---
title: Java Spark Starter
slug: java-spark-starter
published_at: 2021-03-09 18:00:14 +0000
updated_at: 2023-01-30 22:53:45 +0000
summary: 
description: In this edition of Stripe Developer Office Hours, follow along as CJ Avilla walks through the fundamentals of setting up a basic web application with Java Spark.  ## Resources  - Spark Framework https://sparkjava.com/ - curl command line tool https://curl.haxx.se/ - java-dotenv https://github.com/cdimascio/dotenv-java  - Stripe Webhooks Guide https://stripe.com/docs/webhooks/build - Stripe Event Types  https://stripe.com/docs/api/events/types - Code: https://github.com/stripe-samples/developer-office-hours/tree/master/starter/server/java  ### Presenter  CJ Avilla, Developer Advocate at Stripe - https://twitter.com/cjav_dev  ### Table of contents  00:00 Overview 01:50 Scaffold an HTML page 02:18 Setup the pom.xml file for installing dependencies with Maven 04:20 Create a new Server class 04:50 Make an API call to Stripe to list products 06:10 Setup .env for managing API keys 06:48 Install Java Spark 07:00 Serve static assets 07:36 Add a GET route server-side 09:00 Make GET request client-side 09:52 Add a POST route server-side 11:30 Make a POST request client-side 12:27 Setup a webhook handler 14:16 Recap  ### Support  If you have a question, please feel free to reach out to our support team at https://support.stripe.com/ or join us on Discord https://stripe.com/go/developer-chat.  ### Updates  Sign up to stay updated with developer news: https://go.stripe.global/dev-digest  ### Feedback  If you have any feedback about this or other episodes, let us know: https://forms.gle/VjNqzRhotM2snYo88. #Stripe #Payments
tags: [java spark, Java Spark Starter, Java Spark Basics, Stripe, Payments, stripe-java, Stripe Java, How to setup a Java Spark server, Getting started with Java Spark, Java Spark Introduction, Introduction to Java Spark, Java, Spark, Spark Framework, @cjav_dev]
views: 945
author: CJ Avilla
url: https://www.cjav.dev/videos/java-spark-starter
youtube_url: https://www.youtube.com/watch?v=qY2HBiBu2XA
youtube_id: qY2HBiBu2XA
embed_url: https://www.youtube.com/embed/qY2HBiBu2XA
thumbnail_url: https://i.ytimg.com/vi/qY2HBiBu2XA/hqdefault.jpg
type: video
---

# Java Spark Starter

*Published: March 09, 2021*
*Views: 945*

## Watch

[Watch on YouTube](https://www.youtube.com/watch?v=qY2HBiBu2XA)

[![Java Spark Starter](https://i.ytimg.com/vi/qY2HBiBu2XA/hqdefault.jpg)](https://www.youtube.com/watch?v=qY2HBiBu2XA)

## Description

In this edition of Stripe Developer Office Hours, follow along as CJ Avilla walks through the fundamentals of setting up a basic web application with Java Spark.

## Resources

- Spark Framework https://sparkjava.com/
- curl command line tool https://curl.haxx.se/
- java-dotenv https://github.com/cdimascio/dotenv-java 
- Stripe Webhooks Guide https://stripe.com/docs/webhooks/build
- Stripe Event Types  https://stripe.com/docs/api/events/types
- Code: https://github.com/stripe-samples/developer-office-hours/tree/master/starter/server/java

### Presenter

CJ Avilla, Developer Advocate at Stripe - https://twitter.com/cjav_dev

### Table of contents

00:00 Overview
01:50 Scaffold an HTML page
02:18 Setup the pom.xml file for installing dependencies with Maven
04:20 Create a new Server class
04:50 Make an API call to Stripe to list products
06:10 Setup .env for managing API keys
06:48 Install Java Spark
07:00 Serve static assets
07:36 Add a GET route server-side
09:00 Make GET request client-side
09:52 Add a POST route server-side
11:30 Make a POST request client-side
12:27 Setup a webhook handler
14:16 Recap

### Support

If you have a question, please feel free to reach out to our support team at https://support.stripe.com/ or join us on Discord https://stripe.com/go/developer-chat.

### Updates

Sign up to stay updated with developer news: https://go.stripe.global/dev-digest

### Feedback

If you have any feedback about this or other episodes, let us know: https://forms.gle/VjNqzRhotM2snYo88.
#Stripe #Payments

## Transcript

[Music] in this episode we cover foundational topics and dig into the basics of using the java spark web framework how it works and how we use spark when creating video tutorials like this one and also in the stripe samples which is a collection of github repositories demonstrating integrations with many stripe products so you may be just getting started and are curious how to build an application from scratch to take your first online payment so if you already have a back-end set up and are comfortable adding new routes and are looking just to add a new stripe integration you might want to check out the other videos on this channel where we show how to integrate specific stripe products and features so why why spark the javaspark framework in its own words is a micro framework for creating web applications in kotlin and java 8 with minimal effort so it's simple and expressive and really built for productivity this allows us to keep the code for a demo concise while also showing a working example so if your app is written with a more feature-rich web framework like spring jsf gwt the same fundamentals are going to apply but you know it's going to be implemented a little differently across those bigger more opinionated code bases so it might be helpful to watch and refer to two other videos before watching this one first one about managing environment variables with java and the second being an introduction to the stripe cli so we'll have links in the description to these and other helpful resources so as a quick agenda for today we're going to cover how to set up a simple client with html we'll show you how to test out that stripe java is installed and that your api keys are working uh we'll talk about how to add a get route in a post route and you also learn how to set up a basic post route to use as your web hook handler so to start we're going to create a client and server directory the client will have a single html file and the server will contain our palm.xml and server.java so here we're going to make a new directory for the client and for the server we're going to use this big class path all right let's jump right in and add some basic html in index.html and we'll add some rough structure and just a helper css file in almost all stripe samples or video tutorials for the web we'll install stripe.js note that you always want to load stripe.js directly from js.stripe.com don't self-host this so in some cases we'll write frontend javascript directly in line to keep the content front and center in other cases we might use a script tag to just include a javascript file in our project so we're going to need an instance of the stripe object on the client in order to work with stripe.js which we can do by calling this constructor function and passing in our publishable key now after signing up for an account you can find your api keys in the stripe dashboard it's fine for purely web-based projects to hard code your publishable key directly on the client but if you're working with mobile applications it's recommended to fetch your publishable key from the server so that versions of your mobile application aren't tied to specific publishable keys just in case you need to roll those so as just an example for how to make a get request to fetch some data from the server we'll request the publishable key and then set it right here in a bit so we'll meet back here in a few minutes all right so let's turn to our back end and in this episode we'll manually create the project object model the palm.xml file and this file defines all the config for the build process and also where we'll manage dependencies if you're working with an ide like intellij or eclipse this palm.xml is typically managed for you when using the ui to like add dependencies and configure your project and give it a name and such but we're going to be editing this as text so we have full control and visibility into those changes all right so we'll start from this very minimal palm.xml file and we'll build up from here you'll notice that at the top of the file we see some basic config about the project with its name and version etc then a list of dependencies and finally some build configuration of note we'll specify the main class as server and configuration with a predefined plugin descriptor for with descriptor ref for jar with dependencies so that our jar output file has all of our dependencies built in now we can package our jar file with maven package but first we're going to need to implement a basic class with an entry point for running our app so let's open server.java and dive in we'll add a server class with a main function as our entry point here and just a little print statement okay let's build with maven package and try to run this so we're going to say java cp and then we're going to specify a target which is going to be this jar with dependencies and then we pass it the name of the class so com.stripe.sample.server cool all right so let's make sure that we can make api requests with stripe java by making a simple api call to list some products my demo account here already has several products set up in the stripe dashboard that will be returned from the api if this works we'll import stripe and a couple models that are required for fetching a list of products then set our api key and just make a get request to the stripe api using stripe java to fetch those products and we'll just print it out cool so let's repackage and again run the program to see the output awesome so we can see this json was returned from the stripe api so we know our api keys and stripe java are working as expected now in practice we don't want to hard code our api keys here so you might already have some credentials management tool for stripe samples and videos we tend to use dot end files for storing environment variables and managing api keys we have an episode all about managing environment variables with dot end and with java that we'll link to in the description now to load our api key from end we use a package called java.end so let's add that dependency to our palm.xml and then import it and now we can load the.n file with end.load and retrieve with dot end dot get now in order for this to work we actually need a dot end file in the server directory with the api keys so let's create one of those now and to start we're just going to add our secret and publishable keys now when you're working with stripe samples editing this dot n file and getting it set up is the biggest thing that trips people up so be sure this file exists it's called dot end and it has some good values populated there's typically a dot m dot example or dot end dot sample somewhere in the sample repository if we repackage and run the application that will confirm that our end file is working as expected and still hitting the stripe api with our secret keys again we're seeing some json back from stripe so things are looking good so let's add the spark web framework and get a basic server running so the way we use spark it has two dependencies one is spark core and the other is for logging so we'll add those to palm.xml and then import some very basic tools for spark so that we can just start with rendering some static assets so we're going to tell static files where to find the client-side code with index.html that we wrote earlier technically this client directory might differ a little depending on whether the sample is installed with git so just like git cloning the entire repository or with stripe cli so we tend to load this path from environment variables and again managing with dot end okay cool so next let's add a simple get route we'll need to import the get method from spark and that'll allow us to create a new route below with a call to get where we pass as the first argument the path and then as the second argument a lambda expression that will be executed as our callback when the server receives a get request to slash public keys technically we want to render some json back with publishable key when working with json we use google's json library for serializing and deserializing so first again we're going to need that to add that as a dependency to palm.xml and then import the top level json class and the serialized name annotation which allows us to specify when a member should be serialized to json with the provided name value as its field name this works also for deserializing so we'll use this when we create classes for serializing and deserializing requests and responses cool all right so next we're going to create a static instance of json client that we're going to use for serializing and deserializing these requests and responses and in our route we'll specify that the response type is application json and then we're just going to create a simple hash map with our publishable key and serialize that out as json for the for the response so we can test our endpoint with curl to confirm that it's running and is returning well form json okay cool so we can uh we can access this server data also from the front end now with javascript so let's head back over to the front end and we're going to use the browser's built-in fetch method for making an ajax request to this new endpoint so when using fetch to make a get request we can simply pass the path or the full url to which we want to send that request and it will return a promise that resolves with an object that has a json method which also in turn responds with a returns a promise that will ultimately resolve with the json object returned from the server so from the browser we can open the developer tools and look at the sources tab where we can see the frontend code that's actually executing i like to add breakpoints by clicking on a line number in the gutter and then hovering over various objects to see what their values are at various points you can use these buttons on the right here to step through or continue execution with that play button alright so this looks great and shows us how to make a get request from the browser back to our server next let's go add a new route to the server that'll accept post requests with data from the front end passed in from the front end so again we're going to use the same type of route this time it's going to be a post route so we're going to match on and pass in the path for accepting this post route and this is going to be create customer now most samples are going to pass json from the front end and that'll be deserialized into an object that we can more easily work with so let's create a static class which we'll deserialize into with json for now we're just going to keep the structure of the request very simple and just accept the email value in the json post body again this like serialized name attribute allows us to specify the value for the name property for the incoming or for the incoming json so we could name this email with a capital e or we could name it uh you know whatever if we want to use snake case or you know camel case here we could do that with serialized name next we're going to deserialize the request body into an object that we can print and work with okay poking at this endpoint with curl and making a post request with the email in the body of the request notice that the endpoint is just echoing back the request body so in practice this could be passing back an id for a newly created object or a database record or we could be creating a striped customer here and then storing its id in the database and replying with whatever you know the database records ideas all right so finally let's let's learn how to make this post request from the front end back to this api endpoint so that we can pass data collected from the customers to our server so we'll collect the email with an input and add a button for submitting the data let's grab reference to that button and add a click handler and what we want to do is when the button is clicked we want to send a post request again using this built-in fetch method available in the browser but this time we need to specify that it's a post request and we're sending application json now the data we're sending back is this json object where we can specify the value for the email like so so we're going to pull the email out of the email input and pass its value now when we click the button the email is passed to the server and we can see that jennyrosen.example.com in the alert and in the server log so to wrap up our basic sample we're going to add one more route for handling web hook notifications in this case we're receiving post requests directly from stripe so we have episodes all about how to work with web hook helpers so head over to the stripe developers channel to see those in action we'll start by referring directly to the stripe documentation here for web hook so we're going to go to stripe.com docs web hooks slash build and from here we'll copy the java snippet for webhooks and we'll just paste that into our our post our new post route which is going to accept post requests to slash webhooks and now we can talk through each of these bits so the first half of this function is basically to safely read in the request body and deserialize it into a stripe event object note that you could technically use the json instance here when creating we created earlier rather than the one that's on api resource if you wanted now each event has the same high level structure where we'll include some inner object and that inner object is going to vary based on the type of the event so because the underlying object could be a payment intent or a customer or really any type of stripe resource we need to further deserialize that raw inner json into some intermediate generic stripe object so that we can cast that into the specific stripe java model below that way we can access methods on the object itself and you know if the request was read successfully and the event was deserialized without error then we can sort of just like switch on the events type and automate logic for things like pulling from inventory sending customer emails printing shipping labels etc okay and then finally we respond with a 200 status code back to stripe all right so as a quick recap we scaffolded a basic html page showed how to serve some static files and exposed get and post routes from a spark server we also covered how to make get and post requests from the front end using the browser's built-in fetch command this is how the starter was built and how we build samples with java and the spark framework thanks so much for watching if you're interested in seeing more content like this or to help build and maintain your stripe integration consider subscribing and liking this video so you'll be notified of future episodes it also helps others find this content so if you have any feedback for us please let us know in the feedback form linked in the description and otherwise we'll see in the next one [Music] you

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