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Dahua ICC Open API SDK for Java
There is a newer version: 1.0.13.7
package com.dahuatech.hutool.core.lang;

import com.dahuatech.hutool.core.date.DateUtil;
import com.dahuatech.hutool.core.util.ClassLoaderUtil;
import com.dahuatech.hutool.core.util.RandomUtil;
import com.dahuatech.hutool.core.util.StrUtil;

import java.lang.management.ManagementFactory;
import java.net.NetworkInterface;
import java.nio.ByteBuffer;
import java.util.Enumeration;
import java.util.concurrent.atomic.AtomicInteger;

/**
 * MongoDB ID生成策略实现

 * ObjectId由以下几部分组成：
 *
 *  * 1. Time 时间戳。
 * 2. Machine 所在主机的唯一标识符，一般是机器主机名的散列值。
 * 3. PID 进程ID。确保同一机器中不冲突
 * 4. INC 自增计数器。确保同一秒内产生objectId的唯一性。
 * 
 *
 * 参考：http://blog.csdn.net/qxc1281/article/details/54021882
 *
 * @author looly
 * @since 4.0.0
 */
public class ObjectId {

  /** 线程安全的下一个随机数,每次生成自增+1 */
  private static final AtomicInteger nextInc = new AtomicInteger(RandomUtil.randomInt());
  /** 机器信息 */
  private static final int machine = getMachinePiece() | getProcessPiece();

  /**
   * 给定的字符串是否为有效的ObjectId
   *
   * @param s 字符串
   * @return 是否为有效的ObjectId
   */
  public static boolean isValid(String s) {
    if (s == null) {
      return false;
    }
    s = StrUtil.removeAll(s, "-");
    final int len = s.length();
    if (len != 24) {
      return false;
    }

    char c;
    for (int i = 0; i < len; i++) {
      c = s.charAt(i);
      if (c >= '0' && c <= '9') {
        continue;
      }
      if (c >= 'a' && c <= 'f') {
        continue;
      }
      if (c >= 'A' && c <= 'F') {
        continue;
      }
      return false;
    }
    return true;
  }

  /**
   * 获取一个objectId的bytes表现形式
   *
   * @return objectId
   * @since 4.1.15
   */
  public static byte[] nextBytes() {
    final ByteBuffer bb = ByteBuffer.wrap(new byte[12]);
    bb.putInt((int) DateUtil.currentSeconds()); // 4位
    bb.putInt(machine); // 4位
    bb.putInt(nextInc.getAndIncrement()); // 4位

    return bb.array();
  }

  /**
   * 获取一个objectId用下划线分割
   *
   * @return objectId
   */
  public static String next() {
    return next(false);
  }

  /**
   * 获取一个objectId
   *
   * @param withHyphen 是否包含分隔符
   * @return objectId
   */
  public static String next(boolean withHyphen) {
    byte[] array = nextBytes();
    final StringBuilder buf = new StringBuilder(withHyphen ? 26 : 24);
    int t;
    for (int i = 0; i < array.length; i++) {
      if (withHyphen && i % 4 == 0 && i != 0) {
        buf.append("-");
      }
      t = array[i] & 0xff;
      if (t < 16) {
        buf.append('0');
      }
      buf.append(Integer.toHexString(t));
    }
    return buf.toString();
  }

  // -----------------------------------------------------------------------------------------
  // Private method start
  /**
   * 获取机器码片段
   *
   * @return 机器码片段
   */
  private static int getMachinePiece() {
    // 机器码
    int machinePiece;
    try {
      StringBuilder netSb = new StringBuilder();
      // 返回机器所有的网络接口
      Enumeration e = NetworkInterface.getNetworkInterfaces();
      // 遍历网络接口
      while (e.hasMoreElements()) {
        NetworkInterface ni = e.nextElement();
        // 网络接口信息
        netSb.append(ni.toString());
      }
      // 保留后两位
      machinePiece = netSb.toString().hashCode() << 16;
    } catch (Throwable e) {
      // 出问题随机生成,保留后两位
      machinePiece = (RandomUtil.randomInt()) << 16;
    }
    return machinePiece;
  }

  /**
   * 获取进程码片段
   *
   * @return 进程码片段
   */
  private static int getProcessPiece() {
    // 进程码
    // 因为静态变量类加载可能相同,所以要获取进程ID + 加载对象的ID值
    final int processPiece;
    // 进程ID初始化
    int processId;
    try {
      // 获取进程ID
      final String processName = ManagementFactory.getRuntimeMXBean().getName();
      final int atIndex = processName.indexOf('@');
      if (atIndex > 0) {
        processId = Integer.parseInt(processName.substring(0, atIndex));
      } else {
        processId = processName.hashCode();
      }
    } catch (Throwable t) {
      processId = RandomUtil.randomInt();
    }

    final ClassLoader loader = ClassLoaderUtil.getClassLoader();
    // 返回对象哈希码,无论是否重写hashCode方法
    int loaderId = (loader != null) ? System.identityHashCode(loader) : 0;

    // 进程ID + 对象加载ID
    StringBuilder processSb = new StringBuilder();
    processSb.append(Integer.toHexString(processId));
    processSb.append(Integer.toHexString(loaderId));
    // 保留前2位
    processPiece = processSb.toString().hashCode() & 0xFFFF;

    return processPiece;
  }
  // -----------------------------------------------------------------------------------------
  // Private method end
}