!438 加入集合索引环形获取工具类RingIndexUtil

Merge pull request !438 from ZhouChuGang/v5-dev

hutool-core/src/main/java/cn/hutool/core/collection/RingIndexUtil.java

@@ -0,0 +1,100 @@
+package cn.hutool.core.collection;
+
+import cn.hutool.core.lang.Assert;
+
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.atomic.AtomicLong;
+
+/**
+ * 集合索引环形获取工具类
+ *
+ * @author ZhouChuGang
+ * @since 5.7.15
+ */
+public class RingIndexUtil {
+
+	/**
+	 * 通过cas操作 实现对指定值内的回环累加
+	 *
+	 * @param object     集合
+	 *                   <ul>
+	 *                   <li>Collection - the collection size
+	 *                   <li>Map - the map size
+	 *                   <li>Array - the array size
+	 *                   <li>Iterator - the number of elements remaining in the iterator
+	 *                   <li>Enumeration - the number of elements remaining in the enumeration
+	 *                   </ul>
+	 * @param atomicLong 原子操作类
+	 * @return 索引位置
+	 */
+	public static long ringNextLongByObj(Object object, AtomicLong atomicLong) {
+		Assert.notNull(object);
+		int modulo = CollUtil.size(object);
+		return ringNextLong(modulo, atomicLong);
+	}
+
+	/**
+	 * 通过cas操作 实现对指定值内的回环累加
+	 *
+	 * @param object        集合
+	 *                      <ul>
+	 *                      <li>Collection - the collection size
+	 *                      <li>Map - the map size
+	 *                      <li>Array - the array size
+	 *                      <li>Iterator - the number of elements remaining in the iterator
+	 *                      <li>Enumeration - the number of elements remaining in the enumeration
+	 *                      </ul>
+	 * @param atomicInteger 原子操作类
+	 * @return 索引位置
+	 */
+	public static int ringNextIntByObj(Object object, AtomicInteger atomicInteger) {
+		Assert.notNull(object);
+		int modulo = CollUtil.size(object);
+		return ringNextInt(modulo, atomicInteger);
+	}
+
+	/**
+	 * 通过cas操作 实现对指定值内的回环累加
+	 *
+	 * @param modulo        回环周期值
+	 * @param atomicInteger 原子操作类
+	 * @return 索引位置
+	 */
+	public static int ringNextInt(int modulo, AtomicInteger atomicInteger) {
+		Assert.notNull(atomicInteger);
+		Assert.isTrue(modulo > 0);
+		if (modulo == 1) {
+			return 0;
+		}
+		for (; ; ) {
+			int current = atomicInteger.get();
+			int next = (current + 1) % modulo;
+			if (atomicInteger.compareAndSet(current, next)) {
+				return next;
+			}
+		}
+	}
+
+	/**
+	 * 通过cas操作 实现对指定值内的回环累加
+	 *
+	 * @param modulo     回环周期值
+	 * @param atomicLong 原子操作类
+	 * @return 索引位置
+	 */
+	public static long ringNextLong(long modulo, AtomicLong atomicLong) {
+		Assert.notNull(atomicLong);
+		Assert.isTrue(modulo > 0);
+		if (modulo == 1) {
+			return 0;
+		}
+		for (; ; ) {
+			long current = atomicLong.get();
+			long next = (current + 1) % modulo;
+			if (atomicLong.compareAndSet(current, next)) {
+				return next;
+			}
+		}
+	}
+
+}

hutool-core/src/test/java/cn/hutool/core/collection/RingIndexUtilTest.java

@@ -0,0 +1,51 @@
+package cn.hutool.core.collection;
+
+import cn.hutool.core.thread.ThreadUtil;
+import org.junit.Test;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.atomic.AtomicLong;
+
+/**
+ * 集合索引环形获取工具类测试类
+ *
+ * @author ZhouChuGang
+ * @version 1.0
+ * @project hutool
+ * @date 2021/10/13 18:47
+ */
+public class RingIndexUtilTest {
+
+	private final List<String> strList = Arrays.asList("0", "1", "2", "3", "4", "5", "6", "7", "8", "9");
+
+	/**
+	 * 观察输出的打印为不重复的
+	 */
+	@Test
+	public void ringNextLongByObjTest() {
+		final AtomicLong atomicLong = new AtomicLong();
+		// 开启并发测试，每个线程获取到的元素都是唯一的
+		ThreadUtil.concurrencyTest(strList.size(), () -> {
+			final long index = RingIndexUtil.ringNextLongByObj(strList, atomicLong);
+			final String s = strList.get((int) index);
+			System.out.println(s);
+		});
+	}
+
+	/**
+	 * 观察输出的打印为不重复的
+	 */
+	@Test
+	public void ringNextIntByObjTest() {
+		final AtomicInteger atomicInteger = new AtomicInteger();
+		// 开启并发测试，每个线程获取到的元素都是唯一的
+		ThreadUtil.concurrencyTest(strList.size(), () -> {
+			final int index = RingIndexUtil.ringNextIntByObj(strList, atomicInteger);
+			final String s = strList.get(index);
+			System.out.println(s);
+		});
+	}
+
+}