【Flowable实战】Flowable6.4.1自定义id生成

zhangdaiscott · 发表于 2023-2-18 16:12:04

1. 雪花Id生成器

/**
* 雪花算法生成id
* @author
*
*/
public class Snowflake {
private final static long TWEPOCH = 1288834974657L;
// 机器标识位数
private final static long WORKER_ID_BITS = 5L;
// 数据中心标识位数
private final static long DATA_CENTER_ID_BITS = 5L;
// 机器ID最大值 31
private final static long MAX_WORKER_ID = -1L ^ (-1L << WORKER_ID_BITS);
// 数据中心ID最大值 31
private final static long MAX_DATA_CENTER_ID = -1L ^ (-1L << DATA_CENTER_ID_BITS);
// 毫秒内自增位
private final static long SEQUENCE_BITS = 12L;
// 机器ID偏左移12位
private final static long WORKER_ID_SHIFT = SEQUENCE_BITS;
private final static long DATA_CENTER_ID_SHIFT = SEQUENCE_BITS + WORKER_ID_BITS;
// 时间毫秒左移22位
private final static long TIMESTAMP_LEFT_SHIFT = SEQUENCE_BITS + WORKER_ID_BITS + DATA_CENTER_ID_BITS;
private final static long SEQUENCE_MASK = -1L ^ (-1L << SEQUENCE_BITS);
private long lastTimestamp = -1L;
private long sequence = 0L;
private final long workerId;
private final long dataCenterId;
private static volatile Snowflake snowflake = null;
private static Object lock = new Object();
//单例禁止new实例化
private Snowflake(long workerId, long dataCenterId) {
if (workerId > MAX_WORKER_ID || workerId < 0) {
workerId = getRandom();
}
if (dataCenterId > MAX_DATA_CENTER_ID || dataCenterId < 0) {
throw new IllegalArgumentException(String.format("%s 数据中心ID最大值必须是 %d 到 %d 之间", dataCenterId, 0, MAX_DATA_CENTER_ID));
}
this.workerId = workerId;
this.dataCenterId = dataCenterId;
}
/**
* 获取单列
*
* @return
*/
public static Snowflake getInstanceSnowflake() {
if (snowflake == null) {
synchronized (lock) {
long workerId ;
long dataCenterId = getRandom();
try {
//第一次使用获取mac地址的
workerId = getWorkerId();
} catch (Exception e) {
workerId = getRandom();
}
snowflake = new Snowflake(workerId, dataCenterId);
}
}
return snowflake;
}
/**
* 生成1-31之间的随机数
*
* @return
*/
private static long getRandom() {
int max = (int) (MAX_WORKER_ID);
int min = 1;
Random random = new Random();
long result = random.nextInt(max - min) + min;
return result;
}
public static String getSnowflakeId() throws Exception{
return Snowflake.getInstanceSnowflake().nextId()+"";
}
private synchronized long nextId() throws Exception {
long timestamp = time();
if (timestamp < lastTimestamp) {
throw new Exception("时钟向后移动，拒绝生成id " + (lastTimestamp - timestamp) + " milliseconds");
}
if (lastTimestamp == timestamp) {
// 当前毫秒内，则+1
sequence = (sequence + 1) & SEQUENCE_MASK;
if (sequence == 0) {
// 当前毫秒内计数满了，则等待下一秒
timestamp = tilNextMillis(lastTimestamp);
}
} else {
sequence = 0;
}
lastTimestamp = timestamp;
// ID偏移组合生成最终的ID，并返回ID
long nextId = ((timestamp - TWEPOCH) << TIMESTAMP_LEFT_SHIFT)
| (dataCenterId << DATA_CENTER_ID_SHIFT) | (workerId << WORKER_ID_SHIFT) | sequence;
return nextId;
}
private long tilNextMillis(final long lastTimestamp) {
long timestamp = this.time();
while (timestamp <= lastTimestamp) {
timestamp = this.time();
}
return timestamp;
}
private long time() {
return System.currentTimeMillis();
}
@SuppressWarnings("Duplicates")
private static long getWorkerId() throws SocketException, UnknownHostException, NullPointerException {
@SuppressWarnings("unused")
InetAddress ip = InetAddress.getLocalHost();
NetworkInterface network = null;
Enumeration<NetworkInterface> en = NetworkInterface.getNetworkInterfaces();
while (en.hasMoreElements()) {
NetworkInterface nint = en.nextElement();
if (!nint.isLoopback() && nint.getHardwareAddress() != null) {
network = nint;
break;
}
}
@SuppressWarnings("ConstantConditions")
byte[] mac = network.getHardwareAddress();
Random rnd = new Random();
byte rndByte = (byte) (rnd.nextInt() & 0x000000FF);
// 取mac地址最后一位和随机数
return ((0x000000FF & (long) mac[mac.length - 1]) | (0x0000FF00 & (((long) rndByte) << 8))) >> 6;
}
public static void main(String[] args) {
long start = System.currentTimeMillis();
try {
for (int i = 0, len = 1000000; i < len; i++) {
//getSnowflakeId();
System.out.println(getSnowflakeId());
}
} catch (Exception e) {
}
System.out.println("100万耗时: " + (System.currentTimeMillis()-start) + "ms");
}
}

复制代码

2. 实现接口重写方法

@Configuration
public class FlowableConfiguration implements EngineConfigurationConfigurer<SpringProcessEngineConfiguration>
{
@Override
public void configure(SpringProcessEngineConfiguration springProcessEngineConfiguration) {
springProcessEngineConfiguration.setIdGenerator(new IdGenerator() {
@Override
public String getNextId() {
try {
return Snowflake.getSnowflakeId(); //id生成方法
}catch (Exception e) {
}
return null;
}
});
}
}

复制代码

3. 完成