mapper.xml

  # 哪个包下的类名可以在mapper文件中不用写全限定名，写类名即可
  type-aliases-package: top.linruchang.mybatisplusstudy.dto
  configuration:
    # 默认true - 数据库字段名 与 JavaBean属性名的对应关系
    # 查询数据库时
    # 1. true 数据库字段名中的下划线去掉并toUpperCase = JavaBean属性名.toUpperCase
    # 2. false 数据库字段名.toUpperCase = JavaBean属性名.toUpperCase
    # update、set数据库时
    # 1. true 只要是驼峰的JavaBean字段，会将驼峰的大写字母 变成 _小写字母
    # 2. false 数据库字段 = JavaBean属性字段
    map-underscore-to-camel-case: false
   #打印SQL日志
   log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
    global-config:
      db-config:
        # @FieldId 默认类型为自增长
        id-type: auto
         # @TableName如果要使用需要设置@TableName的属性是keepGlobalPrefix为true
        table-prefix: test_
        

MyConfig.java - 使MyBatis-plus分页起效

@Configuration
public class MyConfig { 
        

    @Bean
    public PaginationInterceptor getPaginationInterceptor() { 
        
        return new PaginationInterceptor();
    }

}

BaseDTO.java、ClassType.java

@Data
public class BaseDTO { 
        

    @TableId(type=IdType.AUTO)
    Integer id;

}


@TableName("class_type")
@Data
@Builder
public class ClassType extends BaseDTO { 
        

    @TableField("classNo")
    Integer classNo;

    @TableField("description")
    String description;

}

ClassTypeDao.java

@Mapper
public interface ClassTypeDao extends BaseMapper<ClassType>{ 
        


}

测试

@SpringBootTest
class SpringbootMybatisplusApplicationTests { 
        

    @Autowired
    ClassTypeDao classTypeDao;

    @Test
    public void test2() { 
        
        IPage<ClassType> classTypeIPage = classTypeDao.selectPage(new Page<>(1, 1), new QueryWrapper<ClassType>().gt("id", 0));

        List<ClassType> records = classTypeIPage.getRecords();

        records.forEach(System.out::println);
    }
}

# wrapper.getSqlSegment()  === 无where关键字 
(sys_user.id LIKE #{ew.paramNameValuePairs.MPGENVAL1} AND friendly_link.name = #{ew.paramNameValuePairs.MPGENVAL2} OR nick_name LIKE #{ew.paramNameValuePairs.MPGENVAL3})


# wrapper.wrapper.getCustomSqlSegment()  === 有where关键字
WHERE (sys_user.id LIKE #{ew.paramNameValuePairs.MPGENVAL1} AND friendly_link.name = #{ew.paramNameValuePairs.MPGENVAL2} OR nick_name LIKE #{ew.paramNameValuePairs.MPGENVAL3})


# wrapper.getTargetSql()  == 带问号参数sql非mybatis的手写sql == 即JDBC形式的SQL
(sys_user.id LIKE ? AND friendly_link.name = ? OR nick_name LIKE ?)

@TableName("student")
public class Student { 
        
    
    //如果数据库该表的主键不是自增长，且不能为null，则用实体类插入数据到数据库时主键必须有值，否则报错
    @TableId(type=IdType.INPUT)
    Integer id;

}

实现填充处理器MetaObjectHandler

@Component
@Slf4j
public class MyMetaObjectHandler implements MetaObjectHandler { 
        
    @Override
    public void insertFill(MetaObject metaObject) { 
        

        log.info("插入操作。。。。。。。。。。。。");

        this.setInsertFieldValByName("updateTime", new Date(), metaObject);
        this.setInsertFieldValByName("createTime", new Date(), metaObject);
    }

    @Override
    public void updateFill(MetaObject metaObject) { 
        
        log.info("更新操作。。。。。。。。。。。。");

        this.setInsertFieldValByName("updateTime", new Date(), metaObject);
    }
}

 
 
添加填充注解属性

@TableName("student")
@Data
@Builder
@NoArgsConstructor
@AllArgsConstructor
public class Student extends BaseDTO { 
        

    @TableField("name")
    String name;

    @TableField("sport")
    String sport;
	
	//FieldFill.DEFAULT默认填充不进行处理
    @TableField(value="create_time", fill = FieldFill.INSERT)
    Date createTime;

    @TableField(value="update_time", fill = FieldFill.INSERT_UPDATE)
    Date updateTime;

}

 
 
测试

    @Test
    public void test7() { 
        

        Student student = new Student();
        student.setId("fbc629c6703f0d8188476feb33c1f41f");
        student.setName("ewoi");
        student.setSport("8764431");

        int flag = studentDao.updateById(student);

        System.out.println(flag);

    }

开启乐观锁SQL拦截器

@Configuration
@EnableTransactionManagement
public class MyConfig { 
        

    @Bean
    public OptimisticLockerInterceptor getOptimisticLockerInterceptor() { 
        
        return new OptimisticLockerInterceptor();
    }

}

添加字段version字段

@Data
public class BaseDTO { 
        

    @TableId(type=IdType.UUID)
    String id;
    
    //乐观锁注解开启
    @Version
    Integer version;

}


@TableName("student")
@Data
@ToString(callSuper=true)
@Builder
@NoArgsConstructor
@AllArgsConstructor
public class Student extends BaseDTO { 
        

    @TableField("name")
    String name;

    @TableField("sport")
    String sport;

    @TableField(value="create_time", fill = FieldFill.INSERT)
    Date createTime;

    @TableField(value="update_time", fill = FieldFill.INSERT_UPDATE)
    Date updateTime;

}

 
 
测试

    @Test
    public void test8() { 
        

        Student student = studentDao.selectById("fsfsd");

        System.out.println(student);

        student.setSport("做爱做的侍寝111");

        studentDao.updateById(student);

        student = studentDao.selectById("fsfsd");

        System.out.println(student);


    }

实体类Student以及与该表交互的StudentDao