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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.

Android DDNS update URL

I try to update my DDNS (No-IP) in a android client.
I make a request to the following URL.(Discription)
http://username:password#dynupdate.no-ip.com/nic/update?hostname=mytest.testdomain.com&myip=1.2.3.4
When i am using my webbrowser, everything works fine.
"good [ip-address]"
But my android client only gets the response "nochange"
URL url = new URL("http://" + USERNAME + ":" + PASSWORD + "#dynupdate.no-ip.com/nic/update?hostname=" + HOSTNAME + "&myip=" + IP_ADDRESS);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod("GET");
int i = conn.getResponseCode();
stringBuilder = new StringBuilder();
bufferedReader = new BufferedReader(new InputStreamReader(conn.getInputStream(), "UTF-8"));String line;
while ((line = bufferedReader.readLine()) != null) {
stringBuilder.append(line + "\n");
}

From http://www.noip.com/integrate/request:
When making an update it is important that your http request include an HTTP User-Agent to help No-IP identify different clients that access the system. Clients that do not supply a User-Agent risk being blocked from the system.
So you'll probably need to set the UserAgent as described on that page, specifically, something like this (replace these details with the datails of your own app):
User-Agent: NameOfUpdateProgram/VersionNumber maintainercontact#domain.com
See here for details of how to set the UserAgent when using HttpUrlConnection, something like this should work:
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod("GET");
hc.setRequestProperty("User-Agent", "NameOfUpdateProgram/VersionNumber maintainercontact#domain.com");

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.

Send http post request to URL with query string using HttpPost client in java

I need to send a post request to url which is formed as follows:
www.abc.com/service/postsomething?data={'name':'rikesh'}&id=45
Using HttpPost client in java, how can post request to such query strings
I could connect from javascript easily through ajax but from java client, it's failing.
(I know sending querystring in post request is stupid idea. Since I am connecting to someone else's server I cannot not change the way it is)

Here is one way to send JSON in a POST request using Java (without Apache libraries). You might find this helpful:
//init
String json = "{\"name\":\"rikesh\"}";
String requestString = "http://www.example.com/service/postsomething?id=45";
//send request
URL url = new URL(requestString);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setDoOutput(true);
conn.setRequestMethod("POST");
conn.setRequestProperty("Content-Type", "application/json");
OutputStream os = conn.getOutputStream();
os.write(json.getBytes());
os.flush();
int responseCode = conn.getResponseCode();
//get result if there is one
if(responseCode == 200) //HTTP 200: Response OK
{
String result = "";
BufferedReader br = new BufferedReader(new InputStreamReader(conn.getInputStream()));
String output;
while((output = br.readLine()) != null)
{
result += output;
}
System.out.println("Response message: " + result);
}

set methods aren't working for HttpsURLConnection

I'm trying to make a rest request in java. I tested the web service using RestClient in Firefox and it works great.
When i try to modify the HttpsUrlConnection instance in java the values aren't changing and i get a 500 response code.
Here's my code:
public String getAuthToken() throws IOException {
URL url =new URL("https://webserviceurl"); // webservice url is the url of the webservice
String data = URLEncoder.encode("username") + "=" + URLEncoder.encode("myusername","UTF-8");
data+= "&" + URLEncoder.encode("password") + "=" + URLEncoder.encode("pass","UTF-8");
HttpsURLConnection conn =(HttpsURLConnection) url.openConnection();
conn.setUseCaches(false);
conn.setHostnameVerifier(new AllowAllHostnameVerifier()); //this works HostName verifier changes
conn.setRequestMethod("POST"); // this doens't work. requestMethod is still set to GET
conn.setDoOutput(true); // this doesnt work. DoOutput still set on false
conn.setRequestProperty("Content-Type", "application/json"); // doens't work either
OutputStreamWriter wr = new OutputStreamWriter(conn.getOutputStream(),"UTF-8");
wr.write(data);
wr.flush();
wr.close();
//conn has a 500 response code
if (conn.getResponseCode()==200)
{
InputStream is = conn.getInputStream();
InputStreamReader isr = new InputStreamReader(is);
BufferedReader rd = new BufferedReader(isr);
String token = rd.readLine();
rd.close();
return token;
}
else
return null;
}
I'm stucked at this point and cannot find anything to make this work.
Thank you!

I actually think it's a bug with HttpsURLConnection. As i changed it to a HttpURLConnection object everything works just fine.