public static Object getFieldValue(Object obj, String fieldName) {
        if (null == obj || StringUtil.isBlank(fieldName)) {
            return null;
        }
        Field field = getField(obj instanceof Class ? (Class<?>) obj : obj.getClass(), fieldName);
        return getFieldValue(obj, field);
    }
@Test
    public void getFieldValueTest() {
        TestSubClass testSubClass = new TestSubClass();
        Object privateField = ReflectUtil.getFieldValue(testSubClass, "privateField");
        Assert.assertEquals("privateField", privateField);

        Object field = ReflectUtil.getFieldValue(testSubClass, "field");
        Assert.assertEquals("field", field);

    }