VK login using Kotlin/Java?

Question

Java

In this post (which, unfortunately, is already in 2012), the author managed to write a function that itself received an Access Token.
Now we need to do the same.
The function on Kotlin that is available (full analogue from the post):

//Здесь добавлено, дабы не было ошибки при работе с cookie
    val globalConfig = RequestConfig.custom().setCookieSpec(CookieSpecs.STANDARD).build()
    val httpClient = HttpClientBuilder.create().setDefaultRequestConfig(globalConfig).build()
    var post = HttpPost(
                    "http://oauth.vk.com/authorize?" +
                    "client_id=" + id +
                    "&scope=" + "wall,photos" +
                    "&redirect_uri=" + "https://oauth.vk.com/blank.html" +
                    "&display=" + "popup" +
                    "&response_type=" + "token"
    )
    var response = httpClient.execute(post)
    post.abort()

// Тут ошибка NullPointerException
    var headerLocation = response.getFirstHeader("location").value
    val uri = URI(headerLocation)

    val ip_h = uri.query.split("&")[2].split("=")[1]
    val to_h = uri.query.split("&")[4].split("=")[1]

    post = HttpPost(
                    "https://login.vk.com/?act=login&soft=1"+
                    "&q=1"+
                    "&ip_h="+ip_h+
                    "&from_host=oauth.vk.com"+
                    "&to="+to_h+
                    "&expire=0"+
                    "&email="+ login +
                    "&pass="+ pass
    )
    response = httpClient.execute(post)
    post.abort()
    headerLocation = response.getFirstHeader("location").value

    post = HttpPost(headerLocation)
    response = httpClient.execute(post)
    post.abort()

    headerLocation = response.getFirstHeader("location").value

    httpClient.close()

    return headerLocation.split("#")[1].split("&")[0].split("=")[1]

But the problem is that already after the first post request, there is no header Location in the response (I marked the place of the error with a comment), although if you copy the line and paste it into the browser, everything is fine.
Is it possible to get around this somehow?

Answer 1

There are already ready-made solutions like Spring Social VKontakte .