public static <T> Reference<T> create(ReferenceType type, T referent) {
		return create(type, referent, null);
	}
@Test
	public void createPhantomTest(){
		final Reference<Integer> integerReference = ReferenceUtil.create(ReferenceUtil.ReferenceType.PHANTOM, 1);
		assertTrue(integerReference instanceof PhantomReference);
		// get方法永远都返回null，PhantomReference只能用来监控对象的GC状况
		assertNull(integerReference.get());
	}