# OpenFeign

Paul Tomoiu

●

Examples,

Spring,

Cloud,

OpenFeign,

RestTemplate,

API calls

●

Published 2023-07-01

This tutorial explains how to use Spring Cloud OpenFeign. This tutorial contains an example as well.

OpenFeign is a way we can call a service without using the well-known RestTemplate class.

For implementing this, first of all we need to create a simple Spring Boot application using spring initializr as in the image below:

What is important is to have the following dependency in pom.xml:

<dependency>
    <groupId>org.springframework.cloud</groupId>
	<artifactId>spring-cloud-starter-openfeign</artifactId>
</dependency>

Now we need to add @EnableFeignClients annotation to the main class of the application.

Now the main class will look like this:

OpenFeignApplication.java
package com.example.openfeign;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.openfeign.EnableFeignClients;

@SpringBootApplication
@EnableFeignClients
public class OpenFeignApplication {

	public static void main(String[] args) {
		SpringApplication.run(OpenFeignApplication.class, args);
	}
}

We need to add the @FeignClient to an interface. This interface defines the call to the external API. In my case the interface looks like:

MyInterface.java
package com.example.openfeign;

import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;

@FeignClient(name="myInterfaceName", url="https://www.boredapi.com/api")
public interface MyInterface {

    @GetMapping("/activity")
    String getMyServiceCall1();

}

myInterfaceName : is the name of the interface (could be any name) https://www.boredapi.com/api : the base URL for the external call /activity : will be added to the base URL for creating the final URL

Info

Instead adding url="https://www.boredapi.com/api" in the interface annotation we can add spring.cloud.openfeign.client.config.myInterfaceName.url=https://www.boredapi.com/api in application.properties configuration file. In the last approach we can configure better the OpenFeign client.

Now we can define the application controller:

MyController.java
package com.example.openfeign;

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

@RestController
public class MyController {

    final MyInterface myInterface;

    public MyController(MyInterface myInterface) {
        this.myInterface = myInterface;
    }

    @GetMapping("/call")
    public String status() {

        var var1 =  myInterface.getMyServiceCall1();
        return var1;
    }
}

That's all.

Now we start our Spring Boot application, and we put http://localhost:8080/call address in a browser.

In Firefox, we can see the following :

What we can see is what we receive from https://www.boredapi.com/api/activity GET call.

Enjoy OpenFeign ! It is easy !