public static File file(String path) {
		if (null == path) {
			return null;
		}
		return new File(getAbsolutePath(path));
	}
@Test
	public void fileTest2() {
		assertThrows(IllegalArgumentException.class, () -> {
			final File file = FileUtil.file("d:/aaa", "bbb");
			assertNotNull(file);

			// 构建目录中出现非子目录抛出异常
			FileUtil.file(file, "../ccc");

			FileUtil.file("E:/");
		});
	}