Simple Java Program using LinkedIn API

The below program will helps you to fetch & view linkedIn data in a short time.

Follow this link to download the jars & to get token, secret to work with LinkedIn API

Simple Java Program. To get the LinkedIn details about the current user [Who created the token & secret key]

public static void main(String[] args) {

String linkedinKey = "C2E7PG..";    //Your LinkedIn key
String linkedinSecret = "9hyC6.. ";//Your LinkedIn Secret
OAuthConsumer consumer = new DefaultOAuthConsumer(      linkedinKey,linkedinSecret);
  
OAuthProvider provider = new DefaultOAuthProvider("https://api.linkedin.com/uas/oauth/requestToken",
                 "https://api.linkedin.com/uas/oauth/accessToken",
                 "https://api.linkedin.com/uas/oauth/authorize");
  
System.out.println("Fetching request token from LinkedIn...");  
String authUrl;
try {
authUrl = provider.retrieveRequestToken(consumer, OAuth.OUT_OF_BAND);
System.out.println("Check the below link and grant this app authorization -You will get Pin Number.Copy it\n" + authUrl                  );
System.out.println("Enter the PIN code and hit ENTER when you're done:");
} catch (OAuthMessageSignerException e1) {
 e1.printStackTrace();
} catch (OAuthNotAuthorizedException e1) {
 e1.printStackTrace();
} catch (OAuthExpectationFailedException e1) {
 e1.printStackTrace();
} catch (OAuthCommunicationException e1) {
 e1.printStackTrace();
}
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
String pin;
try {
pin = br.readLine();   
System.out.println("Fetching access token from LinkedIn...");
provider.retrieveAccessToken(consumer, pin);
System.out.println("Access token: " + consumer.getToken());
System.out.println("Token secret: " + consumer.getTokenSecret());
URL url = new URL("http://api.linkedin.com/v1/people/~:(id,first-name,last-name,picture-url,headline)");
           
HttpURLConnection request = (HttpURLConnection) url.openConnection();
           consumer.sign(request);
           request.connect();
System.out.println("Sending request to LinkedIn...");
String responseBody = convertStreamToString(request.getInputStream());
System.out.println("Response: " + request.getResponseCode() + " "
                   + request.getResponseMessage() + "\n" + responseBody);

} catch (OAuthMessageSignerException e) {   
  e.printStackTrace();
} catch (OAuthNotAuthorizedException e) {  
  e.printStackTrace();
} catch (OAuthExpectationFailedException e) {
e.printStackTrace();
} catch (OAuthCommunicationException e) {   
  e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
 public static String convertStreamToString(InputStream is) {
 
 BufferedReader reader = new BufferedReader(new InputStreamReader(is));
 StringBuilder sb = new StringBuilder();
 String line = null;
  try {
while ((line = reader.readLine()) != null) {
                 sb.append(line + "\n");
       }
  } catch (IOException e) {
             e.printStackTrace();
  } finally {
  try {
     is.close();
 } catch (IOException e) {
     e.printStackTrace();
 }
}
      return sb.toString();
}
}

    

Output

Fetching request token from LinkedIn...
Check the below link and grant this app authorization -You will get Pin Number.Copy it
https://api.linkedin.com/uas/oauth/authorize?oauth_token=dcb835667-a5d7-4e95-91f9-fde4b9b47e3a
Enter the PIN code and hit ENTER when you're done:
59278
Fetching access token from LinkedIn...
Access token: f0f94b3d-50b9-4549-bd96-5d1ea3ba7a9c
Token secret: f2b13c99-f206-4612-bf9e-2afc1387bc1a
Sending request to LinkedIn...
Response: 200 OK

  GtYKzPiNkX
  Sundari Shree
  Gunasekaran
  Software Engineer at Vision Tech Solutions

Note: By passing the different URL’s as parameter You can check all the available information in LinkedIn .

URL url = new URL("http://api.linkedin.com/v1/people/~:(id,first-name,last-name,picture-url,headline)");

This URL is to get about the people information.

LinkedIn API

I have just started to work in this API with Java .bcoz am basically a Java developer.

Step-up LinkedIn API

To start your work with LinkedIn API, You need to get the
Consumer key \ API key & Consumer Secret \Secret Key.
Go for this link to get your Consumer key & Consumer Secret for your application
https://www.linkedin.com/secure/developer
You have to give application name & some regular fields you have to fill up.

IDE & JDK Version
Working with IBM Rational Application Developer-Version: 7.0.0
jdk used is 1.6 version.
You can work on Eclipse also.

Download 3 Jars

1.commons-codec-1.3.jar –
http://code.google.com/p/linkedin-j/source/browse/#svn/trunk/linkedin-j/lib

2.linkedin-j.jar - http://code.google.com/p/linkedin-j/source/browse/#svn/trunk/linkedin-j/dist [version downloaded is May24]

3.signpost-core-1.2.1.1.jar - http://code.google.com/p/linkedin-j/source/browse/#svn/trunk/linkedin-j/lib

Included the jar in the class path and try to access the class in the jar

Got :( Error bcoz I tried out downloading snapshot version of linkedIn.jar ,
Not able to get the authService object.

final LinkedInOAuthService oauthService = LinkedInOAuthServiceFactory.getInstance().createLinkedInOAuthService(consumerKeyValue, consumerSecretValue); 

Error got
Exception in thread "main" java.lang.NoClassDefFoundError: oauth/signpost/signature/OAuthMessageSigner
With the support of Linked Forum got rid from this issue.
http://developer.linkedin.com/message/5585#5585

Lets start coding ....
How to get LinkedIn –token, token secret & Authorization URL using consumer key & consumer secret?

final LinkedInOAuthService oauthService = LinkedInOAuthServiceFactory.getInstance().createLinkedInOAuthService(consumerKeyValue, consumerSecretValue); 
LinkedInRequestToken requestToken = oauthService.getOAuthRequestToken("your application url");
String token = requestToken.getToken();
String tokenSecret = requestToken.getTokenSecret();
String authUrl = requestToken.getAuthorizationUrl(); 

Set all this objects in session.Inorder to proceed with the functions.

session.setAttribute("LINKEDIN_TOKEN", token);
session.setAttribute("LINKEDIN_TOKEN_SECRET", tokenSecret);
session.setAttribute("LINKEDIN_REQUEST_TOKEN", requestToken );
session.setAttribute("LINKEDIN_AUTH_URL", authUrl );

After execution of these codes, the service will be verfied .

Place this authorized url as a link in a jsp page.
When the link is clicked it asks for your LinkedIn username & Password.

How to get the LinkedIn –Access Token?

Once your application ,username& password are verified you will get a auth_verifier with the url.

String oauthVerifier = request.getParameter("oauth_verifier");
//Pass the requestToken[session.getAttribute("LINKEDIN_REQUEST_TOKEN")] & oauthVerifier to get accesstoken
LinkedInAccessToken accessToken = oauthService.getOAuthAccessToken(requestToken, oauthVerifier);

Set the access token in a session

session.setAttribute("LINKEDIN_ACCESS_TOKEN", accessToken);

How to create the Client Object?

Create the factory object by passing consumerKeyValue & consumerSecretValue

final LinkedInApiClientFactory factory = LinkedInApiClientFactory.newInstance(consumerKeyValue, consumerSecretValue); 

Pass the access token to get the client object .

final LinkedInApiClient client = factory.createLinkedInApiClient(accessToken);

Functions in Linked-Id

Check out all the functions available in the LinedIn API

I have given some of the main functions with example code ,Here it goes...

To get the Current user Profile

Person profile = client.getProfileForCurrentUser(EnumSet.of(ProfileField.ID));
System.out.print("CurrentUsers Profile-Id >>"+profile.getId());

To get specific information of the Current User

Set the fields which you need .

Person userprofile = client.getProfileById(profile.getId(), EnumSet.of(ProfileField.FIRST_NAME,ProfileField.LAST_NAME,ProfileField.HEADLINE,ProfileField.INDUSTRY,ProfileField.API_STANDARD_PROFILE_REQUEST, ProfileField.PICTURE_URL, ProfileField.PUBLIC_PROFILE_URL));
System.out.println("PersonID:" + userprofile.getId()); 
System.out.println("Name:"+ userprofile.getFirstName()+ " " + userprofile.getLastName()); 
System.out.println("Headline:" + userprofile.getHeadline()); 
System.out.println("API Request:" + userprofile.getApiStandardProfileRequest()); 
System.out.println("Industry:" + userprofile.getIndustry()); 
System.out.println("Picture:" + userprofile.getPictureUrl());
System.out.println("Public URL:" + userprofile.getPublicProfileUrl());

To get the connections of the Current User
Set the fields which you need .

final Set connectionFields = EnumSet.of(ProfileField.ID, ProfileField.FIRST_NAME, ProfileField.LAST_NAME, ProfileField.HEADLINE, ProfileField.INDUSTRY, ProfileField.CURRENT_STATUS, ProfileField.CURRENT_STATUS_TIMESTAMP,ProfileField.API_STANDARD_PROFILE_REQUEST, ProfileField.EDUCATIONS,ProfileField.PUBLIC_PROFILE_URL, ProfileField.POSITIONS, ProfileField.LOCATION, ProfileField.PICTURE_URL);

Pass the connection fields & get the connection object

Connections tryconnections = client.getConnectionsForCurrentUser(connectionFields);

Iterate the Person object from the person list.

for (Person person : connections.getPersonList()) { 
System.out.println( "PersonId :"+ person.getId());
System.out.println("Name:" + person.getFirstName() + " " + person.getLastName()); 
System.out.println("Headline:" + person.getHeadline()); 
System.out.println("Industry:" + person.getIndustry()); 
System.out.println("Picture:" + person.getPictureUrl()); 

//To get the Location details

Location location = person.getLocation(); 
System.out.println("Location:" +location.getName()+" - "+location.getCountry().getCode());
System.out.println("API Request:" + person.getApiStandardProfileRequest()); 
System.out.println("Public URL:" + person.getPublicProfileUrl()); 

//To get the Header information

ApiStandardProfileRequest apiStandardProfileRequest=person.getApiStandardProfileRequest();
System.out.println("Header:" + apiStandardProfileRequest.getHeaders());
}

To get Profile ID by using public url

Pass the public URL of a person & connection fields

Person checkPerson = client.getProfileByUrl("public url of a person,connectionFields);
System.out.println("PersonID:" + checkPerson.getId()); 
System.out.println("Name:" + checkPerson.getFirstName() + " " + checkPerson.getLastName()); 
.
.

You can get all the data of a person for whatever fields mentioned in the connection field.

To get Profile ID by using Person ID

Pass the PersonID & required fields 
Person othersProfile = client.getProfileById(userID, EnumSet.of(ProfileField.FIRST_NAME,ProfileField.LAST_NAME,ProfileField.HEADLINE,ProfileField.INDUSTRY,ProfileField.API_STANDARD_PROFILE_REQUEST, ProfileField.PICTURE_URL, ProfileField.PUBLIC_PROFILE_URL));

To invite by using E-mail
Pass the client object,emailId of the person you want to invite,firsname,lastname,subject & message.

inviteByEmailID(client,emailID, firstName, lastName,subject,msg);

Note:e-mail,first name & last name should not be passed Empty.Null Pointer Exception will be thrown.

To invite by using PersonId

Pass the header token value ,userId,subject & message.

Code to take the header token value

String tokenValue=authHeader.getHttpHeaderList().get(0).getValue(); 
System.out.println("tokenValue "+tokenValue);
client.sendInviteById("PersonID", subject, msg,tokenValue);

To send message to specific group of people

You have to pass the id’s of the people in a list whom you want to send message

Iterate the list in a for loop

client.sendMessage(Arrays.asList(((String) list.get(i)).split(",")), subj, message);

To Search within Linked In

We can search by passing company name,keyword,title,CountryCode
…etc

Example code is given for searching connection based on particular company
Function to put the search parameters [Company name is set]

private static Map getSearchParameters() {
Map searchParameters = new EnumMap(SearchParameter.class);  
searchParameters.put(SearchParameter.COMPANY, "Kyyba"); 
return searchParameters;
}
Map SearchParameter, String searchParameters = getSearchParameters();

Pass the search Parameters to find the people based on search

People people = client.searchPeople(searchParameters);

To get the people information

for (Person person : people.getPersonList()) {
System.out.println(person.getId() + ":" + person.getFirstName() + " " + person.getLastName() + ":" + person.getHeadline());
}

We can't get the connections of connections

Connections otherscon = client.getConnectionsById("ProfielID");

Error will be thrown as Access to other member's connections denied.

In Linkedin forum they have mentioned as currently they not support getting other people's connections.

http://developer.linkedin.com/thread/1329
http://developer.linkedin.com/message/3706;jsessionid=3E26C276AF047188942CDE50F562B638.node0