SpringCloud Eureka Provider及Consumer的实现

Eureka-Provider 服务的提供者

新建一个服务提供者项目

1、导入pom文件

<properties>
    <java.version>1.8</java.version>
    <spring-cloud.version>Greenwich.SR3</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>

  <dependencyManagement>
    <dependencies>
      <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-dependencies</artifactId>
        <version>${spring-cloud.version}</version>
        <type>pom</type>
        <scope>import</scope>
      </dependency>
    </dependencies>
  </dependencyManagement>

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

2、在启动类上加注解

@SpringBootApplication
@EnableDiscoveryClient // 这个注解加不加都可以,因为Eureka
public class EurekaProviderApplication {
  public static void main(String[] args) {
    SpringApplication.run(EurekaProviderApplication.class, args);
  }
}

上边那个@EnableDiscoverClient 注解加不加都行的原因会在后边表名

3、在Eureka-Provider项目中添加一个简单的接口

@RestController
public class EurekaProviderController {
  @GetMapping("/provider")
  public String provider(@RequestParam String aaa){
    return "eureka-provider-return" + aaa;
  }
}

4、以上配置完成之后启动Eureka-Provider

启动后会在控制台输出

DiscoveryClient_EUREKA-PROVIDER/192.168.1.4:eureka-provider:8000: registering service...

​同时看localhost:8761 页面的Instance currently registered 会多出一条信息

Application AMIs Availability Zones Status

EUREKA-PROVIDER n/a (1) (1) UP (1) - 192.168.1.4:eureka-provider:8000

Eureka-Consumer 服务的调用者

调用者的配置和上边提供者类似,applicatioin.yml配置修改server.port=8100

1、启动类修改

@SpringBootApplication  // 另一个发现服务的注解可以不用谢(SpringCloud版本要在Edgware之后)
public class EurekaConsumerApplication {
  @Bean
  @LoadBalanced
  RestTemplate restTemplate(){
    return new RestTemplate();
  }
  public static void main(String[] args) {
    SpringApplication.run(EurekaConsumerApplication.class, args);
  }
}

2、编写一个调用接口的类

@RestController
public class EurekaConsumerController {
  @Autowired
  private RestTemplate restTemplate;
  @GetMapping("/consumer")
  @GetMapping("/consumer")
  public String consumer(@RequestParam String aaa){
    return restTemplate.getForObject("http://EUREKA-PROVIDER/provider?aaa=" + aaa,String.class );
  }
}

3、启动服务调用者

​ 启动后,调用调用者的触发地址localhost:8100/consumer?aaa=consumerSemdParamter

​ 浏览器显示内容:

eureka-provider-returnconsumerSemdParamter

上边遗留的一个问题,eureka-client不加@EnableDiscoveryClient以将自己注册到注册中心

先看EurekaClientAutoConfiguration类中

@Configuration
@EnableConfigurationProperties
@ConditionalOnClass(EurekaClientConfig.class)
@Import(DiscoveryClientOptionalArgsConfiguration.class)
@ConditionalOnBean(EurekaDiscoveryClientConfiguration.Marker.class)
@ConditionalOnProperty(value = "eureka.client.enabled", matchIfMissing = true)
@ConditionalOnDiscoveryEnabled
@AutoConfigureBefore({ NoopDiscoveryClientAutoConfiguration.class,
   CommonsClientAutoConfiguration.class, ServiceRegistryAutoConfiguration.class })
@AutoConfigureAfter(name = {
   "org.springframework.cloud.autoconfigure.RefreshAutoConfiguration",
   "org.springframework.cloud.netflix.eureka.EurekaDiscoveryClientConfiguration",
   "org.springframework.cloud.client.serviceregistry.AutoServiceRegistrationAutoConfiguration" })
public class EurekaClientAutoConfiguration {
}

可以看到该类加载的条件是需要有EurekaDiscoveryClientConfiguration.Maker.class的Bean存在,并且eureka.client.enabled为true,因为该值默认为true,所以不需要关注,因此重要的就是EurekaDiscoveryClientConfiguration.Maker.class这个,而这个类在Dalston之前的旧版本是不会自动加载的,而在Edgware之后,该类就配置到spring.factories文件中了,改文件中所配置的bean在springboot启动的时候就会被加载(所以不需要手动配上注册服务的注解了,springboot会自动配置)

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