Consuming LinkedIn REST based Web Services using Scribe OAuth Java Library / API - http://codeoftheday.blogspot.com/2013/07/consuming-linkedin-rest-based-web.html

LinkedIn_Group_Member_Count_Servlet.java

/*
 * Consuming LinkedIn REST based Web Services using Scribe OAuth Java Library / API
 * http://codeoftheday.blogspot.com/2013/07/consuming-linkedin-rest-based-web.html
 */
package smhumayun.codeoftheday.linkedin.group;

import java.io.IOException;
import java.io.PrintWriter;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.HashMap;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.scribe.builder.ServiceBuilder;
import org.scribe.builder.api.LinkedInApi;
import org.scribe.model.OAuthRequest;
import org.scribe.model.Response;
import org.scribe.model.Token;
import org.scribe.model.Verb;
import org.scribe.oauth.OAuthService;

/**
 * Main Servlet exposed as a service which will be used by client(s) in order 
 * to determine number of group members registered in a particular LinkedIn Group
 * 
 * @author smhumayun
 */
public class MemberCountServlet extends HttpServlet {
    
    private String apiKey;
    private String apiSecret;
    private String token;
    private String tokenSecret;
    private String url;
    private String numMembersPrefix;
    private String numMembersPostfix;
    private String namePrefix;
    private String namePostfix;
    private long durationInMillis;
    private HashMap<Long, GroupInfo> groups = new HashMap<Long, GroupInfo>();
    private SimpleDateFormat df = (SimpleDateFormat) SimpleDateFormat.getDateTimeInstance();

    @Override
    public void init(ServletConfig config) throws ServletException {
        this.apiKey = config.getServletContext().getInitParameter("apiKey");
        this.apiSecret = config.getServletContext().getInitParameter("apiSecret");
        this.token = config.getServletContext().getInitParameter("token");
        this.tokenSecret = config.getServletContext().getInitParameter("tokenSecret");
        this.url = config.getServletContext().getInitParameter("url");
        try
        {
            durationInMillis = Integer.parseInt(config.getServletContext().getInitParameter("durationInMillis"));
        }
        catch(Exception e)
        {
            durationInMillis = 60 * 1000;
        }
        this.numMembersPrefix = config.getServletContext().getInitParameter("numMembersPrefix");
        this.numMembersPostfix = config.getServletContext().getInitParameter("numMembersPostfix");
        this.namePrefix = config.getServletContext().getInitParameter("namePrefix");
        this.namePostfix = config.getServletContext().getInitParameter("namePostfix");
    }

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException 
    {
        String content;
        try
        {
            long gid;
            try
            {
                gid = Long.parseLong(req.getParameter("gid"));
            }
            catch(Exception e)
            {
                gid = 0;
            }
            if(gid <= 0)
            {
                content = "INV";
                logMsg("Invalid gid : " + req.getParameter("gid"));
            }
            else
            {
                GroupInfo groupInfo = groups.get(gid);
                if(groupInfo == null)
                    groupInfo = new GroupInfo(gid);
                if(groupInfo.getLastChecked() <= 0 || System.currentTimeMillis() - groupInfo.getLastChecked() > durationInMillis )
                {
                    OAuthService oAuthService = new ServiceBuilder()
                            .provider(LinkedInApi.class)
                            .apiKey(apiKey)
                            .apiSecret(apiSecret)
                            .build();
                    OAuthRequest oAuthRequest = new OAuthRequest(Verb.GET, url.replace("{{gid}}", "" + groupInfo.getId()));
                    oAuthService.signRequest(new Token(token, tokenSecret), oAuthRequest);
                    Response response = oAuthRequest.send();
                    groupInfo.setLastChecked(System.currentTimeMillis());
                    content = response.getBody();
                    groupInfo.setName(content.substring(content.indexOf(namePrefix) + namePrefix.length() + 1, content.indexOf(namePostfix)));
                    String mc = content.substring(content.indexOf(numMembersPrefix) + numMembersPrefix.length() + 1, content.indexOf(numMembersPostfix));
                    try
                    {
                        groupInfo.setMemberCount(Long.parseLong(mc));
                        logMsg(groupInfo.getId() + " - " + groupInfo.getName() + " - " + groupInfo.getMemberCount() + " members");
                        content = "" + groupInfo.getMemberCount();
                        groups.put(groupInfo.getId(), groupInfo);
                    }
                    catch(Exception e)
                    {
                        logMsg("ERROR >>> " + groupInfo.getId() + " - " + groupInfo.getName() + " | mc {" + mc + "} | " + e.toString());
                        e.printStackTrace(System.out);
                    }
                }
                else
                {
                    content = "" + groupInfo.getMemberCount();
                    logMsg(groupInfo.getId() + " - " + groupInfo.getName() + " - " + groupInfo.getMemberCount() + " members (cached)");
                }
            }
        }
        catch(Exception e)
        {
            content = "ERR";
            e.printStackTrace(System.out);
        }
        resp.setContentType("text/plain");
        resp.setContentLength(content.length());
        PrintWriter out = resp.getWriter();
        out.print(content);
        out.close();
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        this.doGet(req, resp);
    }
    
    private void logMsg (String msg)
    {
        System.out.println(df.format(new Date(System.currentTimeMillis())) + " | " + msg);
    }
    
}