Review

In the previous section, we have learned how to sign-up with SendGrid's free plan. In this section, we will start writing the Java classes and discuss the project's structure.

Part 1: Introduction and Functional Specs
Part 2: SendGrid account setup
Part 3: Java classes
Part 4: XML configuration
Part 5: Running the Application

Project Structure

Our application is a Maven project which means our project follows the Maven structure.

Here's a preview of our project's structure:

Domain Layer

The domain layer contains a Message class that represents an email message.

	package org.krams.domain;

	import java.io.Serializable;

	public class Message implements Serializable {

	private static final long serialVersionUID = -4093981756240899937L;
	private String senderName;
	private String senderEmail;
	private String ccEmail;
	private String subject;
	private String body;
	private String receiverName;
	private String receiverEmail;

	public Message() {
	super();
	}

	public Message(String senderName, String senderEmail, String ccEmail,
	String subject, String body, String receiverName,
	String receiverEmail) {
	super();
	this.senderName = senderName;
	this.senderEmail = senderEmail;
	this.ccEmail = ccEmail;
	this.subject = subject;
	this.body = body;
	this.receiverName = receiverName;
	this.receiverEmail = receiverEmail;
	}

	...getters/setters
	}

view raw Message.java hosted with ❤ by GitHub

Controller Layer

The controller layer contains a simple controller that serves a form for composing and sending emails. It also contains a send method that accepts a Message object. The controller delegates the sending part to an email service.

	package org.krams.controller;

	import org.krams.domain.Message;
	import org.krams.response.StatusResponse;
	import org.krams.service.EmailService;
	import org.springframework.beans.factory.annotation.Autowired;
	import org.springframework.stereotype.Controller;
	import org.springframework.web.bind.annotation.RequestBody;
	import org.springframework.web.bind.annotation.RequestMapping;
	import org.springframework.web.bind.annotation.RequestMethod;
	import org.springframework.web.bind.annotation.ResponseBody;

	@Controller
	@RequestMapping("/email")
	public class EmailController {

	@Autowired
	private EmailService emailService;

	@RequestMapping
	public String form() {
	return "form";
	}

	@RequestMapping(value ="/send", method=RequestMethod.POST)
	public @ResponseBody StatusResponse send(@RequestBody Message message) {
	return emailService.send(message);
	}
	}

view raw EmailController.java hosted with ❤ by GitHub

Service Layer

The service layer contains the email service. We have a simple interface EmailService for sending messages.

	package org.krams.service;

	import org.krams.domain.Message;
	import org.krams.response.StatusResponse;

	public interface EmailService {
	StatusResponse send(Message message);
	}

view raw EmailService.java hosted with ❤ by GitHub

The actual implementation SendGridEmailService relies on RestTemplate to send the email message via HTTP as a POST method.

	package org.krams.service;

	import org.apache.log4j.Logger;
	import org.krams.domain.Message;
	import org.krams.response.StatusResponse;
	import org.krams.util.SendGridParameter;
	import org.springframework.beans.factory.annotation.Value;
	import org.springframework.stereotype.Service;
	import org.springframework.util.LinkedMultiValueMap;
	import org.springframework.util.MultiValueMap;
	import org.springframework.web.client.RestTemplate;

	@Service
	public class SendGridEmailService implements EmailService {

	protected static Logger logger = Logger.getLogger("service");
	private RestTemplate restTemplate = new RestTemplate();

	@Value("${sendgrid.api.user}")
	private String sendgridApiUser;

	@Value("${sendgrid.api.key}")
	private String sendgridApiKey;

	@Override
	public StatusResponse send(Message message) {
	try {
	MultiValueMap<String, Object> vars = new LinkedMultiValueMap<String, Object>();
	vars.add(SendGridParameter.API_USER, sendgridApiUser);
	vars.add(SendGridParameter.API_KEY, sendgridApiKey);
	vars.add(SendGridParameter.SENDER_NAME, message.getSenderName());
	vars.add(SendGridParameter.SENDER_EMAIL, message.getSenderEmail());
	vars.add(SendGridParameter.BLIND_COPY_EMAIL, message.getCcEmail());
	vars.add(SendGridParameter.SUBJECT, message.getSubject());
	vars.add(SendGridParameter.TEXT, "");
	vars.add(SendGridParameter.HTML, message.getBody());
	vars.add(SendGridParameter.RECEIVER_EMAIL, message.getReceiverEmail());
	vars.add(SendGridParameter.RECEIVER_NAME, message.getReceiverName());

	restTemplate.postForLocation(SendGridParameter.URL, vars);
	} catch (Exception ex) {
	logger.error(ex);
	return new StatusResponse(false, "An error has occurred!");
	}

	return new StatusResponse(true, "Message sent");
	}


	}

view raw SendGridEmailService.java hosted with ❤ by GitHub

Utility Layer

This layer contains helper classes and interfaces. Here we've extracted the required SendGrid parameters for sending emails via HTTP. Please refer to Part 2 of this guide if you need to review the SendGrid Web API.

	package org.krams.util;

	public interface SendGridParameter {
	public static final String URL = "http://sendgrid.com/api/mail.send.json";
	public static final String API_USER = "api_user";
	public static final String API_KEY = "api_key";
	public static final String RECEIVER_EMAIL = "to";
	public static final String RECEIVER_NAME = "toname";
	public static final String SUBJECT = "subject";
	public static final String TEXT = "text";
	public static final String HTML = "html";
	public static final String SENDER_EMAIL = "from";
	public static final String SENDER_NAME = "fromname";
	public static final String BLIND_COPY_EMAIL = "bcc";
	}

view raw SendGridParameter.java hosted with ❤ by GitHub

View Layer

The view layer contains a simple html form for composing and sending email messages. One important section here that needs to be discussed is the usage of the postJSON plugin.

	<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>

	<c:url value="/email/send" var="sendUrl"/>

	<html>
	<head>
	<link rel="stylesheet" type="text/css" media="screen" href='<c:url value="/resources/css/jquery-ui/pepper-grinder/jquery-ui-1.8.16.custom.css"/>'/>
	<link rel="stylesheet" type="text/css" media="screen" href='<c:url value="/resources/css/style.css"/>'/>
	<script type='text/javascript' src='<c:url value="/resources/js/jquery-1.6.4.min.js"/>'></script>
	<script type='text/javascript' src='<c:url value="/resources/js/jquery-ui-1.8.16.custom.min.js"/>'></script>
	<script type='text/javascript' src='<c:url value="/resources/js/util.js"/>'></script>

	<title>Email</title>

	<script type='text/javascript'>
	$(function() {
	init();
	});

	function init() {
	$('input:button').button();
	$('#submit').button();

	$('#emailForm').submit(function() {
	event.preventDefault();

	$.postJSON('${sendUrl}', {
	senderName: $('#senderName').val(),
	senderEmail: $('#senderEmail').val(),
	ccEmail: $('#ccEmail').val(),
	subject: $('#subject').val(),
	body: $('#textBody').val(),
	receiverName: $('#receiverName').val(),
	receiverEmail: $('#receiverEmail').val()
	},
	function(result) {
	if (result.success == true) {
	dialog('Success', 'Email has been sent!');
	} else {
	dialog('Failure', 'Email has not been sent!');
	}
	});
	});

	$('#reset').click(function() {
	clearForm();
	dialog('Success', 'Fields have been cleared!');
	});
	}

	function dialog(title, text) {
	$('#msgbox').text(text);
	$('#msgbox').dialog(
	{ title: title,
	modal: true,
	buttons: {"Ok": function() {
	$(this).dialog("close");}
	}
	});
	}

	function clearForm() {
	$('#receiverName').val('');
	$('#receiverEmail').val('');
	$('#ccEmail').val('');
	$('#senderName').val('');
	$('#senderEmail').val('');
	$('#subject').val('');
	$('#textBody').val('');
	}
	</script>
	</head>

	<body>
	<h1 id='banner'>Compose Email</h1>

	<div>
	<form id='emailForm'>
	<fieldset>
	<legend>New Email</legend>
	<label for='receiverName'>To (name):</label><input type='text' id='receiverName'/><br/>
	<label for='receiverEmail'>To (email)</label><input type='text' id='receiverEmail'/><br/>
	<label for='ccEmail'>Cc (email):</label><input type='text' id='ccEmail'/><br/>
	<label for='senderName'>From (name):</label><input type='text' id='senderName'/><br/>
	<label for='senderEmail'>From (email):</label><input type='text' id='senderEmail'/><br/>
	<label for='subject'>Subject:</label><input type='text' id='subject'/><br/>
	<label for='textBody' style="display:break">Message</label>
	<textarea name="textBody" id="textBody">Email message here</textarea><br/>
	<input type='button' value='Reset' id='reset' />
	<input type='submit' value='Send' id='submit'/>
	</fieldset>
	</form>
	</div>

	<div id='msgbox' title='' style='display:none'></div>
	</body>
	</html>

view raw form.jsp hosted with ❤ by GitHub

jQuery plugin

postJSON is a jQuery plugin that allows sending of JSON objects via POST. This plugin is based a plugin I found at the jQuery plugin repository. Unfortunately, the location doesn't seem to exist anymore. Also, I've made some modifications with the plugin (see the comments).

	/*************************************************
	* Source: http://plugins.jquery.com/project/postJSON
	* Modifications:
	* a. Replace json to jsonData
	* b. Replace success to callbackSuccess
	*
	* Function: $.postJSON ( url, jsonObject, success, options )
	* url: The url to post the json object to
	* jsonObject: The JSON object to post
	* success: The success handler to invoke on successful submission
	* options: Additional options to provide to the AJAX call. This is the exact same object you would use when calling $.ajax directly.
	*
	* Description:
	* $.postJSON simplifies posting JSON objects to any url by invoking $.ajax with the required options. The specified JSON object will be stringified and posted to the url.
	* It's up to the server to deserialize the stringified JSON object. ASP.NET MVC 3 will do this automatically
	*
	* Sample usage:
	* var onSuccess = function() { ... };
	* var onError = function() { ... };
	* $.postJSON ( '/account/login', { username: 'jack', password: 'secretPass' }, onSuccess, { error: onError } );
	**************************************************/
	(function ($) {
	$.extend({
	postJSON: function (url, jsonData, callbackSuccess, options) {
	var config = {
	url: url,
	type: "POST",
	data: jsonData ? JSON.stringify(jsonData) : null,
	dataType: "json",
	contentType: "application/json; charset=utf-8",
	success: callbackSuccess
	};

	// $.ajax($.extend(options, config)); // only works for jQuery 1.4+
	$.ajaxSetup(config); // only works for jQuery 1.5+
	$.ajax();

	// reset back so that future users aren't affected
	config = {
	url: null,
	type: "GET",
	data: null,
	dataType: null,
	contentType: "application/x-www-form-urlencoded",
	success: null
	};
	$.ajaxSetup(config);
	}
	});
	})(jQuery);