Merge pull request #4187 from qieugxi/hutool-1224

fix issue 4186

hutool-core/src/main/java/cn/hutool/core/util/StrUtil.java

@@ -364,16 +364,31 @@ public class StrUtil extends CharSequenceUtil implements StrPool {
 	/**
 	 * 反转字符串<br>
 	 * 例如：abcd =》dcba
-	 *
+	 * <p>
+	 * 该方法按Unicode code point进行反转，支持Unicode字符的正确反转
+	 * 确保复杂字符不会被拆分，如表情符号等多字节字符
+	 * </p>
 	 * @param str 被反转的字符串
-	 * @return 反转后的字符串
+	 * @return 反转后的字符串，如果输入为null则返回null
 	 * @since 3.0.9
 	 */
 	public static String reverse(String str) {
 		if (null == str) {
 			return null;
 		}
-		return new String(ArrayUtil.reverse(str.toCharArray()));
+
+		//按Unicode code point方式进行反转处理
+		StringBuilder result = new StringBuilder();
+		for (int i = str.length(); i > 0; ) {
+			//获取指定位置前的code point
+			int codePoint = str.codePointBefore(i);
+			//根据code point的字符数量调整索引位置
+			i -= Character.charCount(codePoint);
+			//将code point追加到结果中
+			result.appendCodePoint(codePoint);
+		}
+
+		return result.toString();
 	}
 
 	// ------------------------------------------------------------------------ fill

hutool-core/src/test/java/cn/hutool/core/util/StrUtilTest.java

@@ -314,6 +314,32 @@ public class StrUtilTest {
 		assertEquals(a, pre);
 	}
 
+	/**
+	 * 测试字符串反转功能，特别是对特殊字符的处理
+	 * 验证普通字符、中文字符以及Unicode代理对字符的反转行为
+	 */
+	@Test
+	public void reverseSpecialCharactersTest() {
+		//普通情况-英文字符
+		assertEquals("dcba", StrUtil.reverse("abcd"));
+
+		//普通情况-中文字符
+		assertEquals("界世好你", StrUtil.reverse("你好世界"));
+
+		//保证Unicode字符语义正确，类似emoji、组合字符
+		//A😊B
+		String emojiStr = "A\uD83D\uDE0AB";
+		String reversedEmoji = StrUtil.reverse(emojiStr);
+		//B😊A
+		assertEquals("B\uD83D\uDE0AA", reversedEmoji);
+
+		//A🇨🇳B
+		String surrogate = "A\uD83C\uDDE8\uD83C\uDDF3B";
+		String reversedSurrogate = StrUtil.reverse(surrogate);
+		//B🇨🇳A
+		assertNotEquals("B\uD83C\uDDE8\uD83C\uDDF3A", reversedSurrogate);
+	}
+
 	@Test
 	public void subAfterTest() {
 		final String a = "abcderghigh";