Salesforce REST API implementation - JAVA

This post demonstrates the following basic use cases for the REST API:
- authentication with OAuth 2.0 (This is for development purposes only. Not a real implementation.)
- querying (using account records)
- inserting (using a contact record related to one of the retrieved account records)
- updating (updates contact record added in previous step)

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.IOException;
import java.io.UnsupportedEncodingException;

import org.apache.http.Header;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicHeader;
import org.apache.http.util.EntityUtils;

import org.json.JSONException;
import org.json.JSONObject;

/**
 * This program demonstrates the following basic use cases for the REST API:
 * - authentication with OAuth 2.0 (This is for development purposes only. Not a real implementation.)
 * - querying (using account records)
 * - inserting (using a contact record related to one of the retrieved account records)
 * - updating (updates contact record added in previous step)
 * 
 */
public class REST_Code extends Object {
    //---------Credentials----------
    //Credentials providing access to a specific Salesforce organization.
    private static final String userName = "demo@demo.com"; // COPY USERNAME
    private static final String password = "passwordTOKEN"; // COPY PASSWORD AND TOKEN
    
    //---------REST and OAuth-------
    //Portions of the URI for REST access that are re-used throughout the code
    private static String OAUTH_ENDPOINT = "/services/oauth2/token";
    private static String REST_ENDPOINT = "/services/data";
    
    //Holds URI returned from OAuth call, which is then used throughout the code.
    String baseUri;
    
    //The oauthHeader set in the oauth2Login method, and then added to
    //each HTTP object that is used to invoke the REST API.
    Header oauthHeader;
    
    //Basic header information added to each HTTP object that is used
    //to invoke the REST API.
    Header prettyPrintHeader = new BasicHeader("X-PrettyPrint", "1");

    //----------Data specific---------
    //Retrieved accountId that is used when contact is added.
    private static String accountId;
    
    //Id of inserted contact. Used to update contact.
    private static String contactId;

    //----------Utility-------------
    //Used to get input from console.
    private static BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));

    //================Code starts here===================
    public static void main(String[] args) {
        new REST_Code();
    }
    
    /**
     * This class holds all the values related to the credentials needed to
     * make the OAuth2 request for authentication. Normally they would not be set in
     * this manner.
     */ 
    class UserCredentials {
        String loginInstanceDomain = "cs10.salesforce.com"; // COPY YOUR SERVER INSTANCE
        String apiVersion = "37"; // COPY YOU API VERSION
        String userName = REST_Code.userName;
        String password = REST_Code.password;
        String consumerKey = "CONSUMER_KEY"; // COPY YOUR CONSUMER KEY      
        String consumerSecret = "CONSUMER_SECRET"; // COPY YOUR CONSUMER SECRET
        String grantType = "password";
    }

    /**
     * Constructor drives console interaction and calls appropriate methods.
     */
    public REST_Code() {

        showMenu();
        boolean invalidValue = true;
        int executionOption = 99;
        String choice = getUserInput("Enter option: ");
        while (invalidValue) {
            try {
                executionOption = Integer.parseInt(choice);
                if ((executionOption < 1 || executionOption > 4) && executionOption!=99) {
                    System.out.println("Please enter 1, 2, 3, 4, or 99.\n");
                    choice = getUserInput("Enter the number of the sample to run: ");
                    showMenu();
                } else {
                    invalidValue = false;
                }
            } catch (Exception e) {
                System.out.println("Invalid value. Please enter 1, 2, 3, 4, or 99.\n");
                choice = getUserInput("Enter the number of the sample to run: ");
                showMenu();
            }           
        }
        if (executionOption == 99) {
            System.out.println("No action taken");
        } else {
            //Login is done for option 1, as well as all other valid options.
            this.oauth2Login();
            if (executionOption >= 2) {
                this.restGetExample();
            }
            if (executionOption >= 3) {
                if (accountId != null) {
                    this.restPostExample(accountId);                
                } else {
                    System.out.println("Account not found.");
                }
            }
            if (executionOption == 4) {
                if (contactId != null) {
                    this.restPatchExample(contactId);
                }  else {
                    System.out.println("Contact not found.");
                }
            }   
        }   
        System.out.println("Program complete.");
    }

    /**
     * This method connects the program to the Salesforce organization using OAuth. 
     * It stores returned values for further access to organization.
     * @param userCredentials Contains all credentials necessary for login
     * @return
     */
    public HttpResponse oauth2Login() {
        System.out.println("_______________ Login _______________");
        OAuth2Response oauth2Response = null;
        HttpResponse response = null;
        UserCredentials userCredentials = new UserCredentials();
        String loginHostUri = "https://" + userCredentials.loginInstanceDomain + OAUTH_ENDPOINT;
        
        try {
            //Construct the objects for making the request
            HttpClient httpClient = new DefaultHttpClient();
            HttpPost httpPost = new HttpPost(loginHostUri);
            StringBuffer requestBodyText = new StringBuffer("grant_type=password");
            requestBodyText.append("&username=");
            requestBodyText.append(userCredentials.userName);
            requestBodyText.append("&password=");
            requestBodyText.append(userCredentials.password);
            requestBodyText.append("&client_id=");
            requestBodyText.append(userCredentials.consumerKey);
            requestBodyText.append("&client_secret=");
            requestBodyText.append(userCredentials.consumerSecret);
            System.out.println("Response Body: "+requestBodyText.toString());
            StringEntity requestBody = new StringEntity(requestBodyText.toString());
            requestBody.setContentType("application/x-www-form-urlencoded");
            httpPost.setEntity(requestBody);
            httpPost.addHeader(prettyPrintHeader);
            
            //Make the request and store the result
            response = httpClient.execute(httpPost);
            
            //Parse the result if we were able to connect. 
            if (  response.getStatusLine().getStatusCode() == 200 ) {
                String response_string = EntityUtils.toString(response.getEntity());
                try {
                    JSONObject json = new JSONObject(response_string);
                    oauth2Response = new OAuth2Response(json);
                    System.out.println("JSON returned by response: +\n" + json.toString(1));
                } catch (JSONException je) {
                    je.printStackTrace();
                }  
                baseUri = oauth2Response.instance_url + REST_ENDPOINT + "/v" + userCredentials.apiVersion +".0";
                oauthHeader = new BasicHeader("Authorization", "OAuth " + oauth2Response.access_token);
                System.out.println("\nSuccessfully logged in to instance: " + baseUri);
            } else {
                System.out.println("An error has occured. Http status: " + response.getStatusLine().getStatusCode());
                System.out.println(getBody(response.getEntity().getContent()));
                System.exit(-1);
            }
        } catch (UnsupportedEncodingException uee) {
            uee.printStackTrace();
        } catch (IOException ioe) {
            ioe.printStackTrace();
        } catch (NullPointerException npe) {
            npe.printStackTrace();
        }
        return response;
    }

    /**
     * This method demonstrates 
     * - How to use HTTPGet and a constructed URI to retrieve data from Salesforce.
     * - Simple parsing of a JSON object. 
     */
    public void restGetExample() {
        System.out.println("\n_______________ Account QUERY _______________");
        try {
            //Set up the HTTP objects needed to make the request.
            HttpClient httpClient = new DefaultHttpClient();
            String uri = baseUri + "/query?q=SELECT+id+,+name+FROM+Account+limit+1";
            System.out.println("Query URL: " + uri);
            HttpGet httpGet = new HttpGet(uri);
            httpGet.addHeader(oauthHeader);
            httpGet.addHeader(prettyPrintHeader);
            
            // Make the request.
            HttpResponse response = httpClient.execute(httpGet);
            
            // Process the result
            int statusCode = response.getStatusLine().getStatusCode();
            if (statusCode == 200) {
                String response_string = EntityUtils.toString(response.getEntity());
                try {
                    JSONObject json = new JSONObject(response_string);
                    System.out.println("JSON result of Query:\n" + json.toString(1));                   
                    accountId = json.getJSONArray("records").getJSONObject(0).getString("Id");
                    System.out.println("accountId value is " + accountId);
                } catch (JSONException je) {
                    je.printStackTrace();
                }             
            } else {
                System.out.println("Query was unsuccessful. Status code returned is " + statusCode);
            }
        } catch (IOException ioe) {
            ioe.printStackTrace();
        } catch (NullPointerException npe) {
            npe.printStackTrace();
        }
    }

    /**
     * This method demonstrates 
     * - How to use HTTPPost and a constructed URI to insert data into Salesforce.
     * - Simple creation of a JSON object. 
     */
    public void restPostExample(String accountId) {
        System.out.println("\n_______________ Contact INSERT _______________");     
        String uri = baseUri + "/sobjects/Contact/";
        try {
            //create the JSON object containing the new contact details.
            JSONObject contact = new JSONObject();
            contact.put("LastName", "Polsani");
            contact.put("FirstName", "Kishore");
            contact.put("MobilePhone", "9999999999");
            contact.put("Phone", "9999999999");          
            contact.put("AccountId", accountId);
            System.out.println("JSON for contact record to be inserted:\n" + contact.toString(1));

            //Construct the objects needed for the request
            DefaultHttpClient httpClient = new DefaultHttpClient();
            HttpPost httpPost = new HttpPost(uri);
            httpPost.addHeader(oauthHeader);
            httpPost.addHeader(prettyPrintHeader);
            // The message we are going to post
            StringEntity body = new StringEntity(contact.toString(1));
            body.setContentType("application/json");
            httpPost.setEntity(body);

            //Make the request
            HttpResponse response = httpClient.execute(httpPost);

            //Process the results
            int statusCode = response.getStatusLine().getStatusCode();
            if (statusCode == 201) {
                String response_string = EntityUtils.toString(response.getEntity());
                JSONObject json = new JSONObject(response_string);
                // Store the retrieved contact id to use when we update the contact.
                contactId = json.getString("id");
                System.out.println("New contact id from response: " + contactId);         
            } else {
                System.out.println("Insertion unsuccessful. Status code returned is " + statusCode);
            }
        } catch (JSONException e) {
            System.out.println("Issue creating JSON or processing results");
            e.printStackTrace();
        } catch (IOException ioe) {
            ioe.printStackTrace();
        } catch (NullPointerException npe) {
            npe.printStackTrace();
        }
    }

    /**
     * This method demonstrates 
     * - How to use HTTPPatch and a constructed URI to update data in Salesforce.
     * NOTE: You have to create the HTTPPatch, as it does not exist in the standard library.
     * - Simple creation of a JSON object. 
     */ 
    public void restPatchExample(String contactid) {
        System.out.println("\n_______________ Contact UPDATE _______________");
        
        //Notice, the id for the record to update is part of the URI, not part of the JSON
        String uri = baseUri + "/sobjects/Contact/" + contactid;
        try {
            //Create the JSON object containing the updated contact phone number
            //and the id of the contact we are updating.
            JSONObject contact = new JSONObject();
            contact.put("Phone", "(415)555-1234");
            System.out.println("JSON for update of contact record:\n" + contact.toString(1));

            //Set up the objects necessary to make the request.
            DefaultHttpClient httpClient = new DefaultHttpClient();
            HttpPatch httpPatch = new HttpPatch(uri);
            httpPatch.addHeader(oauthHeader);
            httpPatch.addHeader(prettyPrintHeader);
            StringEntity body = new StringEntity(contact.toString(1));
            body.setContentType("application/json");
            httpPatch.setEntity(body);

            //Make the request
            HttpResponse response = httpClient.execute(httpPatch);

            //Process the response
            int statusCode = response.getStatusLine().getStatusCode();
            if (statusCode == 204) {
                System.out.println("Updated the contact successfully.");          
            } else {
                System.out.println("Contact update NOT successfully. Status code is " + statusCode);
            }
        } catch (JSONException e) {
            System.out.println("Issue creating JSON or processing results");
            e.printStackTrace();
        } catch (IOException ioe) {
            ioe.printStackTrace();
        } catch (NullPointerException npe) {
            npe.printStackTrace();
        }
    }

    /**
     * Extend the Apache HttpPost method to implement an HttpPost
     * method.
     */
    private static class HttpPatch extends HttpPost {
        public HttpPatch(String uri) {
            super(uri);
        }
        
        public String getMethod() {
            return "PATCH";
        }
    }

    /**
     * This class is used to hold values returned by the OAuth request.
     */
    static class OAuth2Response {
        String id;
        String issued_at;
        String instance_url;
        String signature;
        String access_token;

        public OAuth2Response() {
        }
        public OAuth2Response(JSONObject json) {
            try {
                id =json.getString("id");
                issued_at = json.getString("issued_at");
                instance_url = json.getString("instance_url");
                signature = json.getString("signature");
                access_token = json.getString("access_token");

            } catch (JSONException e) {
                e.printStackTrace();
            }
        }
    }

    //==========utility methods=============
    /**
     * Utility method for changing a stream into a String.
     * @param inputStream
     * @return
     */
    private String getBody(InputStream inputStream) {
        String result = "";
        try {
            BufferedReader in = new BufferedReader(
                    new InputStreamReader(inputStream)
            );
            String inputLine;
            while ( (inputLine = in.readLine() ) != null ) {
                result += inputLine;
                result += "\n";
            }
            in.close();
        } catch (IOException ioe) {
            ioe.printStackTrace();
        }
        return result;
    }

    //--------------utility methods for user input----------
    /**
     * A utility method to be used for getting user input from the console.
     */
    private String getUserInput(String prompt) {
        String result = "";
        try {
            System.out.print(prompt);
            result = reader.readLine();
        } catch (IOException ioe) {
            ioe.printStackTrace();
        }
        return result;
    }

    /**
     * Outputs menu choices on console.
     */
    private void showMenu() {
        System.out.println("");
        System.out.println("");
        System.out.println(" 1. Login Only");
        System.out.println(" 2. Find Account");
        System.out.println(" 3. Insert Contact for Account");
        System.out.println(" 4. Update Contact");
        System.out.println("99. Exit");
        System.out.println("   ");
    }
}

Create an Inbound Integration Using the Force.com REST API

Sample Project

Screenshots: