springcloud 学习-eureka搭建

组件名：Netflix Eureka 

作用：支撑微服务的自注册、自发现，提供负载均衡能力

开发环境使用IDEA，jdk1.8

一、搭建eureka服务

1.新建maven项目，配置pom.xml文件

<parent>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-parent</artifactId>
    <version>Camden.SR7</version>
</parent>
<dependencies>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-eureka-server</artifactId>
    </dependency>
</dependencies>

2.新建启动类

@SpringBootApplication
@EnableEurekaServer
public class Application {
    public static void main(String[] args){
        SpringApplication.run(Application.class,args);
    }
}

3.新建配置文件application.yml

server:
  port: 1000
eureka:
  instance:
    hostname:  localhost
  client:
    register-with-eureka: false
    fetch-registry: false
spring:
  application:
    name: eureka-server

4.启动（启动类）

5.访问 eureka：http://localhost:1000/

erueka服务器启动成功，目前还未有服务注册

二、搭建服务提供方

1.新建maven项目，配置pom.xml文件

<parent>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-parent</artifactId>
    <version>Camden.SR7</version>
</parent>
<dependencies>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-eureka-server</artifactId>
    </dependency>
</dependencies>

2.创建Application启动类，提供/hello服务

@Configuration
@ComponentScan
@EnableEurekaClient
@EnableAutoConfiguration
@RestController
public class Application {
    @RequestMapping(value = "hello",method = RequestMethod.GET)
    public String hello(){
        return "你好,世界";
    }
    public static void main(String[] args){
        new SpringApplicationBuilder(Application.class).web(true)
                .run(args);
    }
}

3、新建application.yml配置文件

eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:1000/eureka/
spring:
  application:
    name: feign-client-test-001
server:
  port: 2000

查看路径id展示，需要添加配置

eureka:
  client:
    serviceUrl:
      defaultZone: http://admin:admin123@localhost:1000/eureka
  instance:
    prefer-ip-address: true

4、运行，查看之前Erueka服务端的页面，FEIGN-CLIENT-TEST-001在注册中心变为了大写这个注意下

5、访问：http://127.0.0.1:2000/hello

三、搭建服务消费方

使用@FeignClient注解

Feign is a declarative web service client. It makes writing web service clients easier.

如上是Spring Cloud文档中对于Feign的定义，结合之前的两篇博文，在这里我们就可以吧Feign简单的理解为用户（前端）可以直接接触到的REST接口提供者。在Feign中，我们可以方便的访问和使用意已经在Erueka服务器中注册过的服务了。

1、建立maven工程，配置pom.xml文件

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>1.5.2.RELEASE</version>
    <relativePath/> <!-- lookup parent from repository -->
</parent>

<properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
    <java.version>1.8</java.version>
</properties>

<dependencies>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-feign</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-eureka</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>Camden.SR6</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、建立包及启动类FeignApplication

/**
 * Created by gaofeng on 2017/7/14.
 */
@Configuration
@ComponentScan
@EnableAutoConfiguration
@EnableEurekaClient
@EnableFeignClients
@SpringBootApplication
public class FeignApplication {
    public static void main(String[] args) {
        SpringApplication.run(FeignApplication.class, args);
    }
}

3、建立接口类，用来调用上文中FEIGN-CLIENT-TEST-001服务的方法hello()，FEIGN-CLIENT-TEST-001是全大写的

@FeignClient("FEIGN-CLIENT-TEST-001")
public interface IHello {
    @RequestMapping(value = "/hello",method = RequestMethod.GET)
    String hello();
}

其中@FeignClient中指定需要调用的微服务的名称（全大写），@RequestMapping中指定访问微服务响应接口的路径，如之前微服务的hello方法是通过"/hello"路径访问，那么这里需要配置一致

4、新建Controller类，为前端提供REST接口

@RestController
public class HelloController {
    @Autowired
    private IHello iHello;
    @RequestMapping(value = "gethello",method = RequestMethod.GET)
    public String getHello() {
        return iHello.hello();
    }
}

5、配置Feign的配置文件，指定Eureka服务器注册地址和访问端口application.yml

server:
  port: 8081
eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:1000/eureka/
spring:
  application:
    name: feign-client-test-002

6、运行，查看之前Erueka服务端的页面

7、访问：http://127.0.0.1:8081/gethello

这里访问的就是feign-client-test-001的hello服务。