public static Class loadClass(String className) {
        if (className.length() >= 192) {
            return null;
        }

        switch (className) {
            case "O":
            case "Object":
            case "java.lang.Object":
                return Object.class;
            case "java.util.Collections$EmptyMap":
                return Collections.emptyMap().getClass();
            case "java.util.Collections$EmptyList":
                return Collections.emptyList().getClass();
            case "java.util.Collections$EmptySet":
                return Collections.emptySet().getClass();
            case "java.util.Optional":
                return Optional.class;
            case "java.util.OptionalInt":
                return OptionalInt.class;
            case "java.util.OptionalLong":
                return OptionalLong.class;
            case "List":
            case "java.util.List":
                return List.class;
            case "A":
            case "ArrayList":
            case "java.util.ArrayList":
                return ArrayList.class;
            case "LA":
            case "LinkedList":
            case "java.util.LinkedList":
                return LinkedList.class;
            case "Map":
            case "java.util.Map":
                return Map.class;
            case "M":
            case "HashMap":
            case "java.util.HashMap":
                return HashMap.class;
            case "LM":
            case "LinkedHashMap":
            case "java.util.LinkedHashMap":
                return LinkedHashMap.class;
            case "ConcurrentHashMap":
                return ConcurrentHashMap.class;
            case "ConcurrentLinkedQueue":
                return ConcurrentLinkedQueue.class;
            case "ConcurrentLinkedDeque":
                return ConcurrentLinkedDeque.class;
            case "JSONObject":
                return JSONObject.class;
            case "JO1":
                className = "com.alibaba.fastjson.JSONObject";
                break;
            case "Set":
            case "java.util.Set":
                return Set.class;
            case "HashSet":
            case "java.util.HashSet":
                return HashSet.class;
            case "LinkedHashSet":
            case "java.util.LinkedHashSet":
                return LinkedHashSet.class;
            case "TreeSet":
            case "java.util.TreeSet":
                return TreeSet.class;
            case "java.lang.Class":
                return Class.class;
            case "java.lang.Integer":
                return Integer.class;
            case "java.lang.Long":
                return Long.class;
            case "String":
            case "java.lang.String":
                return String.class;
            case "[String":
                return String[].class;
            case "I":
            case "int":
                return int.class;
            case "S":
            case "short":
                return short.class;
            case "J":
            case "long":
                return long.class;
            case "Z":
            case "boolean":
                return boolean.class;
            case "B":
            case "byte":
                return byte.class;
            case "F":
            case "float":
                return float.class;
            case "D":
            case "double":
                return double.class;
            case "C":
            case "char":
                return char.class;
            case "[B":
            case "byte[]":
                return byte[].class;
            case "[S":
            case "short[]":
                return short[].class;
            case "[I":
            case "int[]":
                return int[].class;
            case "[J":
            case "long[]":
                return long[].class;
            case "[F":
            case "float[]":
                return float[].class;
            case "[D":
            case "double[]":
                return double[].class;
            case "[C":
            case "char[]":
                return char[].class;
            case "[Z":
            case "boolean[]":
                return boolean[].class;
            case "[O":
                return Object[].class;
            case "UUID":
                return UUID.class;
            case "Date":
                return Date.class;
            case "Calendar":
                return Calendar.class;
            case "java.io.IOException":
                return java.io.IOException.class;
            case "java.util.Collections$UnmodifiableRandomAccessList":
                return CLASS_UNMODIFIABLE_LIST;
            case "java.util.Arrays$ArrayList":
                return Arrays.asList(1).getClass();
            case "java.util.Collections$SingletonList":
                return CLASS_SINGLE_LIST;
            case "java.util.Collections$SingletonSet":
                return CLASS_SINGLE_SET;
            default:
                break;
        }

        Class mapping = TYPE_MAPPINGS.get(className);
        if (mapping != null) {
            return mapping;
        }

        if (className.startsWith("java.util.ImmutableCollections$")) {
            try {
                return Class.forName(className);
            } catch (ClassNotFoundException e) {
                return CLASS_UNMODIFIABLE_LIST;
            }
        }

        if (className.charAt(0) == 'L' && className.charAt(className.length() - 1) == ';') {
            className = className.substring(1, className.length() - 1);
        }

        if (className.charAt(0) == '[' || className.endsWith("[]")) {
            String itemClassName = className.charAt(0) == '[' ? className.substring(1) : className.substring(0, className.length() - 2);
            Class itemClass = loadClass(itemClassName);
            if (itemClass == null) {
                throw new JSONException("load class error " + className);
            }
            return Array.newInstance(itemClass, 0).getClass();
        }

        ClassLoader contextClassLoader = Thread.currentThread().getContextClassLoader();
        if (contextClassLoader != null) {
            try {
                return contextClassLoader.loadClass(className);
            } catch (ClassNotFoundException ignored) {
            }
        }

        try {
            return JSON.class.getClassLoader().loadClass(className);
        } catch (ClassNotFoundException ignored) {
        }

        try {
            return Class.forName(className);
        } catch (ClassNotFoundException ignored) {
        }

        return null;
    }
decimal is integer, check has non-zero small

@param decimal
@return
core/src/main/java/com/alibaba/fastjson2/util/TypeUtils.java