在使用mybatisplus自带雪花的时候会发现返回的ID是19位的长度，因此在通过swagger页面展示的时候会发现后端返回的和页面展示的ID不一致问题。是因为精度丢失的问题。因此需要更改雪花ID的长度
跟踪进去：
发现是DefaultIdentifierGenerator类实现了IdentifierGenerator并重写了nextId方法,因此需要我们重写nextId方法
- 进行重写：
package com.ssdl.config.automatic;
import com.baomidou.mybatisplus.core.incrementer.IdentifierGenerator;
import com.ssdl.util.IdGenerator;
import org.springframework.stereotype.Component;
@Component
public class CustomerIdGenerator implements IdentifierGenerator {
@Override
public Number nextId(Object entity) {
return IdGenerator.generateId();
}
}
package com.ssdl.util;
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 << MACHINE_BIT);
private final static long MAX_SEQUENCE = -1L ^ (-1L << SEQUENCE_BIT);
private final static long MACHINE_LEFT = SEQUENCE_BIT;
private final static long TIMESTMP_LEFT = MACHINE_BIT + SEQUENCE_BIT;
private long machineId;
private long sequence = 0L;
private long lastStmp = -1L;
private IdGenerator(long machineId) {
if (machineId > MAX_MACHINE_NUM || machineId < 0) {
throw new IllegalArgumentException(
"machineId can't be greater than " + MAX_MACHINE_NUM + " or less than 0");
}
this.machineId = machineId;
}
/**
* generate new ID
*
* @return
*/
public synchronized long nextId() {
long currStmp = getTimestamp();
if (currStmp < lastStmp) {
throw new RuntimeException("Clock moved backwards. Refusing to generate id");
}
if (currStmp == lastStmp) {
sequence = (sequence + 1) & MAX_SEQUENCE;
if (sequence == 0L) {
currStmp = getNextTimestamp();
}
} else {
sequence = 0L;
}
lastStmp = currStmp;
return currStmp << TIMESTMP_LEFT //
| machineId << MACHINE_LEFT //
| sequence;
}
private long getNextTimestamp() {
long mill = getTimestamp();
while (mill <= lastStmp) {
mill = getTimestamp();
}
return mill;
}
private long getTimestamp() {
// per 10ms
return System.currentTimeMillis() / 10;// 10ms
}
public static Date parseIdTimestamp(long id) {
return new Date((id >>> TIMESTMP_LEFT) * 10);
}
public static String uuid() {
return UUID.randomUUID().toString().replaceAll("-", "");
}
}
插曲：
在使用mybatisplus时自动插入创建时间之类的操作：
package com.ssdl.config.autoMatic;
import com.baomidou.mybatisplus.core.handlers.MetaObjectHandler;
import org.apache.ibatis.reflection.MetaObject;
import org.springframework.stereotype.Component;
import java.util.Date;
@Component
public class MybatisHandler implements MetaObjectHandler {
@Override
public void insertFill(MetaObject metaObject) {
//属性名
this.setFieldValByName("createTime", new Date(), metaObject);
this.setFieldValByName("updateTime", new Date(), metaObject);
this.setFieldValByName("isDel", 0, metaObject);
this.setFieldValByName("createUser", "admin", metaObject);
this.setFieldValByName("updateUser", "admin", metaObject);
//this.setFieldValByName("createUser", SecureUtil.getUserId(), metaObject);
//不维护create_user可以不使用这行代码
}
@Override
public void updateFill(MetaObject metaObject) {
//属性名
this.setFieldValByName("updateTime", new Date(), metaObject);
this.setFieldValByName("updateUser", "admin", metaObject);
//this.setFieldValByName("updateUser", SecureUtil.getUserId(), metaObject);
}
}
@TableId(value = "id",type = IdType.ASSIGN_ID)
private Long id;
/**
* 进行新增或者更新操作时
* Mybatis自动进行维护时间
*/
@TableField(fill= FieldFill.INSERT)
private String createUser;
@TableField(fill=FieldFill.INSERT)
@JsonFormat(shape = JsonFormat.Shape.STRING, pattern = "yyyy-MM-dd HH:mm:ss", timezone = "GMT+8")
private Date createTime;
@TableField(fill=FieldFill.INSERT_UPDATE)
@JsonIgnore
private String updateUser;
@TableField(fill= INSERT_UPDATE)
@JsonIgnore
private Date updateTime;
@TableLogic
@TableField(fill= FieldFill.INSERT)
@JsonIgnore
private Integer isDel;
