Java雪花算法生产成ID

偏执的太偏执、 2022-12-11 04:22 123阅读 0赞

import org.springframework.stereotype.Component;
    
    import java.lang.management.ManagementFactory;
    import java.lang.management.RuntimeMXBean;
    import java.net.NetworkInterface;
    import java.net.SocketException;
    import java.util.Enumeration;
    
    @Component
    public class SnowFlakeId { 
    
        //设置时间初始值
        private final  long twepoch = 12888349746579L;
        // 机器标识位数
        private final  long workerIdBits = 5L;
        // 数据中心标识位数
        private final  long datacenterIdBits = 5L;
    
        // 毫秒内自增位数
        private final  long sequenceBits = 12L;
        // 机器ID偏左移12位
        private final  long workerIdShift = sequenceBits;
        // 数据中心ID左移17位
        private final  long datacenterIdShift = sequenceBits + workerIdBits;
        // 时间毫秒左移22位
        private final  long timestampLeftShift = sequenceBits + workerIdBits + datacenterIdBits;
        //sequence掩码，确保sequnce不会超出上限
        private final  long sequenceMask = -1L ^ (-1L << sequenceBits);
        //上次时间戳
        private  long lastTimestamp = -1L;
        //序列
        private long sequence = 0L;
        //服务器ID
        private long workerId = 1L;
        private  long workerMask = -1L ^ (-1L << workerIdBits);
        //进程编码
        private long processId = 1L;
        private  long processMask = -1L ^ (-1L << datacenterIdBits);
    
        private static SnowFlakeId snowFlakeId = null;
    
        static { 
            snowFlakeId = new SnowFlakeId();
        }
    
        public  synchronized long nextId() { 
            return snowFlakeId.getNextId();
        }
    
        private SnowFlakeId() { 
    
            //获取机器编码
            this.workerId = this.getMachineNum();
            //获取进程编码
            RuntimeMXBean runtimeMXBean = ManagementFactory.getRuntimeMXBean();
            this.processId = Long.valueOf(runtimeMXBean.getName().split("@")[0]).longValue();
    
            //避免编码超出最大值
            this.workerId = workerId & workerMask;
            this.processId = processId & processMask;
        }
    
        public synchronized long getNextId() { 
            //获取时间戳
            long timestamp = timeGen();
            //如果时间戳小于上次时间戳则报错
            if (timestamp < lastTimestamp) { 
                try { 
                    throw new Exception("Clock moved backwards. Refusing to generate id for " + (lastTimestamp - timestamp) + " milliseconds");
                } catch (Exception e) { 
                    e.printStackTrace();
                }
            }
            //如果时间戳与上次时间戳相同
            if (lastTimestamp == timestamp) { 
                // 当前毫秒内，则+1，与sequenceMask确保sequence不会超出上限
                sequence = (sequence + 1) & sequenceMask;
                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) << timestampLeftShift) | (processId << datacenterIdShift) | (workerId << workerIdShift) | sequence;
            return nextId;
        }
    
        /** * 再次获取时间戳直到获取的时间戳与现有的不同 * * @param lastTimestamp * @return 下一个时间戳 */
        private long tilNextMillis(final long lastTimestamp) { 
            long timestamp = this.timeGen();
            while (timestamp <= lastTimestamp) { 
                timestamp = this.timeGen();
            }
            return timestamp;
        }
    
        private long timeGen() { 
            return System.currentTimeMillis();
        }
    
        /** * 获取机器编码 * * @return */
        private long getMachineNum() { 
            long machinePiece;
            StringBuilder sb = new StringBuilder();
            Enumeration<NetworkInterface> e = null;
            try { 
                e = NetworkInterface.getNetworkInterfaces();
            } catch (SocketException e1) { 
                e1.printStackTrace();
            }
            while (e.hasMoreElements()) { 
                NetworkInterface ni = e.nextElement();
                sb.append(ni.toString());
            }
            machinePiece = sb.toString().hashCode();
            return machinePiece;
        }
    
    }

测试

import org.junit.Test;
    import org.junit.runner.RunWith;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.boot.test.context.SpringBootTest;
    import org.springframework.test.context.junit4.SpringRunner;
    import java.util.ArrayList;
    import java.util.List;
    import java.util.concurrent.Callable;
    import java.util.concurrent.ExecutorService;
    import java.util.concurrent.Executors;
    import java.util.concurrent.TimeUnit;
    
    @RunWith(SpringRunner.class)
    @SpringBootTest
    public class SnowFlakeIdTest { 
    
        @Autowired
        SnowFlakeId snowFlakeId;
    
        //测试生成140万个ID，需要多长时间，测试10次(10*140万)
        @Test
        public void nextId() { 
    
            long avg = 0;
            for (int k = 0; k < 10; k++) { 
                List<Callable<Long>> partitions = new ArrayList<Callable<Long>>();
              // final IdGen idGen = IdGen.get();
                for (int i = 0; i < 1400000; i++) { 
                    partitions.add(new Callable<Long>() { 
                        @Override
                        public Long call() throws Exception { 
                            return snowFlakeId.nextId();
                        }
                    });
                }
                ExecutorService executorPool = Executors.newFixedThreadPool(Runtime.getRuntime().availableProcessors());
                try { 
                    long s = System.currentTimeMillis();
                    executorPool.invokeAll(partitions, 10000, TimeUnit.SECONDS);
                    long s_avg = System.currentTimeMillis() - s;
                    avg += s_avg;
                    System.out.println("完成时间需要: " + s_avg / 1.0e3 + "秒");
                    executorPool.shutdown();
                } catch (Exception e) { 
                    e.printStackTrace();
                }
            }
            System.out.println("平均完成时间需要: " + avg / 10 / 1.0e3 + "秒");
    
        }
    
        @Test
        public void getNextId() { 
            System.out.println("============================");
    
            System.out.println( snowFlakeId);
            System.out.println("============================");
        }
    }

[全局唯一ID生成器浅析][ID]

[雪花算法（snowflake）自增ID][snowflake_ID]

[ID号生成 雪花算法][ID_]

[ID]: http://www.blogjava.net/bolo/archive/2015/07/13/426200.html
[snowflake_ID]: https://blog.csdn.net/nsxqf/article/details/85850232?utm_medium=distribute.pc_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-1.channel_param&depth_1-utm_source=distribute.pc_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-1.channel_param
[ID_]: https://www.jianshu.com/p/d3881a6a895e