Java, Jersey, Salesforce and Oauth

Now that you have your Client ID, Client Secret and Password Token... 
We can start doing raw HTTP communication with salesforce. 

Use your REST Client and do:
POST to (empty content)
https://login.salesforce.com/services/oauth2/token?grant_&client_id=<client id>&client_secret=<client secret>&username=<username>&password=<password><password token>

You should get back something that looks like:
{}



Now that we know we have a valid login request, let's try to do it programmatically:

import java.io.IOException;
import java.util.HashMap;

import javax.ws.rs.client.Client;
import javax.ws.rs.client.ClientBuilder;
import javax.ws.rs.client.Entity;
import javax.ws.rs.client.WebTarget;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;

import com.fasterxml.jackson.core.JsonParseException;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.ObjectMapper;


public class OAuth {

	public static void main(String[] args) {
		Client client = ClientBuilder.newClient();
		
		
		StringBuilder content = new StringBuilder();
		content.append("https://login.salesforce.com/services/oauth2/token");
		content.append("?grant_type=password");
		content.append("&client_id=xxxxxxxx");
		content.append("&client_secret=xxxxxx");
		content.append("&username=xxxxxx");
		content.append("&password=XXXxxxxxx");
		
		WebTarget target = client.target(content.toString());

		Response r = target.request(MediaType.APPLICATION_JSON_TYPE).post(Entity.entity("", MediaType.APPLICATION_FORM_URLENCODED));

		ObjectMapper om = new ObjectMapper();
		System.out.println("AS STRING");
		String s = r.readEntity(String.class);
		System.out.println(s);
		
		try {
			System.out.println("AS HASHMAP");
			System.out.println(om.readValue(s, HashMap.class));
		} catch (JsonParseException e) {
			e.printStackTrace();
		} catch (JsonMappingException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

}
Once that works, let's improve our code a bit, to make it more generic and flexible. 
Moving OAuth token into it's own class, make the OAuth provider into a singleton (we don't want to re-create token accidentally), Move the properties into a separate location
The Properties file can later be improved, as well as the rest of the code for that matter. 


import java.io.IOException;

import javax.ws.rs.client.Client;
import javax.ws.rs.client.ClientBuilder;
import javax.ws.rs.client.Entity;
import javax.ws.rs.client.WebTarget;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;

import com.fasterxml.jackson.core.JsonParseException;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.ObjectMapper;

public class OAuth {
	private SFDCOAuthToken token;

	/**
	 * Note that we are working with a single user at this time.
	 * For multi-user application, things are going to change
	 * 
	 * @return SFDCOAuthToken
	 */
	public synchronized SFDCOAuthToken getOAuthToken() {
		if (token != null)
			return token;
		else {
			generateToken();
			return token;
		}
	}

	private synchronized void generateToken() {
		Client client = ClientBuilder.newClient();

		StringBuilder content = new StringBuilder();
		content.append("https://login.salesforce.com/services/oauth2/token");
		content.append("?grant_type=password");
		content.append("&client_id=");
		content.append(Properties.CLIENT_ID);
		content.append("&client_secret=");
		content.append(Properties.CLIENT_SECRET);
		content.append("&username=");
		content.append(Properties.USERNAME);
		content.append("&password=");
		content.append(Properties.PASSWORD);
		content.append(Properties.PASSWORD_TOKEN);

		WebTarget target = client.target(content.toString());

		Response r = target.request(MediaType.APPLICATION_JSON_TYPE).post(
				Entity.entity("", MediaType.APPLICATION_FORM_URLENCODED));

		try {
			ObjectMapper om = new ObjectMapper();
			String s = r.readEntity(String.class);
			token = om.readValue(s, SFDCOAuthToken.class);

		} catch (JsonParseException e) {
			e.printStackTrace();
		} catch (JsonMappingException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

	public static void main(String[] args) {
		OAuth oauth = new OAuth();
		System.out.println(oauth.getOAuthToken().getAccess_token());
	}
}


public class SFDCOAuthToken {
	private String id;
	private String issued_at;
	private String token_type;
	private String instance_url;
	private String signature;
	private String access_token;
	public String getId() {
		return id;
	}
	public void setId(String id) {
		this.id = id;
	}
	public String getIssued_at() {
		return issued_at;
	}
	public void setIssued_at(String issued_at) {
		this.issued_at = issued_at;
	}
	public String getToken_type() {
		return token_type;
	}
	public void setToken_type(String token_type) {
		this.token_type = token_type;
	}
	public String getInstance_url() {
		return instance_url;
	}
	public void setInstance_url(String instance_url) {
		this.instance_url = instance_url;
	}
	public String getSignature() {
		return signature;
	}
	public void setSignature(String signature) {
		this.signature = signature;
	}
	public String getAccess_token() {
		return access_token;
	}
	public void setAccess_token(String access_token) {
		this.access_token = access_token;
	}
}


public class Properties {
	final public static String LOGIN_URL = "xxx";
	final public static String CLIENT_ID = "xxx";
	final public static String CLIENT_SECRET="xxx";
	final public static String USERNAME = "xxx";
	final public static String PASSWORD = "xxx";
	final public static String PASSWORD_TOKEN = "xxx";
}