CODEWITHSUNDEEP
javaoauth-2.0google-contacts-api
Cotheer
Cotheer

Reputation: 191

Google Contacts v3 API & OAuth v2, in Java

For the last few days i've been trying to get a list of google contacts using the above APIs. Needles to say, unsuccessfully. Google documentation (which is a total mess if i may say) has not been very helpful regarding my problem. The thing is, i have no idea how to authorize the ContactsService object using OAuth v2 API. I've already downloaded Google OAuth2.0 library which, again, has no proper documentation and/or no proper examples for total beginners like myself.

So to sum it up, does anyone have any working "Hello world" type of examples or any kind of "guidance" for the above problem?

As a side note, i did managed to get the contacts using the Scribe API, but as you may know, the response is in the xml/json format which needs to be parsed first and that's not what i want.

Thank you

Upvotes: 9

Views: 7838

Answers (2)

Cotheer
Cotheer

Reputation: 191

It seems i have finally made some progress. The problem, apparently, was that there are bunch of different OAuth2 libraries out there, some of them are either deprecated or just won't work with Contacts v3, that is, generated access token will be invalid (that's what i concluded).

So for authorization and generating access token i've used Google API Client 1.14.1 (beta), and my code is as follows:

Servlet 1 (generating auth URL):

protected void processRequest(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {

        response.setContentType("text/html;charset=UTF-8");           

        GoogleAuthorizationCodeRequestUrl authorizationCodeURL=new GoogleAuthorizationCodeRequestUrl(CLIENT_ID, REDIRECT_URL, SCOPES);

        authorizationCodeURL.setAccessType("offline");//For future compatibility

        String authorizationURL=authorizationCodeURL.build();
        System.out.println("AUTHORIZATION URL: "+authorizationURL); 

        response.sendRedirect(new URL(authorizationURL).toString());

}

Servlet 2 (dealing with access token)

protected void processRequest(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    response.setContentType("text/html;charset=UTF-8");
    PrintWriter out = response.getWriter();


    out.println("<html>");
    out.println("<head>");
    out.println("<title>Servlet SignInFinished</title>");
    out.println("</head>");
    out.println("<body>");


    HttpTransport transport = new NetHttpTransport();
    JsonFactory jsonFactory = new JacksonFactory();
    GoogleAuthorizationCodeTokenRequest authorizationTokenRequest = new GoogleAuthorizationCodeTokenRequest(transport, jsonFactory, CLIENT_ID, CLIENT_SECRET, request.getParameter("code"), REDIRECT_URL);

    GoogleTokenResponse tokenResponse = authorizationTokenRequest.execute();

    out.println("OAuth2 Access Token: " + tokenResponse.getAccessToken());

    GoogleCredential gc = new GoogleCredential();
    gc.setAccessToken(tokenResponse.getAccessToken());

    ContactsService contactsService = new ContactsService("Lasso Project");
    contactsService.setOAuth2Credentials(gc);

    try {
        URL feedUrl = new URL("https://www.google.com/m8/feeds/contacts/default/full");

        Query myQuery = new Query(feedUrl);
        myQuery.setMaxResults(1000);

        ContactFeed resultFeed = contactsService.query(myQuery, ContactFeed.class);

        for (int i = 0; i < resultFeed.getEntries().size(); i++) {
            out.println(resultFeed.getEntries().get(i).getTitle().getPlainText() + "<br/>");
        }

    } catch (Exception e) {
        System.out.println(e);
    }

    out.println("</body>");
    out.println("</html>");
}

NOTE: If you are using Client ID for Web Applications, REDIRECT_URL must be one of Redirect URLs you entered when registering application via Google console.

Well, I hope this'll be helpful to some of you :).

Upvotes: 9

itsu
itsu

Reputation: 222

I had trouble as well trying to retrieve google contacts. With OAuth2.0, you first need to get an access token. Then it gets easy, you can request for the id of the group you are looking for : 

import com.google.gdata.client.contacts.ContactsService;
import com.google.gdata.data.contacts.ContactEntry;
import com.google.gdata.data.contacts.ContactFeed;
import com.google.gdata.data.contacts.ContactGroupEntry;
import com.google.gdata.data.contacts.ContactGroupFeed;

private static final String GROUPS_URL = "https://www.google.com/m8/feeds/groups/default/full";

private int getIdOfMyGroup() {
    ContactsService contactsService = new ContactsService("MY_PRODUCT_NAME");
    contactsService.setHeader("Authorization", "Bearer " + MY_ACCESS_TOKEN);

    try {
        URL feedUrl = new URL(GROUPS_URL);
        ContactGroupFeed resultFeed = contactsService.getFeed(feedUrl, ContactGroupFeed.class);
        // "My Contacts" group id will always be the first one in the answer
        ContactGroupEntry entry = resultFeed.getEntries().get(0);

        return entry.getId();
    } catch (...) { ... }
}

Eventually you will be able with the group id to request its contacts :

private static final String CONTACTS_URL = "https://www.google.com/m8/feeds/contacts/default/full";
private static final int MAX_NB_CONTACTS = 1000;

private List<ContactEntry> getContacts() {
    ContactsService contactsService = new ContactsService("MY_PRODUCT_NAME");
    contactsService.setHeader("Authorization", "Bearer " + MY_ACCESS_TOKEN);

    try {
        URL feedUrl = new URL(CONTACTS_URL);
        Query myQuery = new Query(feedUrl);
                    // to retrieve contacts of the group I found just above
        myQuery.setStringCustomParameter("group", group);
        myQuery.setMaxResults(MAX_NB_CONTACTS);
        ContactFeed resultFeed = contactsService.query(myQuery, ContactFeed.class);
        List<ContactEntry> contactEntries = resultFeed.getEntries();

        return contactEntries;
    } catch (...) { ... }
}

Upvotes: 0

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