Step by Step Guide to Building a Harvest API Integration in Java

Introduction

Hey there, fellow code wrangler! Ready to dive into the world of Harvest API integration? You're in for a treat. Harvest's API is a powerhouse for time tracking and project management, and we're about to harness that power in Java. Buckle up!

Prerequisites

Before we jump in, make sure you've got:

• A Java development environment (I know you've got this covered)
• A Harvest account with API credentials (if not, hop over to Harvest and set one up)
• Your favorite HTTP client library (we'll be using OkHttp in this guide)

Setting Up the Project

Let's get the boring stuff out of the way:

1. Fire up your IDE and create a new Java project.
2. Add your HTTP client dependency. If you're using Maven, toss this into your pom.xml:

<dependency>
    <groupId>com.squareup.okhttp3</groupId>
    <artifactId>okhttp</artifactId>
    <version>4.10.0</version>
</dependency>

Authentication

Harvest uses personal access tokens for API authentication. It's simple and secure. Here's how to use it:

OkHttpClient client = new OkHttpClient();
Request request = new Request.Builder()
    .url("https://api.harvestapp.com/v2/users/me")
    .addHeader("Harvest-Account-ID", "YOUR_ACCOUNT_ID")
    .addHeader("Authorization", "Bearer YOUR_ACCESS_TOKEN")
    .build();

Making API Requests

Now for the fun part - let's make some requests!

GET Request

Want to fetch your time entries? Here's how:

Request request = new Request.Builder()
    .url("https://api.harvestapp.com/v2/time_entries")
    .addHeader("Harvest-Account-ID", "YOUR_ACCOUNT_ID")
    .addHeader("Authorization", "Bearer YOUR_ACCESS_TOKEN")
    .build();

Response response = client.newCall(request).execute();
System.out.println(response.body().string());

POST Request

Creating a new project? Easy peasy:

String json = "{\"client_id\":\"12345\",\"name\":\"My Awesome Project\"}";
RequestBody body = RequestBody.create(json, MediaType.parse("application/json"));

Request request = new Request.Builder()
    .url("https://api.harvestapp.com/v2/projects")
    .addHeader("Harvest-Account-ID", "YOUR_ACCOUNT_ID")
    .addHeader("Authorization", "Bearer YOUR_ACCESS_TOKEN")
    .post(body)
    .build();

Response response = client.newCall(request).execute();
System.out.println(response.body().string());

Error Handling and Rate Limiting

Don't forget to handle those pesky errors and respect rate limits. Harvest's pretty generous, but let's play nice:

if (!response.isSuccessful()) {
    throw new IOException("Unexpected code " + response);
}

// Check rate limit headers
String rateLimit = response.header("X-Rate-Limit-Remaining");
if (Integer.parseInt(rateLimit) < 10) {
    // Maybe slow down a bit?
}

Data Parsing and Manipulation

JSON is your friend here. Use your favorite JSON library (I'm partial to Gson) to parse those responses:

Gson gson = new Gson();
TimeEntry[] timeEntries = gson.fromJson(response.body().string(), TimeEntry[].class);

Implementing Key Harvest API Features

Now that you've got the basics down, sky's the limit! You can implement time tracking, project management, invoicing - whatever your heart desires. The Harvest API docs are your playground.

Best Practices

A few tips to keep in mind:

• Cache data when possible to reduce API calls
• Use HTTPS for all requests (but you knew that already)
• Keep your access token safe and sound

Testing the Integration

You're a pro, so I know you're writing tests. Here's a quick example using JUnit:

@Test
public void testGetTimeEntries() {
    // Your test code here
    assertNotNull(timeEntries);
    assertTrue(timeEntries.length > 0);
}

Conclusion

And there you have it! You're now armed and dangerous with Harvest API integration skills. Remember, this is just scratching the surface - there's so much more you can do. Happy coding, and may your projects always be on time and under budget!

For more details, check out the Harvest API Documentation. Now go forth and conquer those time sheets!