Spring Boot is a popular framework for developing REST APIs. It provides a wide range of features that make it easier to build and test applications. One common use case when building a REST API is to call another REST API as part of the processing of an incoming request. This can be useful, for example, when integrating with a third-party service or aggregating data from multiple sources.
In this post, we’ll look at how to call another REST API from a Spring Boot server.
Step 1: Add the RestTemplate to Your Project
The first step is to add the RestTemplate to your project. The RestTemplate is a class provided by Spring that makes it easy to call REST APIs. To add it to your project, you’ll need to include the following dependency in your build file:
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
Step 2: Create a RestTemplate Bean
Next, you’ll need to create a bean for the RestTemplate in your Spring Boot configuration. This can be done in the following way:
@Bean
public RestTemplate restTemplate() {
return new RestTemplate();
}
Step 3: Call the REST API
With the RestTemplate in place, you’re ready to call another REST API. This can be done in the following way:
@Autowired
private RestTemplate restTemplate;
public void callRestApi() {
ResponseEntity<String> response = restTemplate.getForEntity("https://example.com/api", String.class);
System.out.println(response.getBody());
}
In this example, the getForEntity method is called on the RestTemplate to make a GET request to the specified URL. The response is returned as a ResponseEntity, which contains the response body, headers, and status code.
Step 4: Handle Exceptions
It’s important to handle exceptions when calling a REST API, as things can go wrong. For example, the API may be down or the request may be invalid. To handle exceptions, you can wrap the call to the REST API in a try-catch block and handle the exception appropriately:
public void callRestApi() {
try {
ResponseEntity<String> response = restTemplate.getForEntity("https://example.com/api", String.class);
System.out.println(response.getBody());
} catch (RestClientException e) {
System.out.println("An error occurred while calling the REST API: " + e.getMessage());
}
}
In this example, the RestClientException is caught, which is a common exception that can occur when calling a REST API with the RestTemplate.
Conclusion
In this post, we’ve looked at how to call another REST API from a Spring Boot server. We’ve seen how to add the RestTemplate to your project, create a bean for it, call the REST API, and handle exceptions. With these steps in place, you’ll be able to call another REST API as part of your Spring Boot applications.