MyBatis-Plus主键策略(雪花算法16位长度的整型id,解决默认雪花算法生成19位长度id导致JS精度丢失问题)
js表达的最大整数2的53次方减1,精度丢失后面几位全是0!
主键策略
如果内置支持不满足你的需求,可实现 IKeyGenerator 接口来进行扩展.
举个栗子
@KeySequence(value = "SEQ_ORACLE_STRING_KEY", clazz = String.class)
public class YourEntity {
@TableId(value = "ID_STR", type = IdType.INPUT)
private String idStr;
}
#Spring-Boot
#方式一:使用配置类
@Bean
public IKeyGenerator keyGenerator() {
return new H2KeyGenerator();
}
#方式二:通过 MybatisPlusPropertiesCustomizer 自定义
@Bean
public MybatisPlusPropertiesCustomizer plusPropertiesCustomizer() {
return plusProperties -> plusProperties.getGlobalConfig().getDbConfig().setKeyGenerator(new H2KeyGenerator());
}
#Spring
#方式一: XML 配置
#方式二:注解配置
@Bean
public GlobalConfig globalConfig() {
GlobalConfig conf = new GlobalConfig();
conf.setDbConfig(new GlobalConfig.DbConfig().setKeyGenerator(new H2KeyGenerator()));
return conf;
}
官方示例
官方id generator示例 https://gitee.com/baomidou/mybatis-plus-samples/tree/master/mybatis-plus-sample-id-generator
工程中16位长度的long整型id示例
@Component
public class CustomerIdGenerator implements IdentifierGenerator {
@Override
public Long nextId(Object entity) {
// 填充自己的Id生成器,
return IdGenerator.generateId();
}
}
import java.util.Date;
import java.util.UUID;
/**
* compressed id generator, result id not great than 53bits before 2318-06-04.
*/
public class IdGenerator {
private static IdGenerator instance = new IdGenerator(0);
public static IdGenerator initDefaultInstance(int machineId) {
instance = new IdGenerator(machineId);
return instance;
}
public static IdGenerator getInstance() {
return instance;
}
public static long generateId() {
return instance.nextId();
}
// total bits=53(max 2^53-1:9007199254740992-1)
// private final static long TIME_BIT = 40; // max: 2318-06-04
private final static long MACHINE_BIT = 5; // max 31
private final static long SEQUENCE_BIT = 8; // 256/10ms
/**
* mask/max value
*/
private final static long MAX_MACHINE_NUM = -1L ^ (-1L |