Spring MVC - Comparison of Cryptocurrencies using REST API

Spring MVC - Comparison of Cryptocurrencies using REST API

Spring MVC allows you to create web applications that can consume RESTful services. In this example, let's design a simple Spring MVC application to compare cryptocurrency prices using a RESTful API. We'll be using the CoinGecko API for this purpose as it's free and doesn't require an API key.

1. Maven Dependencies

Add the required dependencies in pom.xml.

<dependencies> <!-- Spring Web MVC --> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-webmvc</artifactId> <version>5.3.10</version> </dependency> <!-- Spring Web for RESTful service --> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-web</artifactId> <version>5.3.10</version> </dependency> <!-- JSON Processing --> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-databind</artifactId> <version>2.12.3</version> </dependency> </dependencies>

2. Model

Create a model for the cryptocurrency data.

public class Cryptocurrency { private String id; private String name; private String current_price; // Getters and setters }

3. Service

Create a service to fetch and process cryptocurrency data.

@Service public class CryptocurrencyService { private final String API_URL = "https://api.coingecko.com/api/v3/coins/markets"; @Autowired private RestTemplate restTemplate; public Cryptocurrency getPrice(String cryptoName) { UriComponentsBuilder uriBuilder = UriComponentsBuilder.fromHttpUrl(API_URL) .queryParam("vs_currency", "usd") .queryParam("ids", cryptoName) .queryParam("order_by", "market_cap_desc") .queryParam("limit", "10") .queryParam("sparkline", "false") .queryParam("price_change_percentage", "24h"); ResponseEntity<Cryptocurrency[]> response = restTemplate.getForEntity( uriBuilder.toUriString(), Cryptocurrency[].class ); return response.getBody()[0]; } }

4. Controller

Design a controller to handle user requests.

@Controller @RequestMapping("/crypto") public class CryptocurrencyController { @Autowired private CryptocurrencyService cryptocurrencyService; @GetMapping("/compare") public String compare(@RequestParam("name") String cryptoName, Model model) { Cryptocurrency crypto = cryptocurrencyService.getPrice(cryptoName); model.addAttribute("crypto", crypto); return "cryptoDetails"; } }

5. View

Create a JSP to display the cryptocurrency data (cryptoDetails.jsp).

<html> <body> Cryptocurrency: ${crypto.name} <br/> Current Price (in USD): ${crypto.current_price} </body> </html>

6. Spring Configuration

Configure Spring MVC and RestTemplate bean.

@Configuration @EnableWebMvc @ComponentScan(basePackages = "com.example.demo") public class AppConfig implements WebMvcConfigurer { @Bean public RestTemplate restTemplate() { return new RestTemplate(); } @Override public void configureViewResolvers(ViewResolverRegistry registry) { InternalResourceViewResolver resolver = new InternalResourceViewResolver(); resolver.setPrefix("/WEB-INF/views/"); resolver.setSuffix(".jsp"); registry.viewResolver(resolver); } }

With this setup, users can visit /crypto/compare?name=bitcoin to view the current price of Bitcoin in USD. Similarly, you can expand this functionality to include more cryptocurrencies, different currencies, or even different metrics.

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