/**
* Twitter的分布式自增ID雪花算法
**/
@Component
public class SnowFlake {
/**
* 起始的时间戳
*/
private final static long START_STMP = 1609459200000L; // 2021-01-01 00:00:00
/**
* 每一部分占用的位数
*/
private final static long SEQUENCE_BIT = 12; //序列号占用的位数
private final static long MACHINE_BIT = 5; //机器标识占用的位数
private final static long DATACENTER_BIT = 5;//数据中心占用的位数
/**
* 每一部分的最大值
*/
private final static long MAX_DATACENTER_NUM = -1L ^ (-1L << DATACENTER_BIT);
private final static long MAX_MACHINE_NUM = -1L ^ (-1L << MACHINE_BIT);
private final static long MAX_SEQUENCE = -1L ^ (-1L << SEQUENCE_BIT);
/**
* 每一部分向左的位移
*/
private final static long MACHINE_LEFT = SEQUENCE_BIT;
private final static long DATACENTER_LEFT = SEQUENCE_BIT + MACHINE_BIT;
private final static long TIMESTMP_LEFT = DATACENTER_LEFT + DATACENTER_BIT;
private long datacenterId = 1; //数据中心
private long machineId = 1; //机器标识
private long sequence = 0L; //序列号
private long lastStmp = -1L;//上一次时间戳
public SnowFlake() {
}
public SnowFlake(long datacenterId, long machineId) {
if (datacenterId > MAX_DATACENTER_NUM || datacenterId < 0) {
throw new IllegalArgumentException("datacenterId can't be greater than MAX_DATACENTER_NUM or less than 0");
}
if (machineId > MAX_MACHINE_NUM || machineId < 0) {
throw new IllegalArgumentException("machineId can't be greater than MAX_MACHINE_NUM or less than 0");
}
this.datacenterId = datacenterId;
this.machineId = machineId;
}
/**
* 产生下一个ID
*
* @return
*/
public synchronized long nextId() {
long currStmp = getNewstmp();
if (currStmp < lastStmp) {
throw new RuntimeException("Clock moved backwards. Refusing to generate id");
}
if (currStmp == lastStmp) {
//相同毫秒内，序列号自增
sequence = (sequence + 1) & MAX_SEQUENCE;
//同一毫秒的序列数已经达到最大
if (sequence == 0L) {
currStmp = getNextMill();
}
} else {
//不同毫秒内，序列号置为0
sequence = 0L;
}
lastStmp = currStmp;
return (currStmp - START_STMP) << TIMESTMP_LEFT //时间戳部分
| datacenterId << DATACENTER_LEFT //数据中心部分
| machineId << MACHINE_LEFT //机器标识部分
| sequence; //序列号部分
}
private long getNextMill() {
long mill = getNewstmp();
while (mill <= lastStmp) {
mill = getNewstmp();
}
return mill;
}
private long getNewstmp() {
return System.currentTimeMillis();
}
}
上边的代码都没有什么难度，下面就开始实现用户管理的逻辑部分。
三、🚆后端新增接口
在UserController类中需要小小的修改一下。
java复制代码
@RestController
@RequestMapping("/user")
public class UserController {
@Autowired
private UserService userService;
}
3.1 /user/list接口添加
其实这样的代码已经写了不少了，这样的list查询并没有什么难度，
java复制代码
@RequestMapping("/list")
public CommonResp list(@Validated UserQueryParam userQueryParam){
PageVo<UserQueryVo> list = userService.list(userQueryParam);
return new CommonResp(true,"查找成功", list);
}
