Spring Cloud - Feign Client with Eureka

Let us say we want to find restaurants which are in the same city as that of the customer. We will use the following services −

• Customer Service − Has all the customer information. We had defined this in Eureka Client section earlier.

• Eureka Discovery Server − Has information about the above services. We had defined this in the Eureka Server section earlier.

• Restaurant Service − New service which we will define which has all the restaurant information.

We're using client service created in Spring Cloud - Creating Eureka Client chapter,and Eureka Server created in Spring Cloud - Creating Eureka Server.

Let us first add a basic controller to our Customer service −

RestaurantCustomerInstancesController.java

package com.tutorialspoint.eurekaclient;

import java.util.HashMap;

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

@RestController
class RestaurantCustomerInstancesController {
   static HashMap<Long, Customer> mockCustomerData = new HashMap<>();
   static{
      mockCustomerData.put(1L, new Customer(1, "Jane", "DC"));
      mockCustomerData.put(2L, new Customer(2, "John", "SFO"));
      mockCustomerData.put(3L, new Customer(3, "Kate", "NY"));
   }
   @RequestMapping("/customer/{id}")
   public Customer getCustomerInfo(@PathVariable("id") Long id) {
      return mockCustomerData.get(id);
   }
}

We will also define a Customer.java POJO for the above controller.

Customer.java

package com.tutorialspoint.eurekaclient;

public class Customer {
   private long id;
   private String name;
   private String city;
   public Customer() {}
   public Customer(long id, String name, String city) {
      super();
      this.id = id;
      this.name = name;
      this.city = city;
   }
   public long getId() {
      return id;
   }
   public void setId(long id) {
      this.id = id;
   }
   public String getName() {
      return name;
   }
   public void setName(String name) {
      this.name = name;
   }
   public String getCity() {
      return city;
   }
   public void setCity(String city) {
      this.city = city;
   }
}

Now let us move to define the Feign client which the Restaurant service will use to get the customer city.

CustomerService.java

package com.tutorialspoint.eurekaclient;

import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;

@FeignClient(name = "restaurant-service")
public interface CustomerService {
   @RequestMapping("/customer/{id}")
   public Customer getCustomerById(@PathVariable("id") Long id);
}

The Feign client contains the name of the service and the API call we plan to use in the Restaurant service.

Finally, let us define a controller in the Restaurant service which would use the above interface.

RestaurantController.java

package com.tutorialspoint.eurekaclient;

import java.util.HashMap;
import java.util.List;
import java.util.stream.Collectors;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
class RestaurantController {
   @Autowired
   CustomerService customerService;
   static HashMap<Long, Restaurant> mockRestaurantData = new HashMap();
   static{
      mockRestaurantData.put(1L, new Restaurant(1, "Pandas", "DC"));
      mockRestaurantData.put(2L, new Restaurant(2, "Indies", "SFO"));
      mockRestaurantData.put(3L, new Restaurant(3, "Little Italy", "DC"));
   }
   @RequestMapping("/restaurant/customer/{id}")
   public List<Restaurant> getRestaurantForCustomer(@PathVariable("id") Long id) {
      String customerCity = customerService.getCustomerById(id).getCity();
      return mockRestaurantData.entrySet().stream().filter(
         entry -> entry.getValue().getCity().equals(customerCity))
           .map(entry -> entry.getValue())
           .collect(Collectors.toList());
   }
}

The most important line here is the following −

customerService.getCustomerById(id)

which is where the magic of API calling by Feign client we defined earlier happens.

Let us also define the Restaurant POJO −

package com.tutorialspoint.eurekaclient;

public class Restaurant {
   private long id;
   private String name;
   private String city;
   public Restaurant(long id, String name, String city) {
      super();
      this.id = id;
      this.name = name;
      this.city = city;
   }
   public long getId() {
      return id;
   }
   public void setId(long id) {
      this.id = id;
   }
   public String getName() {
      return name;
   }
   public void setName(String name) {
      this.name = name;
   }
   public String getCity() {
      return city;
   }
   public void setCity(String city) {
      this.city = city;
   }
}

Once this is defined, let us create a simple JAR file with the following application.yml file −

spring:
   application:
      name: restaurant-service
server:
   port: 8080
eureka:
   client:
      serviceURL:
         defaultZone: http://localhost:8900/eureka