Using Spring RestTemplate in JAX-RS project

Question

My project consist of 5 modules. And only one of them uses JAX-RS, others use Spring. My current task is develop service, that will be send HTTP requests to some API. I wanna use Spring RestTemplate for this task, but problem is project with JAX-RS haven't RestTemplate class and other needfull dependencies. I wanna use:

<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-web</artifactId>
    <version>4.2.5.RELEASE</version>
</dependency>

in the JAX-RS module, to avoid code duplicating for RestTemplate and for some JAX-RS client. Is it good idea? Will be RestTemplate work properly without spring-core dependency?

Answer 1

Using RestTemplate

To use RestTemplate you need just the spring-web dependency:

<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-web</artifactId>
    <version>4.3.3.RELEASE</version>
</dependency>

The spring-web dependency has spring-core as a transitive dependency.

To use RestTemplate it's as simple as:

public class ExampleWithRestTemplate {

    public static void main(String[] args) {

        RestTemplate restTemplate = new RestTemplate();
        ResponseEntity<String> response = 
            restTemplate.getForEntity("http://date.jsontest.com", String.class);
        System.out.println(response.getBody());
    }
}

Considering JAX-RS Client API as an alternative

Instead of RestTemplate you also could consider JAX-RS 2.0 Client API to consume REST web services. Jersey is the JAX-RS reference implementation and offers a great API.

To use Jersey Client API, the following dependency is required:

<dependency>
    <groupId>org.glassfish.jersey.core</groupId>
    <artifactId>jersey-client</artifactId>
    <version>2.23.2</version>
</dependency>

For more details, have a look at the documentation.

You also could consider the Jersey Client Proxy API. The basic idea of this approach is to attach the standard JAX-RS annotations to an interface, and then implement that interface by a resource class on the server side while reusing the same interface on the client side by dynamically generating an implementation of that using java.lang.reflect.Proxy calling the right low-level client API methods.

To use the Jersey Client Proxy API, the following dependency is required:

<dependency>
    <groupId>org.glassfish.jersey.ext</groupId>
    <artifactId>jersey-proxy-client</artifactId>
    <version>2.23.2</version>
</dependency>