ID主键生成策略新增ULID算法

对比UUID，ULID更加简洁，更加安全，更加快速，最关键的事可排序。

mybatis-flex-core/src/main/java/com/mybatisflex/core/keygen/KeyGeneratorFactory.java

@@ -19,6 +19,7 @@ import com.mybatisflex.core.exception.FlexExceptions;
 import com.mybatisflex.core.exception.locale.LocalizedFormats;
 import com.mybatisflex.core.keygen.impl.FlexIDKeyGenerator;
 import com.mybatisflex.core.keygen.impl.SnowFlakeIDKeyGenerator;
+import com.mybatisflex.core.keygen.impl.ULIDKeyGenerator;
 import com.mybatisflex.core.keygen.impl.UUIDKeyGenerator;
 import com.mybatisflex.core.util.StringUtil;
 
@@ -39,6 +40,8 @@ public class KeyGeneratorFactory {
         register(KeyGenerators.uuid, new UUIDKeyGenerator());
         register(KeyGenerators.flexId, new FlexIDKeyGenerator());
         register(KeyGenerators.snowFlakeId, new SnowFlakeIDKeyGenerator());
+        register(KeyGenerators.ulid, new ULIDKeyGenerator());
+
     }
 
 

mybatis-flex-core/src/main/java/com/mybatisflex/core/keygen/KeyGenerators.java

@@ -38,4 +38,9 @@ public class KeyGenerators {
      */
     public static final String snowFlakeId = "snowFlakeId";
 
+    /**
+     * ulid 主键生成器
+     * {@link com.mybatisflex.core.keygen.impl.ULIDKeyGenerator}
+     */
+    public static final String ulid = "ulid";
 }

mybatis-flex-core/src/main/java/com/mybatisflex/core/keygen/impl/ULIDKeyGenerator.java

@@ -0,0 +1,120 @@
+/*
+ *  Copyright (c) 2022-2025, Mybatis-Flex (fuhai999@gmail.com).
+ *  <p>
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *  <p>
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *  <p>
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package com.mybatisflex.core.keygen.impl;
+
+import com.mybatisflex.core.keygen.IKeyGenerator;
+
+import java.util.concurrent.ThreadLocalRandom;
+
+/**
+ * ULID: 对比UUID的优势在于可排序性和性能。
+ * <p>
+ * 特点：
+ * 1、保证 id 生成的顺序为时间顺序，越往后生成的 ID 值越大；
+ * 2、可以按照生成的时间进行排序，而不需要全局协调；
+ * 3、生成速度快；
+ * <p>
+ * <p>参考：<a href="https://github.com/ulid/spec">Sequence</a>
+ */
+public class ULIDKeyGenerator implements IKeyGenerator {
+
+    private static final char[] ENCODING_CHARS = {
+        '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
+        'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'J', 'K',
+        'M', 'N', 'P', 'Q', 'R', 'S', 'T', 'V', 'W', 'X',
+        'Y', 'Z'
+    };
+
+    private static final long TIMESTAMP_OVERFLOW_MASK = 0xFFFF_0000_0000_0000L;
+
+    private static final ThreadLocal<StringBuilder> THREAD_LOCAL_BUILDER =
+        ThreadLocal.withInitial(() -> new StringBuilder(26));
+
+    private long lastTimestamp = 0;
+
+    private long lastRandom = 0;
+
+    @Override
+    public Object generate(Object entity, String keyColumn) {
+        return nextId();
+    }
+
+    /**
+     * 生成一个 ULID
+     *
+     * @return ULID
+     */
+    public String nextId() {
+        return generateULID(System.currentTimeMillis()).toLowerCase();
+    }
+
+    /**
+     * 生成一个严格单调的 ULID
+     *
+     * @return ULID
+     */
+    public synchronized String nextMonotonicId() {
+        long timestamp = System.currentTimeMillis();
+        if (timestamp > lastTimestamp) {
+            lastTimestamp = timestamp;
+            lastRandom = ThreadLocalRandom.current().nextLong();
+        } else {
+            lastRandom++;
+            if (lastRandom == 0) {
+                timestamp = waitNextMillis(lastTimestamp);
+                lastTimestamp = timestamp;
+                lastRandom = ThreadLocalRandom.current().nextLong();
+            }
+        }
+        return generateULID(lastTimestamp, lastRandom).toLowerCase();
+    }
+
+    private String generateULID(long timestamp) {
+        return generateULID(timestamp, ThreadLocalRandom.current().nextLong());
+    }
+
+    private String generateULID(long timestamp, long random) {
+        checkTimestamp(timestamp);
+        StringBuilder builder = THREAD_LOCAL_BUILDER.get();
+        builder.setLength(0);
+
+        appendCrockford(builder, timestamp, 10);
+        appendCrockford(builder, random, 16);
+
+        return builder.toString();
+    }
+
+    private long waitNextMillis(long lastTimestamp) {
+        long timestamp = System.currentTimeMillis();
+        while (timestamp <= lastTimestamp) {
+            timestamp = System.currentTimeMillis();
+        }
+        return timestamp;
+    }
+
+    private static void appendCrockford(StringBuilder builder, long value, int count) {
+        for (int i = (count - 1) * 5; i >= 0; i -= 5) {
+            int index = (int) ((value >>> i) & 0x1F);
+            builder.append(ENCODING_CHARS[index]);
+        }
+    }
+
+    private static void checkTimestamp(long timestamp) {
+        if ((timestamp & TIMESTAMP_OVERFLOW_MASK) != 0) {
+            throw new IllegalArgumentException("ULID does not support timestamps after +10889-08-02T05:31:50.655Z!");
+        }
+    }
+}

mybatis-flex-core/src/main/java/com/mybatisflex/core/row/RowKey.java

@@ -46,6 +46,11 @@ public class RowKey implements Serializable {
      */
     public static final RowKey SNOW_FLAKE_ID = RowKey.of("id", KeyType.Generator, KeyGenerators.snowFlakeId, true);
 
+    /**
+     * ulid
+     */
+    public static final RowKey ULID = RowKey.of("id", KeyType.Generator, KeyGenerators.ulid, true);
+
 
     public static RowKey of(String keyColumn) {
         SqlUtil.keepColumnSafely(keyColumn);

mybatis-flex-core/src/test/java/com/mybatisflex/coretest/IdGenTest.java

@@ -22,6 +22,7 @@ import com.mybatisflex.core.keygen.KeyGenerators;
 import org.junit.Assert;
 import org.junit.Test;
 
+import java.util.Arrays;
 import java.util.stream.LongStream;
 
 /**
@@ -54,4 +55,15 @@ public class IdGenTest {
         Assert.assertEquals(size, LongStream.of(ids).distinct().count());
     }
 
+    @Test
+    public void ULID() {
+        int size = 100_0000;
+        String[] ids = new String[size];
+        IKeyGenerator keyGenerator = KeyGeneratorFactory.getKeyGenerator(KeyGenerators.ulid);
+        for (int i = 0; i < size; i++) {
+            ids[i] = (String) keyGenerator.generate(null, null);
+        }
+        long distinctCount = Arrays.stream(ids).distinct().count();
+        Assert.assertEquals(size, distinctCount);
+    }
 }