Open Connection SalesForce Rest API

Hi

I have written a sample code in java to make a persistent connection to Salesforce's Rest API, This example uses Oauth Grant_Type ="password" to provide a fresh access_token each time the request is made.

Please find the code below. To make this code work you need to add package <httpcomponents-client> to your classpath. which can easily be downloaded from  http://hc.apache.org/httpcomponents-client-ga/

 


Please find the code :

package connection;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;

import org.apache.http.HttpException;
import org.apache.http.HttpResponse;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.client.utils.URLEncodedUtils;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.params.HttpConnectionParams;
import org.apache.http.params.HttpParams;
import org.apache.http.protocol.HTTP;
import org.apache.http.util.EntityUtils;
import org.json.simple.JSONValue;



public class OauthConnection {

    //Variables to be populated after gaining the Access token.
    private String accessToken = null;
    private Map<String, String> oauthLoginResponse;
   
    //Constants to be used in this class.
    private static final String clientId = <Your Client ID>;  
    private static final String clientSecret = <Your Client Secret>;
    private static final String environment = "<SalesForce Instance>";
    private static final String authUrl = "/services/oauth2/token";
    private static final String restUrl = "/services/data/v25.0/";
    private static final String queryUrl = "/services/data/v25.0/query";
    private static final String username = "<Your SFDC USER NAME>";
    private static final String password = <SFDC PASSWORD WITH SECURITY TOKEN>;
   
   
   
    public static void main(String[] args){
        try{
       
            OauthConnection oc = new OauthConnection();
            oc.oAuthSessionProvider();
           
            oc.executeQuery();
       
        }catch(Exception e){
            e.printStackTrace();
        }
      }
       
    public void oAuthSessionProvider()
            throws HttpException, IOException
    {
        // Set up an HTTP client that makes a connection to REST API.
        DefaultHttpClient client = new DefaultHttpClient();
        HttpParams params = client.getParams();
        params.setParameter(HttpConnectionParams.CONNECTION_TIMEOUT, 30000);

        // Set the SID.
        System.out.println("Logging in as " + username + " in environment " + environment);
        String baseUrl = environment + authUrl;
       
        // Send a post request to the OAuth URL.
        HttpPost oauthPost = new HttpPost(baseUrl);
       
        // The request body must contain these 5 values.
        List<BasicNameValuePair> parametersBody = new ArrayList<BasicNameValuePair>();
        parametersBody.add(new BasicNameValuePair("grant_type", "password"));
        parametersBody.add(new BasicNameValuePair("username", username));
        parametersBody.add(new BasicNameValuePair("password", password));
        parametersBody.add(new BasicNameValuePair("client_id", clientId));
        parametersBody.add(new BasicNameValuePair("client_secret", clientSecret));
        oauthPost.setEntity(new UrlEncodedFormEntity(parametersBody, HTTP.UTF_8));

        // Execute the request.
        System.out.println("POST " + baseUrl + "...\n");
      
        HttpResponse response = client.execute(oauthPost);
        int code = response.getStatusLine().getStatusCode();
      
        System.out.println("Code >> " +code);
       
        //populate Response map to fetch ACCESS TOKEN for any future call.
        this.oauthLoginResponse = (Map<String, String>)JSONValue.parse(EntityUtils.toString(response.getEntity()));
       
        System.out.println("OAuth login response");
       
        for (Map.Entry<String, String> entry : oauthLoginResponse.entrySet())
        {
            System.out.println(String.format("  %s = %s", entry.getKey(), entry.getValue()));
        }
       
        //Populate Access Token 
        this.accessToken = oauthLoginResponse.get("access_token");
        System.out.println("");
    }
   
    public void executeQuery(){
         DefaultHttpClient httpClient = new DefaultHttpClient();
       
        List<BasicNameValuePair> qsList = new ArrayList<BasicNameValuePair>();
        qsList.add(new BasicNameValuePair("q", "Select a.ParentId, a.OwnerId, a.Name, a.IsPrivate,  a.Id, a.Description, a.ContentType, a.BodyLength, a.Body " +
                "                                From Attachment a where  a.ParentId = '00390000006DEGb'"));
       
        String queryString = URLEncodedUtils.format(qsList, HTTP.UTF_8);
        HttpGet get = new HttpGet(environment + queryUrl+"?"+queryString);
        get.setHeader("Authorization", "OAuth " + accessToken);
        try{
            HttpResponse queryResponse = httpClient.execute(get);
           
            System.out.println(queryResponse.getStatusLine().getReasonPhrase());
              Map<String, Object> querynfo = (Map<String, Object>)
                        JSONValue.parse(EntityUtils.toString(queryResponse.getEntity()));
             
              System.out.println("Query response");
                for (Map.Entry<String, Object> entry : querynfo.entrySet())
                {
                    System.out.println(String.format("  %s = %s", entry.getKey(), entry.getValue()));
                }
                System.out.println("");
             
        }catch(Exception e){
            e.printStackTrace();
        }
       
    }
 }