SMS and MMS Notifications with Java and Spring

January 10, 2017
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sms-mms-java-spring

Today we'll build a Java and Spring sample application which demonstrates how to push SMS alerts on server exceptions.  We'll show you how to automatically notify your server administrators when something goes wrong, and cover the plumbing that makes it happen.

Let's get started!

List the Server Administrators - or Whomever Else - to Notify

Here we create a JSON list of administrators and whomever else should be notified if a server exception occurs.

The only essential piece of data we need is a phoneNumber for each person.

This is a migrated tutorial. Clone the original from https://github.com/TwilioDevEd/server-notifications-spring/


  {
    "name": "Bob"

Next, let's take a look at how to configure the Twilio REST client.

Configuring the Twilio REST Client

To send a message we'll need to initialize the TwilioRestClient as documented in the Twilio Java Helper Library. It requires reading a TWILIO_ACCOUNT_SID and TWILIO_AUTH_TOKEN from environment variables.

The values for your Account SID and Authorization Token will come directly from the Twilio console:

Twilio Account Summary section of the console

Click the eyeball icon to expose your Auth Token in a form you can copy and paste.

package com.twilio.notifications.domain.twilio;

import com.twilio.http.TwilioRestClient;

public class Client {
    private Credentials credentials;
    private TwilioMessageCreator messageCreator;

    public Client() {
        this.credentials = new Credentials();
        this.messageCreator = new TwilioMessageCreator(
                new TwilioRestClient.Builder(credentials.getAccountSid(), credentials.getAuthToken()).build()
        );
    }

    public Client(TwilioMessageCreator messageCreator, Credentials credentials) {
        this.credentials = credentials;
        this.messageCreator = messageCreator;
    }

    public void sendMessage(String to, String message, String mediaUrl) {
        messageCreator.create(to, credentials.getPhoneNumber(), message, mediaUrl);
    }
}


Next, we will see how to handle application exceptions and add in our new functionality.

Handling the Application Exceptions

Spring MVC provides several techniques to handle errors but in this case we are interested in handling all our application exceptions on our own.

For catching everything, we can use Global Exception Handling.

package com.twilio.notifications.controller;

import com.twilio.notifications.domain.Administrator;
import com.twilio.notifications.domain.twilio.Client;
import com.twilio.notifications.service.AdministratorService;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.ResponseBody;

@ControllerAdvice
@SuppressWarnings("UnusedDeclaration")
public class GlobalExceptionController {
    @ExceptionHandler(Exception.class)
    @ResponseBody
    public String handleAllException(Exception ex) {
        String message = customMessage(ex.getMessage());
        String mediaUrl = "http://goo.gl/ObTXdX";

        // Send a message to the administrators when something goes unexpectedly wrong.
        Administrator[] administrators = new AdministratorService().getAdministrators();
        for (Administrator administrator : administrators) {
            new Client().sendMessage(administrator.getPhoneNumber(), message, mediaUrl);
        }

        return "Something unexpected happened. Keep calm, administrators were notified.";
    }

    private String customMessage(String exceptionMessage) {
        return String.format("It appears the server is having Exception: %s " +
                        "Go to: http://newrelic.com for more details. " +
                        "Image URL: http://goo.gl/ObTXdX",
                        exceptionMessage);
    }
}

Next up, let's see how to create a custom message.

Creating a Custom Alert Message

Here we craft the perfect alert message to send out via text message.

You might also decide to include a picture with your exception handling message. Perhaps a screenshot of the application when the crash happened?  Some infographics from somewhere?

package com.twilio.notifications.controller;

import com.twilio.notifications.domain.Administrator;
import com.twilio.notifications.domain.twilio.Client;
import com.twilio.notifications.service.AdministratorService;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.ResponseBody;

@ControllerAdvice
@SuppressWarnings("UnusedDeclaration")
public class GlobalExceptionController {
    @ExceptionHandler(Exception.class)
    @ResponseBody
    public String handleAllException(Exception ex) {
        String message = customMessage(ex.getMessage());
        String mediaUrl = "http://goo.gl/ObTXdX";

        // Send a message to the administrators when something goes unexpectedly wrong.
        Administrator[] administrators = new AdministratorService().getAdministrators();
        for (Administrator administrator : administrators) {
            new Client().sendMessage(administrator.getPhoneNumber(), message, mediaUrl);
        }

        return "Something unexpected happened. Keep calm, administrators were notified.";
    }

    private String customMessage(String exceptionMessage) {
        return String.format("It appears the server is having Exception: %s " +
                        "Go to: http://newrelic.com for more details. " +
                        "Image URL: http://goo.gl/ObTXdX",
                        exceptionMessage);
    }
}

Let's look at how to load the list of lucky administrators.

Reading the Administrators from the JSON File

Next we read the admins (and the other lucky folks) from our JSON file.

We use the Gson Java library to convert our JSON text file into Administrator objects from our application.

package com.twilio.notifications.service;


import com.google.gson.Gson;
import com.twilio.notifications.domain.Administrator;
import org.springframework.stereotype.Service;

import java.io.FileNotFoundException;
import java.io.FileReader;

@Service
public class AdministratorService {
    private String filePath;

    public AdministratorService() {
        this.filePath = getClass().getClassLoader().getResource("administrators.json").getPath();
    }

    public AdministratorService(String filePath) {
        this.filePath = filePath;
    }

    public Administrator[] getAdministrators() {
        try {
            return new Gson().fromJson(new FileReader(filePath), Administrator[].class);
        } catch (FileNotFoundException e) {
            e.printStackTrace();

            return new Administrator[0];
        }
    }
}


Next up, let's look at how to send a text message.

Sending a Text Message

There are three parameters needed to send an SMS using the Twilio REST API: From, To, and Body.

US and Canadian phone numbers can also send an image with the message.  Other countries can as well, but the image will be included in the message body as a shortened URL.

package com.twilio.notifications.domain.twilio;

import com.twilio.exception.TwilioException;
import com.twilio.http.TwilioRestClient;
import com.twilio.rest.api.v2010.account.Message;
import com.twilio.rest.api.v2010.account.MessageCreator;
import com.twilio.type.PhoneNumber;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class TwilioMessageCreator {

    private static final Logger logger = LoggerFactory.getLogger(TwilioMessageCreator.class);
    private final TwilioRestClient client;

    public TwilioMessageCreator(TwilioRestClient client) {
        this.client = client;
    }

    public void create(String to, String from, String body, String mediaUrl) {
        MessageCreator messageCreator = new MessageCreator(
                new PhoneNumber(to),
                new PhoneNumber(from),
                body);
        messageCreator.setMediaUrl(mediaUrl);
        try {
            messageCreator.create(this.client);
        } catch (TwilioException e) {
            logger.error(
                    "An exception occurred trying to send a message to {}, exception: {}",
                    to,
                    e.getMessage());
        }
    }
}


That's all, folks! 

We've just implemented an automated server notification system in Java and Spring that notifies all the right people when exceptions inevitably occur.

Now let's look at some other common features that are easy to add with the Java SDK.

Where to Next?

If you're a Java developer working with Twilio, you might want to check out these other tutorials.

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