Spring Cloud - Eureka Client

一.前言

在Spring Cloud 之Eureka Server中,我們介紹了Eureka Server的搭建,今天我們來搭建Eureka Client。然後完成下面的案例

二.服務生產者

2.1 創建項目

經過上面的一頓操作,我們已經成功創建項目,下面我們來看下項目結構

2.2 pom.xml文件

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>com.milo</groupId>
        <artifactId>milgenius-springcloud</artifactId>
        <version>1.0.0</version>
    </parent>
    <groupId>com.milo</groupId>
    <artifactId>springcloud-service-provider</artifactId>
    <version>1.0.0</version>
    <name>springcloud-service-provider</name>
    <description>服務提供者</description>

    <properties>
        <java.version>1.8</java.version>
    </properties>

    <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>


    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

2.3 添加註解@EnableDiscoveryClient

package com.milo.provider;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;


@SpringBootApplication
@EnableDiscoveryClient
public class ServiceProviderApplication {

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

}

2.4 配置文件

#服務命名
spring:
  application:
    name: service-provider

#服務註冊中心地址
eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8761/eureka/

server:
  port: 8762

2.5 模擬一個服務接口

/**
 * @author: Milogenius
 * @create: 2019-06-28 12:14
 * @description:
 **/
@RestController
@Slf4j
public class ProviderController {

    @Autowired
    private DiscoveryClient client;

    /**
     * 模擬一個服務接口
     * @return
     */
    @RequestMapping(value = "/hello",method = RequestMethod.GET)
    public String index(){
        List<ServiceInstance> instances = client.getInstances("service-provider");
        ServiceInstance instance = instances.get(0);
        log.info("hello, host:" + instance.getHost()+",service_id:"+instance.getServiceId());
        return "hello world";
    }
}

三.服務消費者

3.1 創建項目

經過上面的一頓操作,我們已經成功創建項目,下面我們來看下項目結構

3.2 pom.xml文件

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>com.milo</groupId>
        <artifactId>milgenius-springcloud</artifactId>
        <version>1.0.0</version>
    </parent>
    <groupId>com.milo</groupId>
    <artifactId>springcloud-service-consumer</artifactId>
    <version>1.0.0</version>
    <name>springcloud-service-consumer</name>
    <description>服務消費者</description>

    <properties>
        <java.version>1.8</java.version>
        <spring-cloud.version>Greenwich.SR1</spring-cloud.version>
    </properties>

    <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>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

3.3 添加註解@EnableDiscoveryClient

package com.milo.consumer;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;

@SpringBootApplication
@EnableDiscoveryClient
public class ServiceConsumerApplication {

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

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

3.4 配置文件

eureka:
  client:
  serviceUrl:
    defaultZone: http://localhost:8761/eureka/

server:
  port: 8764

spring:
  application:
    name: service-consumer

3.5 模擬一個業務

/**
 * @author: Milogenius
 * @create: 2019-06-28 13:45
 * @description:
 **/
@RestController
public class ConsumerController {

    @Autowired
    private IConsumerService consumerService;
    @RequestMapping(value = "/hello",method = RequestMethod.GET)
    public String index(@RequestParam String name){
        return  consumerService.hello(name);
    }
}

/**
 * @author: Milogenius
 * @create: 2019-06-28 13:48
 * @description:
 **/
public interface IConsumerService {

    String hello(String name);
}

/**
 * @author: Milogenius
 * @create: 2019-06-28 13:49
 * @description:
 **/
@Service
public class ConsumerServiceImpl implements IConsumerService {

    @Autowired
    RestTemplate restTemplate;
    @Override
    public String hello(String name) {
        return restTemplate.getForObject("http://SERVICE-PROVIDER:8762/hello?name="+name,String.class);
    }
}

四.服務間調用

首次我們啓動springcloud-eureka-serverEureka Server

瀏覽器訪問http://localhost:8761/

接着我們啓動springcloud-service-provider 服務提供者Eureka Client

瀏覽器訪問http://localhost:8761/

最後,我們啓動springcloud-service-consumer服務消費者Eureka Client

瀏覽器訪問http://localhost:8761/

至此,我們完成了項目的搭建和服務的註冊,接下來我們測試服務間的調用;

在我們大家服務消費者項目時候,我們模擬了一個業務,在ConsumerServiceImpl類的hello方法中我們模擬調用了另外一個服務;

瀏覽器訪問http://localhost:8764/hello?name=milogenius

我們發現,頁面成功響應helloworld;現在我們去服務生產者看一下後臺日誌;

五.結論

經過上面的學習,我們完成了Spring Cloud之Eureka的服務的註冊和發現,並完成服務之間的調用;