Apache HttpClient библиотека реализующая набор функций для работы по протоколу HTTP.

Maven:

<dependency>
    <groupId>org.apache.httpcomponents</groupId>
    <artifactId>httpclient</artifactId>
    <version>4.5</version>
</dependency>

GET:

CloseableHttpClient httpclient = HttpClients.createDefault();
HttpGet httpGet = new HttpGet("http://sarjsheff.ru/");
CloseableHttpResponse response = httpclient.execute(httpGet);
try {
    System.out.println(response.getStatusLine());
    response.getEntity().writeTo(System.out);
} finally {
    try {
       response.close();
    } catch (IOException e) {
       e.printStackTrace();
    }
}

POST:

HttpPost httpPost = new HttpPost("http://sarjsheff.ru/");
List<NameValuePair> nvps = new ArrayList<NameValuePair>();
nvps.add(new BasicNameValuePair("username", "vip"));
nvps.add(new BasicNameValuePair("password", "secret"));
httpPost.setEntity(new UrlEncodedFormEntity(nvps));
CloseableHttpResponse response = httpclient.execute(httpPost);

Сетевые настройки:

RequestConfig config = RequestConfig.custom()
        .setSocketTimeout(5000)
        .setConnectTimeout(5000)
        .setConnectionRequestTimeout(5000)
        .build();

httpGet.setConfig(config);
CookieStore cookieStore = new BasicCookieStore();
CloseableHttpClient httpclient = HttpClients.custom().setDefaultCookieStore(cookieStore).build();

// connect

System.out.println(cookieStore.getCookies());