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MailChimp Integration in Java

I want to integrate MailChimp API in my java project. When I call Rest call using HttpURLConnection class, it responds with 401 code.
Here is my code:
URL url = new URL("https://us13.api.mailchimp.com/3.0/lists");
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setDoOutput(true);
conn.setRequestMethod("POST");
conn.setRequestProperty("Content-Type", "application/json");
conn.setRequestProperty("Authorization", "apikey <my-key>");
String input = "<json data>";
OutputStream os = conn.getOutputStream();
//os.write(input.getBytes());
os.flush();
if (conn.getResponseCode() != HttpURLConnection.HTTP_CREATED) {
throw new RuntimeException("Failed : HTTP error code : " + conn.getResponseCode());
}
BufferedReader br = new BufferedReader(new InputStreamReader((conn.getInputStream())));
String output;
System.out.println("Output from Server .... \n");
while ((output = br.readLine()) != null) {
System.out.println(output);
}
conn.disconnect();

I will suggest using Apache Commons Codec package for encoding.
It support various formats such as Base64 and Hexadecimal.
Earlier I was also facing the same issue. I am sharing the code that I used in my application for authenticating to Mailchimp API v-3.0
//basic imports
import org.apache.commons.codec.binary.Base64;
.
.
.
//URL to access and Mailchimp API key
String url = "https://us9.api.mailchimp.com/3.0/lists/";
//mailchimp API key
String apikey = xxxxxxxxxxxxxxxxxxxxxxxxxxx
// Authentication PART
String name = "Anything over here!";
String password = apikey; //Mailchimp API key
String authString = name + ":" + password;
byte[] authEncBytes = Base64.encodeBase64(authString.getBytes());
String authStringEnc = new String(authEncBytes);
URL urlConnector = new URL(url);
HttpURLConnection httpConnection = (HttpURLConnection) urlConnector.openConnection();
httpConnection.setRequestMethod("GET");
httpConnection.setDoOutput(true);
httpConnection.setDoInput(true);
httpConnection.setRequestProperty("Content-Type", "application/json; charset=UTF-8");
httpConnection.setRequestProperty("Accept", "application/json");
httpConnection.setRequestProperty("Authorization", "Basic " + authStringEnc);
InputStream is1 = httpConnection.getInputStream();
StringBuilder sb = new StringBuilder();
BufferedReader br = new BufferedReader(new InputStreamReader(is1, "utf-8"));
String line = null;
while ((line = br.readLine()) != null) {
sb.append(line + "\n");
}
br.close();
Now you can use StringBuilder Object sb to parse the output as required
Hope it resolves your issue :)

HTTP 401 response code means "not authorized".
You didn't set or pass your credentials properly. Is the certificate from the client set up? Here's an example of an HTTPS client.

HTTP 401 simply means you're not Authorized to send this request.
you can set username any string (the MailChimp docs suggest using anystring as a username) and your API key as a password.
In case of Postman request, you can set under the Authorization tab choose Basic Auth to set username and password. Below image shows the same.
More info about Adding/ Getting Members to/ from a Mailing List on MailChimp API 3.0, I find this article very useful.

Difference between Java Post Request and browser post request

I am trying to use api of one popular russian social networks. I am using OAuth via Java HttpUrlConnection. The problem is, when I send post data via Java, I get 401 response code. When I copy request and paste it browser, I get redirect to URL containing access token I need. That means that my post request is correct, but why when I send it with Java I get 401 error? When I send request with incorrect password, I get 200. It means that request is correct too.
private void getHomeAuth() throws Exception {
String url = "https://oauth.vk.com/authorize?client_id=APP_ID&scope=friends&redirect_uri=https://oauth.vk.com/blank.html&display=page&v=5.34&response_type=token";
URL oauth = new URL(url);
HttpURLConnection connection = (HttpURLConnection) oauth.openConnection();
connection.setRequestMethod("GET");
connection.setRequestProperty("User-Agent", USER_AGENT);
int responseCode = connection.getResponseCode();
System.out.println("Response code: " + responseCode);
BufferedReader reader = new BufferedReader(new InputStreamReader(connection.getInputStream()));
String inputLine;
StringBuilder response = new StringBuilder();
while((inputLine = reader.readLine()) != null)
response.append(inputLine + "\n");
reader.close();
PrintWriter writer = new PrintWriter("auth.html");
writer.print(response);
writer.close();
parse();
cookies = connection.getHeaderField("Set-Cookie");
referer = connection.getURL().toString();
}
private void postAuth() throws Exception {
email = URLEncoder.encode("example#gmail.com", "UTF-8");
password = "password";
_origin = URLEncoder.encode(_origin, "UTF-8");
String url = "https://login.vk.com/?act=login&soft=1";
URL post = new URL(url);
String urlParameters = "ip_h=" + ip_h + "&_origin=" + _origin + "&to=" + to + "&expire=" + expire + "&email=" + email + "&pass=" + password;
HttpsURLConnection con = (HttpsURLConnection) post.openConnection();
con.setRequestMethod("POST");
con.setRequestProperty("User-Agent", USER_AGENT);
con.setRequestProperty("Cookie", cookies);
con.setDoOutput(true);
DataOutputStream wr = new DataOutputStream(con.getOutputStream());
wr.writeBytes(urlParameters);
wr.flush();
wr.close();
int responseCode = con.getResponseCode();
System.out.println("Sent post. Response code: " + responseCode + "\nRequest: " + post.toString() + urlParameters + "\nRequestMethod: " + con.getRequestMethod());
}
I also tryied to send this request via addon in browser, and the result was correct. I obtained access token from redirect link.
Maybe the problem is that something inside request is incorrect. I have tried to monitor requests from java app, but I failed.

My experience with this kind of problem is that the http request that first authenticates the user also puts cookies (scope varies from case to case) into the response and subsequent http requests are expected to contain those cookies. Look very closely at the complete returned response headers to see what cookies might have been returned.

Java : How to avoid hand-shake mode with HttpURLConnection authentication?

I am calling a REST Web Service with HttpURLConnection like so (this is not the actual URL and credentials, of course I changed the values before posting on a public forum)...
String uri = "http://99.82.36.238:8443/media/crowd?";
String query = String.format("office_code=%s&content_type_code=%s",
URLEncoder.encode("USA"), URLEncoder.encode("SGV"));
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod("GET");
conn.setRequestProperty("Accept", "text/xml");
String username = "userNewbie";
String password = "password";
conn.setRequestProperty("Authorization", CredentialsEncoder.userNamePasswordBase64(username,password));
if (conn.getResponseCode() != 200) {
throw new RuntimeException("Failed : HTTP error code : "
+ conn.getResponseCode() + " because " + conn.getResponseMessage());
}
BufferedReader br = new BufferedReader(new InputStreamReader(
(conn.getInputStream())));
The problem is that the service that I am calling does not work in a hand-shake mode. Meaning it needs me to send the creds the first time the request is made, rather than making the request and getting the 403 and then sending the cred.
Can anyone suggest how to modify the above code to meet that requirement?
Thanks.

How to get redirected URL and content using HttpURLConnection

Sometimes my URL will redirect to a new page, so I want to get the URL of the new page.
Here is my code:
URL url = new URL("http://stackoverflow.com/questions/88326/");
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setInstanceFollowRedirects(true);
System.out.println(conn.getURL().toString());
The output is:
stackoverflow.com/questions/88326/does-elmah-handle-caught-exceptions-as-well
It works well for the Stack Overflow website, but for the sears.com site, it doesn't work.
If we enter the URL blow:
http://www.sears.com/search=iphone
the output is still:
http://www.sears.com/search=iphone
But actually, the page will redirect to:
http://www.sears.com/tvs-electronics-phones-all-cell-phones/s-1231477012?keyword=iphone&autoRedirect=true&viewItems=25&redirectType=CAT_REC_PRED
How can I solve this problem?

Simply call getUrl() on URLConnection instance after calling getInputStream():
URLConnection con = new URL(url).openConnection();
System.out.println("Orignal URL: " + con.getURL());
con.connect();
System.out.println("Connected URL: " + con.getURL());
InputStream is = con.getInputStream();
System.out.println("Redirected URL: " + con.getURL());
is.close();
If you need to know whether the redirection happened before actually getting it's contents, here is the sample code:
HttpURLConnection con = (HttpURLConnection) (new URL(url).openConnection());
con.setInstanceFollowRedirects(false);
con.connect();
int responseCode = con.getResponseCode();
System.out.println(responseCode);
String location = con.getHeaderField("Location");
System.out.println(location);

actually we can use HttpClient, which we can set HttpClient.followRedirect(true)
HttpClinent will handle the redirect things.

Java HttpURLConnection no cookies

English:
Hello, I'm currently trying to do a login with HttpURLConnection and then get the session cookies...
I already tried that on some test pages on my own server, and that works perfectly. When i send "a=3&b=5" i get "8" as cookie (PHP page adds both together)!
But when i try that at the other page, the output is just the page as if I just sent nothing with POST :(
General suggestions for improvement are welcome! :)
My Code:
HttpURLConnection conn = (HttpURLConnection) new URL(url).openConnection();
conn.setDoInput(true);
conn.setDoOutput(true);
conn.setRequestMethod("POST");
conn.setRequestProperty("useragent", "Mozilla/5.0 (Windows NT 6.1; WOW64; rv:17.0) Gecko/20100101 Firefox/17.0");
conn.setRequestProperty("Connection", "keep-alive");
DataOutputStream out = new DataOutputStream(conn.getOutputStream());
out.writeBytes("USER=tennox&PASS=*****");
out.close();
BufferedReader in = new BufferedReader(new InputStreamReader(conn.getInputStream()));
String line;
String response = new String();
while ((line = in.readLine()) != null) {
response = response + line + "\n";
}
in.close();
System.out.println("headers:");
int i = 0;
String header;
while ((header = conn.getHeaderField(i)) != null) {
String key = conn.getHeaderFieldKey(i);
System.out.println(((key == null) ? "" : key + ": ") + header);
i++;
}
String cookies = conn.getHeaderField("Set-Cookie");
System.out.println("\nCookies: \"" + cookies + "\"");

I see the following possibilities why you don't get a cookie.
server does NOT send cookies at all
server does not use the values PASS and USER
server want to have a session before login.
POST protocol is wrong or incomplete
server expects parameters by GET