Java: Authenticate via HttpClient 4

It's often might be needed to get/post some info from the third party sites via HTTP. But, most of the times you have to be signed into that web-resources.

Authentication

Authenticate via POST with parameters:

Java

public String authenticate() throws IOException, AuthenticationException {
    HttpPost httpPost = new HttpPost(signInUrl);

    ArrayList params = new ArrayList<>(2);
    params.add(new BasicNameValuePair("username", authUser));
    params.add(new BasicNameValuePair("password", authPassword));
    httpPost.setEntity(new UrlEncodedFormEntity(params));

    logger.info("Executing Authentication Request: " + httpPost.getRequestLine());

    CloseableHttpResponse response = httpClient.execute(httpPost);

    logger.info("HTML5 Authentication Response: " + response.getStatusLine());

    int statusCode = response.getStatusLine().getStatusCode();
    if (!HttpStatus.valueOf(statusCode).is2xxSuccessful()) {
        throw new RuntimeException("Error making an Authentication request | statusCode = " + statusCode);
    }

    return EntityUtils.toString(response.getEntity());
 }

It's nice to do it in lazy way: Whenever you do any GET/POST request, check if it's failed with 401 satusCode (UNAUTHORIZED), then authenticate and re-send previously failed request.

Make requests with pre-Authorization:

Java

BasicCredentialsProvider provider = new BasicCredentialsProvider();
provider.setCredentials(new AuthScope(AuthScope.ANY_HOST, AuthScope.ANY_PORT),
                        new UsernamePasswordCredentials(authUser, authToken));
httpClient = HttpClientBuilder.create()
                              .setDefaultCredentialsProvider(provider).build();

public String makeRequest(URI uri, HttpRequestBase request) throws IOException {
    HttpHost host = new HttpHost(uri.getHost(), uri.getPort(), uri.getScheme());

    // Create AuthCache instance
    AuthCache authCache = new BasicAuthCache();
    // Generate BASIC scheme object and add it to the local auth cache
    BasicScheme basicAuth = new BasicScheme();
    authCache.put(host, basicAuth);

    // Add AuthCache to the execution context
    HttpClientContext localContext = HttpClientContext.create();
    localContext.setAuthCache(authCache);

    logger.info("Executing Request: " + request.getRequestLine());

    CloseableHttpResponse response = httpClient.execute(
                                            host,
                                            request,
                                            localContext
                                     );

    int statusCode = response.getStatusLine().getStatusCode();
    if (!HttpStatus.valueOf(statusCode).is2xxSuccessful()) {
         throw new RuntimeException("Error making Request | statusCode = " + statusCode);
    }

    return EntityUtils.toString(response.getEntity());
}

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see Also

• Post with HttpClient
• All Http Status Codes
• Spring 4 API - HttpStatus
• Java EE 7 API - Response.Status
• Apache Commons - HttpStatus
• REST (Restful Web Services)
• Themeleaf - Offsite
• Web Resource Optimizer for Java
• Wro4j - Github
• Keynote: Top JS frmeworks 2015