一、介绍
二、SQL
CREATE TABLE bits_table (id INT PRIMARY KEY AUTO_INCREMENT,bit_value BIGINT UNSIGNED
);-- 插入一个 8 位的 BIT 值
INSERT INTO bits_table (bit_value) VALUES (B'10101010');-- 查询并格式化输出
SELECT id,bit_value,CONCAT('b', LPAD(BIN(bit_value), 64, '0')) AS formatted_bit_value -- 将 BIGINT 转换为 64 位的二进制字符串
FROM bits_table;在这个例子中，CONCAT('b', LPAD(BIN(bit_value), 64, '0')) 用于将 bit_value 转换为一个以 'b' 开头的 64 位二进制字符串，LPAD 用于在左边填充 '0' 以达到 64 位的长度。
请注意，如果你需要存储非整数数量的位或者位数不固定，你可能需要以文本形式存储或者使用其他数据库特性来实现。
-- 假设我们有一个表 `bits_table`，其中有一个 `BIGINT` 类型的列 `bigint_col`
-- 我们要修改 `bigint_col` 列的第二位-- 将 `bigint` 转换为 `bit` 字符串，并取得第二位的值
SELECT bigint_col,-- 将 `bigint` 转换为 `bit` 字符串，并取得第二位的值SUBSTRING(BIN(bigint_col), 2, 1) AS second_bit
FROMbits_table;-- 更新第二位为1
UPDATE bits_table
SET bigint_col = -- 将 `bigint` 转换为 `bit` 字符串，将第二位设置为1，然后转换回 `bigint`(CONV(CONCAT(SUBSTRING(BIN(bigint_col), 1, 1), '1', SUBSTRING(BIN(bigint_col), 3)), 2, 10)
WHERE-- 你的条件语句，比如 id = 1id = 1;<!-- MyBatis的mapper文件 -->
<update id="updateBit">UPDATE your_table_nameSET your_bigint_column = bitor(bitand(your_bigint_column, bnot(1 << 20)), (#{value} << 20))WHERE your_condition
</update>这里使用了两个位运算符：bitand(a, b): 对两个bigint数进行按位与操作。bitor(a, b): 对两个bigint数进行按位或操作。bnot(x): 对bigint数进行按位取反操作，结果是把x的第y位取反。<<: 左移运算符，用于将一个整数左移指定的位数。确保你的mapper接口中有相应的方法：UPDATE your_table_name
SET your_bigint_column = BIN(CONV(CONV(your_bigint_column, 2, 10) + POW(2, 19 - 1), 2, 10))
WHERE your_condition;your_table_name是你的表名，your_bigint_column是你想要更新的列名，your_condition是你的更新条件。请注意，这个例子中假设了以下几点：你想要将第20位设置为1。你的列是无符号的，因此最高位是第20位。如果是有符号的，请适当调整位数。如果你想将第20位设置为0或某个特定值，只需要将POW(2, 19 - 1)中的1改为你想要设置的值（以二进制表示）。如果是将第20位设置为0，就是POW(2, 19 - 0)三、demo
1、使用bigint类型存储bit
总览
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><groupId>org.example</groupId><artifactId>bit-demo</artifactId><version>1.0-SNAPSHOT</version><parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>3.2.4</version><relativePath/></parent><properties><maven.compiler.source>17</maven.compiler.source><maven.compiler.target>17</maven.compiler.target><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding></properties><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><!--尽量不要同时导入mybatis 和 mybatis_plus，避免版本差异--><dependency><groupId>com.baomidou</groupId><artifactId>mybatis-plus-spring-boot3-starter</artifactId><version>3.5.5</version></dependency><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>8.0.13</version></dependency><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope></dependency><dependency><groupId>junit</groupId><artifactId>junit</artifactId><scope>test</scope></dependency></dependencies></project>server.port=6666
server.servlet.context-path=/bitDemo
#mysql
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3308/demo?useUnicode=true&characterEncoding=utf-8&useSSL=false
spring.datasource.username=root
spring.datasource.password=wtyy
#mybatis
mybatis.mapper-locations=classpath*:mapper/*Mapper.xml
#
mybatis-plus.configuration.log-impl=org.apache.ibatis.logging.stdout.StdOutImpl1.1、表
create table demo.user_sys_flag
(id int auto_incrementprimary key,flag bigint null,user_id varchar(50) null
);1.2、dto与枚举
package com.bit.demo.dto;import com.baomidou.mybatisplus.annotation.TableName;
import com.bit.demo.enums.UserSysFlagEnums;
import com.bit.demo.util.BitUtil;
import lombok.Builder;
import lombok.Data;@Data
@Builder
@TableName("user_sys_flag")
public class UserSysFlagDTO {private Integer id;private Long flag;private String userId;public boolean isEnableFlag1(){return BitUtil.isSet(flag,UserSysFlagEnums.FLAG_1.bitPosition);}public boolean isEnableFlag2(){return BitUtil.isSet(flag,UserSysFlagEnums.FLAG_2.bitPosition);}public boolean isEnableFlag60() {return BitUtil.isSet(flag,UserSysFlagEnums.FLAG_60.bitPosition);}
}
package com.bit.demo.enums;public enum UserSysFlagEnums {FLAG_1("flag_1",1L),FLAG_2("flag_2",1L<<1),FLAG_3("flag_3",1L<<2),FLAG_60("flag_60",1L<<59);public final String key;public final Long bitPosition;UserSysFlagEnums(String key, Long bitPosition){this.key = key;this.bitPosition = bitPosition;}
}
1.3、dao
package com.bit.demo.repository;import com.baomidou.mybatisplus.core.conditions.AbstractWrapper;
import com.baomidou.mybatisplus.core.conditions.Wrapper;
import com.baomidou.mybatisplus.core.conditions.query.LambdaQueryWrapper;
import com.bit.demo.dto.UserSysFlagDTO;
import com.bit.demo.mapper.UserSysFlagMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Repository;@Repository
public class UserSysFlagRepository {@Autowiredpublic UserSysFlagMapper userSysFlagMapper;public void insert(UserSysFlagDTO userSysFlagDTO) {userSysFlagMapper.insert(userSysFlagDTO);}public UserSysFlagDTO getByUserId(String userId) {LambdaQueryWrapper<UserSysFlagDTO> userQuery = new LambdaQueryWrapper<>();userQuery.eq(UserSysFlagDTO::getUserId,userId);return userSysFlagMapper.selectOne(userQuery);}public void updateFlagByUserIdAndIndex(String userId, int index, int indexValue) {userSysFlagMapper.updateFlagByUserIdAndIndex(userId,index,indexValue);}public String queryBitByUserId(Integer bitLength,String userId) {return userSysFlagMapper.queryBitByUserId(bitLength,userId);}
}
package com.bit.demo.mapper;import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.bit.demo.dto.UserSysFlagDTO;
import org.apache.ibatis.annotations.Param;public interface UserSysFlagMapper extends BaseMapper<UserSysFlagDTO> {void updateFlagByUserIdAndIndex(@Param("userId") String userId,@Param("index") int index,@Param("bitValue") int bitValue);String queryBitByUserId(@Param("bitLength")Integer bitLength,@Param("userId") String userId);
}
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapperPUBLIC "-//mybatis.org//DTD Mapper 3.0//EN""http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.bit.demo.mapper.UserSysFlagMapper"><update id="updateFlagByUserIdAndIndex">UPDATE user_sys_flagSET flag =CASEWHEN #{bitValue} = 1 THEN flag | (1 << ${index}) <!-- Setting the 20th bit to 1 -->ELSE flag & ~(1 << ${index}) <!-- Setting the 20th bit to 0 -->ENDwhere user_id=#{userId}</update><select id="queryBitByUserId" resultType="string">SELECTCONCAT('b', LPAD(BIN(flag), ${bitLength}, '0')) AS formatted_bit_valueFROMuser_sys_flag WHEREuser_id = #{userId}</select></mapper>1.4、service
package com.bit.demo.service.impl;import com.bit.demo.dto.UserSysFlagDTO;
import com.bit.demo.mapper.UserSysFlagMapper;
import com.bit.demo.repository.UserSysFlagRepository;
import com.bit.demo.service.UserSysFlagService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;@Service("userSysFlagService")
public class UserSysFlagServiceImpl implements UserSysFlagService {@Autowiredprivate UserSysFlagRepository userSysFlagRepository;@Autowiredprivate UserSysFlagMapper userSysFlagMapper;@Overridepublic void insert(UserSysFlagDTO userSysFlagDTO) {userSysFlagRepository.insert(userSysFlagDTO);}@Overridepublic UserSysFlagDTO getByUserId(String userId) {return userSysFlagRepository.getByUserId(userId);}@Overridepublic void updateFlagByUserIdAndIndex(String userId, int index, int indexValue) {userSysFlagRepository.updateFlagByUserIdAndIndex(userId,index,indexValue);}@Overridepublic String queryBitByUserId(Integer bitLength,String userId) {return userSysFlagRepository.queryBitByUserId(bitLength,userId);}
}
1.5、util
package com.bit.demo.util;import com.bit.demo.enums.UserSysFlagEnums;public class BitUtil {public static boolean isSet(long options, long bit) {return (options & bit) == bit;}
}
1.6、启动类
package com.bit.demo;import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;@MapperScan("com.bit.demo.mapper")
@SpringBootApplication
public class BitApplication {public static void main(String[] args) {SpringApplication.run(BitApplication.class, args);}
}
1.7、test
package com.bit.demo;import com.bit.demo.dto.UserSysFlagDTO;
import com.bit.demo.service.UserSysFlagService;
import lombok.extern.slf4j.Slf4j;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;@SpringBootTest(classes = {BitApplication.class}, webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
@RunWith(SpringRunner.class)
@Slf4j
public class UserSysFlagTest {@Autowiredprivate UserSysFlagService userSysFlagService;//1、初始化。最大64位，假如需要60个开关，0代表关，1代表开，默认为关。@Testpublic void init() {UserSysFlagDTO userSysFlagDTO = UserSysFlagDTO.builder().userId("zs").flag(0L).build();userSysFlagService.insert(userSysFlagDTO);}//2、更新,更新第n位的flag@Testpublic void update() {//将 `bigint` 转换为 `bit` 字符串，将第index位设置为indexValue，然后转换回 `bigint`//index从0开始String userId = "zs";int index = 0;int indexValue = 0;userSysFlagService.updateFlagByUserIdAndIndex(userId,index,indexValue);}//3、查询@Testpublic void query() {UserSysFlagDTO userSysFlagDTO = userSysFlagService.getByUserId("zs");log.info(userSysFlagDTO.toString());log.info("flag1值为：{}", userSysFlagDTO.isEnableFlag1());log.info("flag2值为：{}", userSysFlagDTO.isEnableFlag2());log.info("flag60值为：{}", userSysFlagDTO.isEnableFlag60());}//查询二进制@Testpublic void queryBit(){Integer bitLength = 64;String userId = "zs";String bitStr = userSysFlagService.queryBitByUserId(bitLength,userId);System.out.println(bitStr);}
}
1.8、测试：
（1）初始化
如我初始化了ls，默认是0
（2）更新第1位
更新ls第1位为1
String userId = "ls";int index = 0;int indexValue = 1;queryBit：可以看到第一位是1了
query：可以看到isEnableFlag1是true了
（3）更新其他位
如更新第60位为1：
String userId = "ls";int index = 59;int indexValue = 1;queryBit：可以看到第60位是1了
query：可以看到isEnableFlag1、isEnableFlag60都是true了
（4）再次更新第1位
更新为0，也即关闭功能
String userId = "ls";int index = 0;int indexValue = 0;queryBit查看：
query查看：
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