@Test
public void readBytes() {

    try {
        assertNull(FileUtil.readBytes((String) null));
        assertNull(FileUtil.readBytes((File) null));
        assertNull(FileUtil.readBytes("notexist"));
        assertNull(FileUtil.readBytes(new File("notexist")));
        assertNull(FileUtil.readBytes(ClassLoaderUtil.getClasspath()));
        String log4jPath = ClassLoaderUtil.getClasspath() + File.separator + "META-INF/log4j.properties";
        long fileSize = new File(log4jPath).length();
        assertEquals(fileSize, FileUtil.readBytes(log4jPath).length);
    } catch (IOException e) {
        e.printStackTrace();
    }
}