code: @SuppressWarnings({ "rawtypes", "unchecked" })
  	protected Map<String, Object> getAddressCache() {
  		try {
  			final Field cacheField = InetAddress.class.getDeclaredField("addressCache");
  			cacheField.setAccessible(true);
  			final Object addressCache = cacheField.get(InetAddress.class);
  
  			Class clazz = addressCache.getClass();
  			final Field cacheMapField = clazz.getDeclaredField("cache");
  			cacheMapField.setAccessible(true);
  			return (Map) cacheMapField.get(addressCache);
  		}
  		catch (Exception e) {
  			throw new RuntimeException(e.getMessage(), e);
  		}
  	}
docs: 大约10年失效