Java Library for The Stripe API

Stripe Java client library

The official Stripe Java client library.

Installation

Requirements

  • Java 1.8 or later

Gradle users

Add this dependency to your project's build file:

implementation "com.stripe:stripe-java:20.128.0"

Maven users

Add this dependency to your project's POM:

<dependency>
  <groupId>com.stripe</groupId>
  <artifactId>stripe-java</artifactId>
  <version>20.128.0</version>
</dependency>

Others

You'll need to manually install the following JARs:

ProGuard

If you're planning on using ProGuard, make sure that you exclude the Stripe client library. You can do this by adding the following to your proguard.cfg file:

-keep class com.stripe.** { *; }

Documentation

Please see the Java API docs for the most up-to-date documentation.

See video demonstrations covering how to use the library.

You can also refer to the online Javadoc.

Usage

StripeExample.java

import java.util.HashMap;
import java.util.Map;

import com.stripe.Stripe;
import com.stripe.exception.StripeException;
import com.stripe.model.Customer;
import com.stripe.net.RequestOptions;
import com.stripe.param.CustomerCreateParams;

public class StripeExample {

    public static void main(String[] args) {
        Stripe.apiKey = "sk_test_...";
        
        CustomerCreateParams params =
            CustomerCreateParams
                .builder()
                .setDescription("Example description")
                .setEmail("test@example.com")
                .setPaymentMethod("pm_card_visa")  // obtained via Stripe.js
                .build();

        try {
            Customer customer = Customer.create(params);
            System.out.println(customer);
        } catch (StripeException e) {
            e.printStackTrace();
        }
    }
}

See the project's functional tests for more examples.

Per-request Configuration

All of the request methods accept an optional RequestOptions object. This is used if you want to set an idempotency key, if you are using Stripe Connect, or if you want to pass the secret API key on each method.

RequestOptions requestOptions = RequestOptions.builder()
    .setApiKey("sk_test_...")
    .setIdempotencyKey("a1b2c3...")
    .setStripeAccount("acct_...")
    .build();

Customer.list(null, requestOptions);

Customer.retrieve("cus_123456789", requestOptions);

Configuring automatic retries

The library can be configured to automatically retry requests that fail due to an intermittent network problem or other knowingly non-deterministic errors. This can be enabled globally:

Stripe.setMaxNetworkRetries(2);

Or on a finer grain level using RequestOptions:

RequestOptions options = RequestOptions.builder()
    .setMaxNetworkRetries(2)
    .build();
Customer.create(params, options);

Idempotency keys are added to requests to guarantee that retries are safe.

Configuring Timeouts

Connect and read timeouts can be configured globally:

Stripe.setConnectTimeout(30 * 1000); // in milliseconds
Stripe.setReadTimeout(80 * 1000);

Or on a finer grain level using RequestOptions:

RequestOptions options = RequestOptions.builder()
    .setConnectTimeout(30 * 1000) // in milliseconds
    .setReadTimeout(80 * 1000)
    .build();
Customer.create(params, options);

Please take care to set conservative read timeouts. Some API requests can take some time, and a short timeout increases the likelihood of a problem within our servers.

Configuring DNS Cache TTL

We cannot guarantee that the IP address of the Stripe API will be static. Commonly, default JVM configurations can have their DNS cache TTL set to forever. If Stripe's IP address changes, your application's requests to Stripe will all fail until the JVM restarts. Therefore we recommend that you modify the JVM's networkaddress.cache.ttl property to 60 seconds.

Writing a plugin

If you're writing a plugin that uses the library, we'd appreciate it if you identified using Stripe.setAppInfo():

Stripe.setAppInfo("MyAwesomePlugin", "1.2.34", "https://myawesomeplugin.info");

This information is passed along when the library makes calls to the Stripe API.

Request latency telemetry

By default, the library sends request latency telemetry to Stripe. These numbers help Stripe improve the overall latency of its API for all users.

You can disable this behavior if you prefer:

Stripe.enableTelemetry = false;

Development

JDK 18 is required to build the Stripe Java library. By default, tests use the same Java runtime as the build. To use a custom version of Java runtime for tests set the JAVA_TEST_HOME environment variable to runtime's home directory.

The test suite depends on stripe-mock, so make sure to fetch and run it from a background terminal (stripe-mock's README also contains instructions for installing via Homebrew and other methods):

go get -u github.com/stripe/stripe-mock
stripe-mock

To run all checks (tests and code formatting):

./gradlew check

To run the tests:

./gradlew test

You can run particular tests by passing --tests Class#method. Make sure you use the fully qualified class name. For example:

./gradlew test --tests com.stripe.model.AccountTest
./gradlew test --tests com.stripe.functional.CustomerTest
./gradlew test --tests com.stripe.functional.CustomerTest.testCustomerCreate

The library uses Spotless along with google-java-format for code formatting. Code must be formatted before PRs are submitted, otherwise CI will fail. Run the formatter with:

./gradlew spotlessApply

The library uses Project Lombok. While it is not a requirement, you might want to install a plugin for your favorite IDE to facilitate development.

Download Details:
Author: stripe
Source Code: https://github.com/stripe/stripe-java
License: MIT license

#java #Financial

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Java Library for The Stripe API
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How to Validate an Email Address in Java

Email is one of the most universal tools for sharing and receiving information across the globe, with users able to connect with others online with almost no compatibility or access issues. Using this tool, information can be instantly and securely sent to partners on the other side of the world, and personal information can be verified without divulging sensitive data about a user.

Along with this widespread use, however, comes key security measures that must take place in order to ensure the safety of your organization and data. This is particularly the case when receiving email information from previously unknown sources. These risks can include phishing attempts, malware, and other threats that can cause a negative impact to your business. Furthermore, when receiving an email address via account forms and user sign up information, you need to check that the information you are given is not only correct and real, but also that it does not lead to any malicious sources that could harm your organizational security.

The following APIs will allow you to instantly verify and validate an input email address without sending any kind of notification to the email user. This will help protect your organization in the event of any threats. The goal of this tutorial is to provide you with the tools to protect your organization’s information while providing a way to verify new accounts and user information.

This will be done through three separate functions. The first will analyze the validity of an email address’ syntax. The second will check for the address’ servers, and the third performs a full email address validation including returning the results for the previous two functions.

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How to Convert ODT Files to PDF in Java

Convert Office Open Document Text File (ODT) to standard PDF, DOCX, PNG, and JPG using Java.

Microsoft has maintained its position in the spotlight for formatted document creation and editing for good reason. Its extreme ease of use and lack of a learning curve has transformed the Microsoft Office Suite into a household name for most computer users in the United States as well as globally. This is propagated further through its almost ubiquitous use in education, as students are raised and taught using these applications.

The issue that arises with these programs, however, is their operation costs. For Apple and other non-Windows-based Operating Systems, the purchasing fees for Office can be steep. This, then, creates a paywall separating potential users from programs to which they are already accustomed. As an answer this problem, Microsoft created the OpenOffice application, which is a free, opensource version of the classic Office Suite. Within this application, you can perform almost all of the same functions as Office Suite, including creating text documents like one would with Microsoft Word. These text documents can be made using OpenOffice Writer, and are formatted using the .ODT file type. While this file type can be opened and saved using OpenOffice Writer and Word, in order to convert the file to a different format such as PDF you will need to run it through a conversion process.

The following APIs will allow you to convert your ODT documents to PDF, DOCX, PNG, and JPG for use in whatever way you need. The goal of this tutorial is to provide a simple and efficient means for instantly converting your ODT files without needing to find or download any extraneous programming.

#java #tutorial #api #pdf #java api #pdf converter #api access keys #api tutorial #java api tutorials #java apis

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How to Install OpenJDK 11 on CentOS 8

What is OpenJDK?

OpenJDk or Open Java Development Kit is a free, open-source framework of the Java Platform, Standard Edition (or Java SE). It contains the virtual machine, the Java Class Library, and the Java compiler. The difference between the Oracle OpenJDK and Oracle JDK is that OpenJDK is a source code reference point for the open-source model. Simultaneously, the Oracle JDK is a continuation or advanced model of the OpenJDK, which is not open source and requires a license to use.

In this article, we will be installing OpenJDK on Centos 8.

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How to Create a Barcode Image in Java

The following five APIs will allow you to create barcode images in the three previously mentioned formats.

Barcodes are used universally in commerce and retail to aid in tracking, purchasing, and inventory. This allows organizations to keep accurate records of their supplies, products, and other items that are pivotal to their operations. For international and national use, there are different barcodes that are utilized for specific contexts. For example, UPC and EAN barcodes look similar in their formatting and can be used in similar ways, but UPC is a largely North American coding system; however, both UPC and EAN are used globally. QR Codes are also used globally but are usually employed for sharing complex sets of information like item details or website links.

The following five APIs will allow you to create barcode images in the three previously mentioned formats. This will allow you to print or create packaging with your personal barcodes attached, without needing to retrieve it from an outside source. This can be especially useful for small businesses as it provides increased independence as a company and improved visual, professional appeal for your products.

#java #tutorial #api #java api #qr code #api access keys #java api tutorials #barcode generator #api tutorials #barcode api

Top 10 API Security Threats Every API Team Should Know

As more and more data is exposed via APIs either as API-first companies or for the explosion of single page apps/JAMStack, API security can no longer be an afterthought. The hard part about APIs is that it provides direct access to large amounts of data while bypassing browser precautions. Instead of worrying about SQL injection and XSS issues, you should be concerned about the bad actor who was able to paginate through all your customer records and their data.

Typical prevention mechanisms like Captchas and browser fingerprinting won’t work since APIs by design need to handle a very large number of API accesses even by a single customer. So where do you start? The first thing is to put yourself in the shoes of a hacker and then instrument your APIs to detect and block common attacks along with unknown unknowns for zero-day exploits. Some of these are on the OWASP Security API list, but not all.

Insecure pagination and resource limits

Most APIs provide access to resources that are lists of entities such as /users or /widgets. A client such as a browser would typically filter and paginate through this list to limit the number items returned to a client like so:

First Call: GET /items?skip=0&take=10 
Second Call: GET /items?skip=10&take=10

However, if that entity has any PII or other information, then a hacker could scrape that endpoint to get a dump of all entities in your database. This could be most dangerous if those entities accidently exposed PII or other sensitive information, but could also be dangerous in providing competitors or others with adoption and usage stats for your business or provide scammers with a way to get large email lists. See how Venmo data was scraped

A naive protection mechanism would be to check the take count and throw an error if greater than 100 or 1000. The problem with this is two-fold:

  1. For data APIs, legitimate customers may need to fetch and sync a large number of records such as via cron jobs. Artificially small pagination limits can force your API to be very chatty decreasing overall throughput. Max limits are to ensure memory and scalability requirements are met (and prevent certain DDoS attacks), not to guarantee security.
  2. This offers zero protection to a hacker that writes a simple script that sleeps a random delay between repeated accesses.
skip = 0
while True:    response = requests.post('https://api.acmeinc.com/widgets?take=10&skip=' + skip),                      headers={'Authorization': 'Bearer' + ' ' + sys.argv[1]})    print("Fetched 10 items")    sleep(randint(100,1000))    skip += 10

How to secure against pagination attacks

To secure against pagination attacks, you should track how many items of a single resource are accessed within a certain time period for each user or API key rather than just at the request level. By tracking API resource access at the user level, you can block a user or API key once they hit a threshold such as “touched 1,000,000 items in a one hour period”. This is dependent on your API use case and can even be dependent on their subscription with you. Like a Captcha, this can slow down the speed that a hacker can exploit your API, like a Captcha if they have to create a new user account manually to create a new API key.

Insecure API key generation

Most APIs are protected by some sort of API key or JWT (JSON Web Token). This provides a natural way to track and protect your API as API security tools can detect abnormal API behavior and block access to an API key automatically. However, hackers will want to outsmart these mechanisms by generating and using a large pool of API keys from a large number of users just like a web hacker would use a large pool of IP addresses to circumvent DDoS protection.

How to secure against API key pools

The easiest way to secure against these types of attacks is by requiring a human to sign up for your service and generate API keys. Bot traffic can be prevented with things like Captcha and 2-Factor Authentication. Unless there is a legitimate business case, new users who sign up for your service should not have the ability to generate API keys programmatically. Instead, only trusted customers should have the ability to generate API keys programmatically. Go one step further and ensure any anomaly detection for abnormal behavior is done at the user and account level, not just for each API key.

Accidental key exposure

APIs are used in a way that increases the probability credentials are leaked:

  1. APIs are expected to be accessed over indefinite time periods, which increases the probability that a hacker obtains a valid API key that’s not expired. You save that API key in a server environment variable and forget about it. This is a drastic contrast to a user logging into an interactive website where the session expires after a short duration.
  2. The consumer of an API has direct access to the credentials such as when debugging via Postman or CURL. It only takes a single developer to accidently copy/pastes the CURL command containing the API key into a public forum like in GitHub Issues or Stack Overflow.
  3. API keys are usually bearer tokens without requiring any other identifying information. APIs cannot leverage things like one-time use tokens or 2-factor authentication.

If a key is exposed due to user error, one may think you as the API provider has any blame. However, security is all about reducing surface area and risk. Treat your customer data as if it’s your own and help them by adding guards that prevent accidental key exposure.

How to prevent accidental key exposure

The easiest way to prevent key exposure is by leveraging two tokens rather than one. A refresh token is stored as an environment variable and can only be used to generate short lived access tokens. Unlike the refresh token, these short lived tokens can access the resources, but are time limited such as in hours or days.

The customer will store the refresh token with other API keys. Then your SDK will generate access tokens on SDK init or when the last access token expires. If a CURL command gets pasted into a GitHub issue, then a hacker would need to use it within hours reducing the attack vector (unless it was the actual refresh token which is low probability)

Exposure to DDoS attacks

APIs open up entirely new business models where customers can access your API platform programmatically. However, this can make DDoS protection tricky. Most DDoS protection is designed to absorb and reject a large number of requests from bad actors during DDoS attacks but still need to let the good ones through. This requires fingerprinting the HTTP requests to check against what looks like bot traffic. This is much harder for API products as all traffic looks like bot traffic and is not coming from a browser where things like cookies are present.

Stopping DDoS attacks

The magical part about APIs is almost every access requires an API Key. If a request doesn’t have an API key, you can automatically reject it which is lightweight on your servers (Ensure authentication is short circuited very early before later middleware like request JSON parsing). So then how do you handle authenticated requests? The easiest is to leverage rate limit counters for each API key such as to handle X requests per minute and reject those above the threshold with a 429 HTTP response. There are a variety of algorithms to do this such as leaky bucket and fixed window counters.

Incorrect server security

APIs are no different than web servers when it comes to good server hygiene. Data can be leaked due to misconfigured SSL certificate or allowing non-HTTPS traffic. For modern applications, there is very little reason to accept non-HTTPS requests, but a customer could mistakenly issue a non HTTP request from their application or CURL exposing the API key. APIs do not have the protection of a browser so things like HSTS or redirect to HTTPS offer no protection.

How to ensure proper SSL

Test your SSL implementation over at Qualys SSL Test or similar tool. You should also block all non-HTTP requests which can be done within your load balancer. You should also remove any HTTP headers scrub any error messages that leak implementation details. If your API is used only by your own apps or can only be accessed server-side, then review Authoritative guide to Cross-Origin Resource Sharing for REST APIs

Incorrect caching headers

APIs provide access to dynamic data that’s scoped to each API key. Any caching implementation should have the ability to scope to an API key to prevent cross-pollution. Even if you don’t cache anything in your infrastructure, you could expose your customers to security holes. If a customer with a proxy server was using multiple API keys such as one for development and one for production, then they could see cross-pollinated data.

#api management #api security #api best practices #api providers #security analytics #api management policies #api access tokens #api access #api security risks #api access keys