Today, we will take a deep dive into the world of cryptocurrency data. We'll fetch live data from the Binance API using Java's Spring Boot framework.

API Overview

Binance's API is an interface that allows us to interact with the Binance platform programmatically. It provides live trading functionality, market data, account management, and more. More details on official documentation.

Generating an API Key

We need an API Key. You can generate this from your Binance account. Head to the API Management page in your account settings, create a new API, and label it. You'll receive your API Key and Secret Key.

Creating a Spring Boot Application

Create a new Spring Boot application. Full example in Spring Boot reference guide.

Next, add the following dependencies to your Maven pom.xml:

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
        <groupId>com.squareup.okhttp3</groupId>
        <artifactId>okhttp</artifactId>
        <version>4.9.0</version>
    </dependency>
</dependencies>

We're using the OkHttp library to handle HTTP requests, and Spring Boot's web starter for our RESTful services.

Implementing the BinanceService

Create a BinanceService to interact with the Binance API.

import okhttp3.*;
import org.springframework.stereotype.Service;

import java.io.IOException;

@Service
public class BinanceService {
    private final OkHttpClient client;
    private static final String API_URL = "https://api.binance.com";
    private static final String API_KEY = "your-api-key";

    public BinanceService() {
        this.client = new OkHttpClient();
    }

    public String getTrades(String symbol) throws IOException {
        HttpUrl.Builder urlBuilder = HttpUrl.parse(API_URL + "/api/v3/trades").newBuilder();
        urlBuilder.addQueryParameter("symbol", symbol);

        Request request = new Request.Builder()
                .url(urlBuilder.build())
                .addHeader("X-MBX-APIKEY", API_KEY)
                .build();

        try (Response response = client.newCall(request).execute()) {
            return response.body().string();
        }
    }
}

The getTrades method fetches the latest trades for a given cryptocurrency symbol from Binance.

Creating a REST Controller

We'll now create a REST controller to expose our BinanceService as an HTTP endpoint:

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class BinanceController {

    private final BinanceService binanceService;

    public BinanceController(BinanceService binanceService) {
        this.binanceService = binanceService;
    }

    @GetMapping("/trades/{symbol}")
    public String getTrades(@PathVariable String symbol) throws IOException {
        return binanceService.getTrades(symbol);
    }
}

You can navigate to http://localhost:8080/trades/BTCUSDT to fetch the latest trades for the BTCUSDT symbol. It is just for your local testing. If you need to use it not from localhost you have to expose this service

Our example only fetches trade data, the Binance API offers much more. You can explore account information, live trading, and more in your applications.