SpringCloud uses Ribbon to achieve load balancing
Maven coordinates of dependent class libraries:
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
<version>2.2.3.RELEASE</version>
</dependency>
This class library is a component provided by Spring Cloud Alibaba for implementing service registration and discovery. By calling the interface provided by this class library, services can be registered with the Nacos registry and a list of available service instances can be obtained from the registry to achieve load balancing. This class library mainly includes the following core classes:
1. '@ enableDiscoveryClient': A Spring annotation used to enable service registration and discovery functionality.
2. 'NacosDiscoveryProperties': Used to configure the address, namespace, cluster, and other information of the Nacos registry.
3. 'NacosServiceRegistry': Used to register service instances with the Nacos registry.
4. 'NacosServiceDiscovery': Used to obtain a list of available service instances from the Nacos registry.
By combining the above class libraries and classes, Nacos based service registration and discovery can be achieved, and load balancing can be achieved in conjunction with the Ribbon.
The following is a complete example of using the Ribbon to achieve load balancing, including service registration and discovery, load balancing configuration, and invocation examples:
Firstly, add the annotation '@ enableDiscoveryClient' on the startup class of Spring Boot to enable service registration and discovery functions.
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
@SpringBootApplication
@EnableDiscoveryClient
public class Application {
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
}
2. Configure the address and other information of the Nacos registration center in the 'application. properties' file.
properties
nacos.discovery.server-addr=127.0.0.1:8848
3. Create a simple example of service providers and service consumers. The code for the service provider is as follows:
@RestController
public class HelloController {
@GetMapping("/hello")
public String hello() {
return "Hello from service provider!";
}
}
4. Create code for a service consumer that utilizes the ribbon for service invocation and load balancing. The code is as follows:
@RestController
public class HelloController {
@Autowired
private LoadBalancerClient loadBalancerClient;
@GetMapping("/hello")
public String hello() {
ServiceInstance serviceInstance = loadBalancerClient.choose("service-provider");
String url = "http://" + serviceInstance.getHost() + ":" + serviceInstance.getPort() + "/hello";
RestTemplate restTemplate = new RestTemplate();
return restTemplate.getForObject(url, String.class);
}
}
5. Start the service provider and service consumer, and access the application through the service consumer's URL. It can be seen that the service consumer will select an available service provider to call based on the load balancing algorithm.
Finally, to summarize, the steps for using Ribbon to achieve load balancing in Spring Cloud are as follows:
1. Add Maven coordinates for dependent class libraries.
2. Add the @ EnableDiscoveryClient annotation on the startup class to enable service registration and discovery functionality.
3. Configure the address and other information of the Nacos registration center.
4. Create code for service providers and service consumers.
5. Use the ribbon in the service consumer code to make service calls and achieve load balancing.
