SpringCloud-Eureka-Provider&Consumer

Posted 2021-03-25 xj-record

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）