package com.shinedata.util;
import com.yeepay.shade.org.apache.commons.lang3.StringUtils;
/**
* @ClassName SystemConversionUtils 進制轉換
* @Author yupanpan
* @Date 2019/9/27 9:41
*/
public class SystemConversionUtils {
/**
* 初始化 62 進制數據,索引位置代表字符的數值,比如 A代表10,z代表61等
*/
private static String chars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
private static int scale = 62;
/**
* 10進制轉爲62進制
* @param num Long 型數字
* @return 62進制字符串 如果不夠6個長度,左側填充0,例:000asf
*/
public static String base62Encode(long num) {
StringBuilder sb = new StringBuilder();
int remainder = 0;
while (num > scale - 1) {
remainder = Long.valueOf(num % scale).intValue();
sb.append(chars.charAt(remainder));
num = num / scale;
}
sb.append(chars.charAt(Long.valueOf(num).intValue()));
String value = sb.reverse().toString();
return StringUtils.leftPad(value, 6, '0');
}
/**
* 62進制字符串轉爲10進制
* @param str 編碼後的62進制字符串
* @return 解碼後的 10 進制字符串
*/
public static long base62Decode(String str) {
str = str.replace("^0*", "");
long num = 0;
int index = 0;
for (int i = 0; i < str.length(); i++) {
index = chars.indexOf(str.charAt(i));
num += (long) (index * (Math.pow(scale, str.length() - i - 1)));
}
return num;
}
}
SnowFlake生成唯一ID
package com.shinedata;
import com.shinedata.util.SystemConversionUtils;
/**
* @ClassName SnowFlake
* @Author yupanpan
* @Date 2019/9/26 17:18
*/
public class SnowFlake {
/**
* 起始的時間戳
*/
private final static long START_STMP = 1480166465631L;
/**
* 每一部分佔用的位數
*/
private final static long SEQUENCE_BIT = 12; //序列號佔用的位數
private final static long MACHINE_BIT = 5; //機器標識佔用的位數
private final static long DATACENTER_BIT = 5;//數據中心佔用的位數
/**
* 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; //數據中心
private long machineId; //機器標識
private long sequence = 0L; //序列號
private long lastStmp = -1L;//上一次時間戳
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;
}
/**
* 產生下一個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) {
//相同毫秒內,序列號自增
sequence = (sequence + 1) & MAX_SEQUENCE;
//同一毫秒的序列數已經達到最大
if (sequence == 0L) {
currStmp = getNextMill();
}
} else {
//不同毫秒內,序列號置爲0
sequence = 0L;
}
lastStmp = currStmp;
return (currStmp - START_STMP) << TIMESTMP_LEFT //時間戳部分
| datacenterId << DATACENTER_LEFT //數據中心部分
| machineId << MACHINE_LEFT //機器標識部分
| sequence; //序列號部分
}
private long getNextMill() {
long mill = getNewstmp();
while (mill <= lastStmp) {
mill = getNewstmp();
}
return mill;
}
private long getNewstmp() {
return System.currentTimeMillis();
}
}
利用Twitter的SnowFlake算法生成一個唯一ID轉換測試
短連接以及用戶默認暱稱/ID號等業務場景下基本都可以使用