一、
您有么有一种办法来代替UUID，就是说保证全球无重复！
Ps：不用说用 时间 + 随机字符，就是这么说的，技术说那也可能有重复的！
不用说 Base64或Base58，这个也是基于UUID的
现在说的是你自己创造的"UUID"
二、
Oracle中有Sequence，那么您如何在不用Sequence的情况下，做出类似Sequence的效果呢？比方说我当前的最大Id是5，那么下一个应该就是6，但是我1秒可能有上百万的数据存入，您如何实现呢

一、除了你说的2种我想不出来，坐等答案。
二、可以自己写Sequence生成器。

我项目中用的：
import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; import java.sql.Statement; import java.util.HashMap; import java.util.Map;   /** * * <b>Note</b>: Java实现的Sequence工具 */public class SequenceUtil {                   /**          * 单例模式          */        private static SequenceUtil instance = new SequenceUtil();                   /**          * 存放序列的MAP          */        private Map<String, KeyInfo> keyMap = new HashMap<String, KeyInfo>(20);         private static final int POOL_SIZE = 1;           /**          * 防止外部实例化          */        private SequenceUtil() {         }           /**          * 单例模式,获取单例          *          * @return SequenceUtils的单例对象          */        public static SequenceUtil getInstance() {                 return instance;         }           /**          * 获取下一个sequence值          *          * @param keyName          * Sequence名称          * @return 下一个Sequence键值          */        public synchronized int getNextKeyValue(String keyName) {                 KeyInfo keyInfo = null;                 Integer keyObject = null;                 try {                         if (keyMap.containsKey(keyName)) {                                 keyInfo = keyMap.get(keyName);                         } else {                                 keyInfo = new KeyInfo(keyName, POOL_SIZE);                                 keyMap.put(keyName, keyInfo);                         }                         keyObject = keyInfo.getNextKey();                 } catch (SQLException e) {                         e.printStackTrace();                 }                 return keyObject;         } }   class KeyInfo {                   /**          * 当前Sequence载体的最大值          */        private int maxKey;                   /**          * 当前Sequence的最小值          */        private int minKey;                   /**          * 下一个Sequence值          */        private int nextKey;                   /**          * Sequence缓存值          */        private int poolSize;                   /**          * Sequence的名称          */        private String keyName;                   /**          * 更新存放Sequence表的语句          */        private static final String sql_update = "UPDATE intpub_Sequence SET KEYVALUE = KEYVALUE + ? WHERE KEYNAME = ?";                   /**          * 查询Sequence表中的当前值          */        private static final String sql_query = "SELECT KEYVALUE FROM intpub_Sequence WHERE KEYNAME = ?";           public KeyInfo(String keyName, int poolSize) throws SQLException {                 this.poolSize = poolSize;                 this.keyName = keyName;                 retrieveFromDB();         }           public String getKeyName() {                 return keyName;         }           public int getMaxKey() {                 return maxKey;         }           public int getMinKey() {                 return minKey;         }           public int getPoolSize() {                 return poolSize;         }           /**          * 获取下一个Sequence值          *          * @return 下一个Sequence值          * @throws SQLException          */        public synchronized int getNextKey() throws SQLException {                 if (nextKey > maxKey) {                         retrieveFromDB();                 }                 return nextKey++;         }           /**          * 执行Sequence表初始化和更新工作          *          * @throws SQLException          */        private void retrieveFromDB() throws SQLException {                   Connection conn = ConnectionPool.getInstance().getConnection();                 // 查询数据库                 PreparedStatement pstmt_query = conn.prepareStatement(sql_query);                 pstmt_query.setString(1, keyName);                 ResultSet rs = pstmt_query.executeQuery();                 if (rs.next()) {                         maxKey = rs.getInt(1) + poolSize;                         minKey = maxKey - poolSize + 1;                         nextKey = minKey;                         rs.close();                         pstmt_query.close();                 } else {                         String init_sql = "INSERT INTO intpub_Sequence(KEYNAME,KEYVALUE) VALUES('"                                        + keyName + "',10000 + " + poolSize + ")";                         Statement stmt = conn.createStatement();                         stmt.executeUpdate(init_sql);                         maxKey = 10000 + poolSize;                         minKey = maxKey - poolSize + 1;                         nextKey = minKey;                         stmt.close();                         return;                 }                   // 更新数据库                 conn.setAutoCommit(false);                 PreparedStatement pstmt_up = conn.prepareStatement(sql_update);                 pstmt_up.setLong(1, poolSize);                 pstmt_up.setString(2, keyName);                 pstmt_up.executeUpdate();                 pstmt_up.close();                 conn.commit();                   rs.close();                 pstmt_query.close();                 conn.close();         }   }