spring cloud(一) 服务注册与发现使用

2018-08-31 本文已影响135人 Learn_Java

使用场景

系统中有多个服务,服务之间使用轻量级通信协议例如http restful接口.但是服务之间的调用存在硬编码,无法动态伸缩.这时候就可以使用服务注册与发现组件

准备工作

框架以及版本号

框架	版本号
Spring Boot	1.4.0.RELEASE
Spring Cloud	Brixton.SR5

实例准备

实例	端口	功能
eureka-server	8761	注册发现服务器(单节点)
user-server	9090、9091	用户管理服务器(多节点,演示均衡负载)
eureka-client	8090	服务消费者,调用用户管理接口(演示用本身不提供服务)

实例调用关系图

服务之间的关系图.png

如何使用

使用Eureka组件

spring boot 的版本号

 <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.2.RELEASE</version>
 </parent>

spring cloud 的版本号

 <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Brixton.SR5</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

搭建注册中心eureka-server

<dependency>
    <groupId>org.springframework.cloud</groupId>
     <artifactId>spring-cloud-starter-eureka-server</artifactId>
</dependency>

eureka:
  client:
    # 服务器自身是否注册到eureka
    register-with-eureka: false
    # 是否同步节点
    fetch-registry: false
    # eureka页面url
    service-url:
      defaultZone: http://${eureka.instance.ip-address}:${server.port}/eureka/
  instance:
    ip-address: localhost
    hostname: discovery-server

server:
  port: 8761

spring:
  application:
    name: discovery-server

启动类Application

@SpringBootApplication
@EnableEurekaServer
public class ExampleSpringCloudEurekaServerApplication {

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

}

启动应用打开页面 http://localhost:8761
注册中心页面.png

从页面中看出Instances currently registered with Eureka当前还没有节点来注册中心注册

搭建用户管理服务器(user-server)

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

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
        </dependency>
</dependencies>

eureka:
  client:
    service-url:
      defaultZone: http://localhost:8761/eureka/
  instance:
    prefer-ip-address: true
    hostname: user-server

server:
  port: 8090

spring:
  application:
    name: user-server

暴露的接口

方便演示简单定义一个返回值.不用访问数据库

@RestController
@RequestMapping(value = "/user")
@Slf4j
public class UserController {

    @GetMapping
    private String getUser() {
        log.info("getUser ...");
        return "userId: 1";
    }
}

启动类

@SpringBootApplication
@EnableDiscoveryClient
public class ExampleSpringUserServerApplication {

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

}

启动多个应用实例

如何启动多个实例,可以先mvn package 打包成jar.然后使用命令
java -jar user-server.jar --server.port=9090
java -jar user-server.jar --server.port=9091

启动多个节点

多个节点启动.png
查看注册中心

注册中心页面.png
user-server节点已经被注册到注册中心

搭建服务消费者(eureka-client)

<dependencies>

    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-feign</artifactId>
    </dependency>

    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-ribbon</artifactId>
    </dependency>

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

</dependencies>

eureka:
  client:
    service-url:
      defaultZone: http://localhost:8761/eureka/
  instance:
    prefer-ip-address: true
    hostname: eureka-client

server:
  port: 8090

spring:
  application:
    name: eureka-client

启动类Application

@SpringBootApplication
@EnableDiscoveryClient
@EnableFeignClients
public class ExampleSpringCloudEurekaClientApplication {

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

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

feignClient
name = "user-server" 这个配置很重要,ribbon会在注册中心找可用的host-name.而这个user-server就是用户管理服务的host-name

@FeignClient(name = "user-server")
public interface UserServerFeign {

    @RequestMapping(value = "/user", method = RequestMethod.GET)
    String getUser();
}

暴露的接口(方便测试使用)

@RestController
public class UserFeignController {

    @Autowired
    private UserServerFeign userServerFeign;

    @GetMapping("/feign/user")
    private String getUserByFeign() {
        return userServerFeign.getUser();
    }
}