Actual combat of microservices | discovery and invocation of original ecosystem implementation services

Catalog

One 、 Service providers

  Two 、 Serving consumers

summary

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Related to recommend

Last one Eureka Registration center and cluster construction

Preface

 

In the last chapter , We introduced Eureka Establishment of registration center and cluster , This section will introduce the discovery and invocation of services . Be careful , At this time, we only have a registration center , No other components have been introduced , So we need to use SpringCloud The original way of service discovery and invocation , Take you step by step into the world of micro Services .

In the last article, we have created a registration center , This time we need to create a service provider （provider） And a service consumer （consumer） Two projects .

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One 、 Service providers

• newly build Maven project provider
• Introduce project dependencies

    <parent>
        <groupId>com.cxy965</groupId>
        <artifactId>parent</artifactId>
        <version>1.0-SNAPSHOT</version>
        <relativePath>../parent/pom.xml</relativePath>
    </parent>
    
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
    </dependencies>

• New configuration file application.yml

server:
  port: 8002
spring:
  application:
    name: provider

eureka:
  client:
    service-url:
      defaultZone: http://localhost:8001/eureka/
    fetch-registry: true

• Create startup classes and service interfaces , For simplicity , Temporarily put the service interface in the startup class , In actual projects , It's better to put it in controller in .

/**
 * @Author: official account ： The programmer 965
 * @create 2022-06-06
 **/
@EnableEurekaClient
@SpringBootApplication
@RestController
public class ProviderApplication {

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

    @GetMapping("/hello")
    public String hello(String name) {
       return "Hello "+name;
    }
}

•   Start to verify , Can return to .

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  Two 、 Serving consumers

• Reference resources provider Project creation consumer project
• Modify the port and application name in the configuration file to 8003、consumer
• Create startup class and service consumption code

/**
 * @Author: official account ： The programmer 965
 * @create 2022-06-06
 **/
@EnableEurekaClient
@SpringBootApplication
@RestController
public class ConsumerApplication {
    public static void main(String[] args) {
        SpringApplication.run(ConsumerApplication.class, args);
    }

    @Bean
    RestTemplate restTemplate() {
        return new RestTemplate();
    }

    @Autowired
    DiscoveryClient discoveryClient;
    @Autowired
    RestTemplate restTemplate;

    @GetMapping("/hello")
    public String hello(String name) {
        List<ServiceInstance> list = discoveryClient.getInstances("provider");
        ServiceInstance instance = list.get(0);
        String host = instance.getHost();
        int port = instance.getPort();
        String returnInfo = restTemplate.getForObject("http://" + host + ":" + port + "/hello?name={1}", String.class, name);
        return returnInfo;
    }
}

• Start to verify

You can see , We call 8003 Consumer services , The consumer service calls again 8002 Service provider's interface , And returned the result correctly .

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summary

Let's analyze the consumer code , Let's create a RestTemplate Bean example , Then pour in , Inject at the same time discoveryClient object .

In the interface , adopt discoveryClient.getInstances("provider") Method to get all the provider Service information ServiceInstance aggregate ,ServiceInstance It's actually an interface , The real implementation class is EurekaServiceInstance, By looking at EurekaServiceInstance Source code , We found that It contains a wealth of detailed information about the services in the registry （ Such as host address 、 Port number 、 example id, apply name 、 Application group name, etc ）.

Let's get the first service provider's ip And port （ In the case of cluster deployment , There may be multiple instances ）, And then by calling restTemplate.getForObject() Method to call the interface and get the return information .

In this way, the discovery and invocation of services are realized in the original way .

  Get the first instance and call the interface , Obviously, the goal of deploying multiple service instances is not achieved , The next article will Take you to implement a custom load balancer , Let's hope together ！