fix 3506

hutool-json/src/main/java/cn/hutool/json/JSONUtil.java

@@ -796,6 +796,11 @@ public class JSONUtil {
 				return object.toString();
 			}
 
+			// Class类型保存类名
+			if (object instanceof Class<?>) {
+				return ((Class<?>) object).getName();
+			}
+
 			// Java内部类不做转换
 			if (ClassUtil.isJdkClass(object.getClass())) {
 				return object.toString();

hutool-json/src/test/java/cn/hutool/json/Issue3506Test.java

@@ -0,0 +1,30 @@
+package cn.hutool.json;
+
+import lombok.Data;
+import org.junit.Test;
+
+/**
+ * https://github.com/dromara/hutool/issues/3506
+ */
+public class Issue3506Test {
+
+	@Test
+	public void test3506() {
+		Languages languages = new Languages();
+		languages.setLanguageType(Java.class);
+		String hutoolJSONString = JSONUtil.toJsonStr(languages);
+		System.out.println(hutoolJSONString);
+		System.out.println(JSONUtil.toBean(hutoolJSONString, Languages.class));
+	}
+
+	@Data
+	public static class Languages {
+		private Class<? extends Language> languageType;
+	}
+
+	public interface Language {
+	}
+
+	public static class Java implements Language {
+	}
+}