修复HexUtil.format在处理长度小于2的字符串会抛异常，在处理长度为奇数的字符串时最后一个字符会被忽略的问题 修复SplitIter.computeNext递归调用可能导致栈溢出风险

hutool-core/src/main/java/cn/hutool/v7/core/codec/binary/HexUtil.java

@@ -16,7 +16,6 @@
 
 package cn.hutool.v7.core.codec.binary;
 
-import cn.hutool.v7.core.text.CharUtil;
 import cn.hutool.v7.core.text.StrUtil;
 
 import java.awt.Color;
@@ -249,16 +248,42 @@ public class HexUtil extends Hex {
 	 * @param prefix 自定义前缀，如0x
 	 * @return 格式化后的字符串
 	 */
-	public static String format(final String hexStr, String prefix) {
+	public static String format(final String hexStr, final String prefix) {
+		return format(hexStr, prefix, StrUtil.SPACE);
+	}
+
+	/**
+	 * 格式化Hex字符串，结果为每2位加一个空格，类似于：
+	 * <pre>
+	 *     e8 8c 67 03 80 cb 22 00 95 26 8f
+	 * </pre>
+	 *
+	 * @param hexStr    Hex字符串
+	 * @param prefix    自定义前缀，如0x
+	 * @param separator 自定义分隔符，如空格
+	 * @return 格式化后的字符串
+	 */
+	public static String format(final String hexStr, String prefix, String separator) {
+		if (StrUtil.isEmpty(hexStr)) {
+			return StrUtil.EMPTY;
+		}
 		if (null == prefix) {
 			prefix = StrUtil.EMPTY;
 		}
+		if (null == separator) {
+			separator = StrUtil.SPACE;
+		}
 
 		final int length = hexStr.length();
 		final StringBuilder builder = StrUtil.builder(length + length / 2 + (length / 2 * prefix.length()));
-		builder.append(prefix).append(hexStr.charAt(0)).append(hexStr.charAt(1));
+		for (int i = 0; i < length; i++) {
-		for (int i = 2; i < length - 1; i += 2) {
+			if (i % 2 == 0) {
-			builder.append(CharUtil.SPACE).append(prefix).append(hexStr.charAt(i)).append(hexStr.charAt(i + 1));
+				if (i != 0) {
+					builder.append(separator);
+				}
+				builder.append(prefix);
+			}
+			builder.append(hexStr.charAt(i));
 		}
 		return builder.toString();
 	}

hutool-core/src/main/java/cn/hutool/v7/core/text/split/SplitIter.java

@@ -89,29 +89,28 @@ public class SplitIter extends ComputeIter<String> implements Serializable {
 			return text.substring(offset);
 		}
 
-		final int start = finder.start(offset);
+		String result;
-		// 无分隔符，结束
+		int start;
-		if (start < 0) {
+		do {
-			// 如果不再有分隔符，但是遗留了字符，则单独作为一个段
+			start = finder.start(offset);
-			if (offset <= text.length()) {
+			// 无分隔符，结束
-				final String result = text.substring(offset);
+			if (start < 0) {
-				if (!ignoreEmpty || !result.isEmpty()) {
+				// 如果不再有分隔符，但是遗留了字符，则单独作为一个段
-					// 返回非空串
+				if (offset <= text.length()) {
-					offset = Integer.MAX_VALUE;
+					result = text.substring(offset);
-					return result;
+					if (!ignoreEmpty || !result.isEmpty()) {
+						// 返回非空串
+						offset = Integer.MAX_VALUE;
+						return result;
+					}
 				}
+				return null;
 			}
-			return null;
-		}
 
-		// 找到新的分隔符位置
+			// 找到新的分隔符位置
-		final String result = text.substring(offset, start);
+			result = text.substring(offset, start);
-		offset = finder.end(start);
+			offset = finder.end(start);
-
+		} while (ignoreEmpty && result.isEmpty()); // 空串则继续循环
-		if (ignoreEmpty && result.isEmpty()) {
-			// 发现空串且需要忽略时，跳过之
-			return computeNext();
-		}
 
 		count++;
 		return result;

hutool-core/src/test/java/cn/hutool/v7/core/text/split/SplitIterTest.java

@@ -23,9 +23,12 @@ import cn.hutool.v7.core.text.finder.StrFinder;
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
 
+import java.util.Collections;
 import java.util.List;
 import java.util.regex.Pattern;
 
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
 public class SplitIterTest {
 
 	@Test
@@ -38,7 +41,7 @@ public class SplitIterTest {
 				Integer.MAX_VALUE,
 				false
 		);
-		Assertions.assertEquals(6, splitIter.toList(false).size());
+		assertEquals(6, splitIter.toList(false).size());
 	}
 
 	@Test
@@ -51,7 +54,7 @@ public class SplitIterTest {
 				Integer.MAX_VALUE,
 				false
 		);
-		Assertions.assertEquals(4, splitIter.toList(false).size());
+		assertEquals(4, splitIter.toList(false).size());
 	}
 
 	@Test
@@ -65,7 +68,7 @@ public class SplitIterTest {
 		);
 
 		final List<String> strings = splitIter.toList(false);
-		Assertions.assertEquals(4, strings.size());
+		assertEquals(4, strings.size());
 	}
 
 	@Test
@@ -79,10 +82,10 @@ public class SplitIterTest {
 		);
 
 		final List<String> strings = splitIter.toList(true);
-		Assertions.assertEquals(3, strings.size());
+		assertEquals(3, strings.size());
-		Assertions.assertEquals("a", strings.get(0));
+		assertEquals("a", strings.get(0));
-		Assertions.assertEquals("efedsfs", strings.get(1));
+		assertEquals("efedsfs", strings.get(1));
-		Assertions.assertEquals("ddf", strings.get(2));
+		assertEquals("ddf", strings.get(2));
 	}
 
 	@Test
@@ -96,7 +99,7 @@ public class SplitIterTest {
 		);
 
 		final List<String> strings = splitIter.toList(false);
-		Assertions.assertEquals(3, strings.size());
+		assertEquals(3, strings.size());
 	}
 
 	@Test
@@ -110,7 +113,7 @@ public class SplitIterTest {
 		);
 
 		final List<String> strings = splitIter.toList(false);
-		Assertions.assertEquals(3, strings.size());
+		assertEquals(3, strings.size());
 	}
 
 	@Test
@@ -123,7 +126,7 @@ public class SplitIterTest {
 		);
 
 		final List<String> strings = splitIter.toList(false);
-		Assertions.assertEquals(4, strings.size());
+		assertEquals(4, strings.size());
 	}
 
 	@Test
@@ -136,7 +139,7 @@ public class SplitIterTest {
 		);
 
 		final List<String> strings = splitIter.toList(false);
-		Assertions.assertEquals(3, strings.size());
+		assertEquals(3, strings.size());
 	}
 
 	@Test
@@ -149,7 +152,7 @@ public class SplitIterTest {
 		);
 
 		final List<String> strings = splitIter.toList(false);
-		Assertions.assertEquals(1, strings.size());
+		assertEquals(1, strings.size());
 	}
 
 	// 切割字符串是空字符串时报错
@@ -164,7 +167,21 @@ public class SplitIterTest {
 			);
 
 			final List<String> strings = splitIter.toList(false);
-			Assertions.assertEquals(1, strings.size());
+			assertEquals(1, strings.size());
 		});
 	}
+
+	@Test
+	public void issue4169Test() {
+		final StringBuilder sb = new StringBuilder();
+		for (int i = 0; i < 20000; i++) { // 1万次连续分隔符，模拟递归深度风险场景
+			sb.append(",");
+		}
+		sb.append("test");
+
+		final SplitIter iter = new SplitIter(sb.toString(), new StrFinder(",",false), 0, true);
+		final List<String> result = iter.toList(false);
+
+		assertEquals(Collections.singletonList("test"), result);
+	}
 }

hutool-core/src/test/java/cn/hutool/v7/core/util/HexUtilTest.java

@@ -135,4 +135,34 @@ public class HexUtilTest {
 		final String hex3 = "#FF";
 		assertEquals(new BigInteger("FF", 16), HexUtil.toBigInteger(hex3));
 	}
+
+	@Test
+	public void testFormatEmpty() {
+		final String result = HexUtil.format("");
+		assertEquals("", result);
+	}
+
+	@Test
+	public void testFormatSingleChar() {
+		final String result = HexUtil.format("1");
+		assertEquals("1", result);
+	}
+
+	@Test
+	public void testFormatOddLength() {
+		final String result = HexUtil.format("123");
+		assertEquals("12 3", result);
+	}
+
+	@Test
+	public void testFormatWithPrefixSingleChar() {
+		final String result = HexUtil.format("1", "0x");
+		assertEquals("0x1", result);
+	}
+
+	@Test
+	public void testFormatWithPrefixOddLength() {
+		final String result = HexUtil.format("123", "0x");
+		assertEquals("0x12 0x3", result);
+	}
 }