public static Map<String, Object> get(URL url, String token) throws IOException {
        HttpURLConnection conn = getURLConnection(url);
//        conn.setRequestProperty("Content-Type", APPLICATION_JSON);
        conn.setRequestMethod(HTTP_GET);
        conn.setDoInput(true);
//        conn.setDoOutput(true);
        if (token != null) {
            System.out.println(token);
            conn.setRequestProperty("X-Auth-Token", token);
        }
        System.out.println(conn.toString());

        if (conn.getResponseCode() == 401) {
            throw new IOException("Authorize Error occurs and the response code is :" + conn.getResponseCode() + ",and the message is:" + conn.getResponseMessage());
        }
        
        System.out.println(conn.getResponseCode());
        
        ObjectMapper mapper = new ObjectMapper();
        mapper.configure(DeserializationConfig.Feature.FAIL_ON_UNKNOWN_PROPERTIES, false);
        
//        System.out.println(mapper.readValue(conn.getInputStream(), new TypeReference<Map<String, Object>>() {}));
        
        return mapper.readValue(conn.getInputStream(), new TypeReference<Map<String, Object>>() {
        });
        

    }

    /**
     * Creates the HTTP URL connection
     * 
     * @param url
     *            the URL to be used to establish HTTP connection
     * @return A HttpURLConnection
     */
    private static HttpURLConnection getURLConnection(URL url) throws IOException {
        HttpURLConnection conn = (HttpURLConnection) url.openConnection();
        // disable cache
        conn.setUseCaches(false);
        // turn off HTTP keep-alive
        conn.setRequestProperty("Connection", "close");

        return conn;
    }

Exception in thread "main" java.io.FileNotFoundException: http://127.0.0.1:5000/v2/2835ba0b17384840941b5c5d653fb81a/servers/detail
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:525)
    at sun.net.www.protocol.http.HttpURLConnection$6.run(HttpURLConnection.java:1664)
    at sun.net.www.protocol.http.HttpURLConnection$6.run(HttpURLConnection.java:1662)
    at java.security.AccessController.doPrivileged(Native Method)
    at sun.net.www.protocol.http.HttpURLConnection.getChainedException(HttpURLConnection.java:1660)
    at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1243)
    at com.intel.cpa.openstack.HttpUtil.get(HttpUtil.java:148)
    at com.intel.cpa.openstack.NovaAPI.listServers(NovaAPI.java:46)
    at com.intel.cpa.openstack.NovaAPI.main(NovaAPI.java:37)
Caused by: java.io.FileNotFoundException: http://127.0.0.1:5000/v2/2835ba0b17384840941b5c5d653fb81a/servers/detail
    at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1613)
    at java.net.HttpURLConnection.getResponseCode(HttpURLConnection.java:468)
    at com.intel.cpa.openstack.HttpUtil.get(HttpUtil.java:137)
    ... 2 more