Flowable实战Flowable6.4.1自定义id生成

Posted 2023-03-04 JEECG官方博客

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");

    

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;
            
        );
    

3. 完成