服务的注册与发现-Eureka

Eureka就是帮助我们维护所有服务的信息，以便服务之间的相互调用

1 Eureka的快速入门

1.1 创建EurekaServer

1.1.1 创建一个父工程，并且在父工程中指定SpringCloud的版本，并且将packaing修改为pom

<packaging>pom</packaging>
<parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.3.12.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
<dependencyManagement>
   <dependencies>
       <dependency>
          <groupId>org.springframework.cloud</groupId>
          <artifactId>spring-cloud-dependencies</artifactId>
          <version>Hoxton.SR12</version>
          <type>pom</type>
          <scope>import</scope>
        </dependency>
   </dependencies>
</dependencyManagement>

创建eureka的server，创建SpringBoot工程，并且导入依赖，在启动类中添加注解，编写yml文件
1.1.2 导入依赖

<dependencies>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
</dependencies>

1.1.3 启动类添加注解

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

1.1.4 编写yml

server:
  port: 8761 # 端口号
eureka:
  instance:
    hostname: localhost   # localhost
  client:
    # 当前的eureka服务是单机版的
    registerWithEureka: false
    fetchRegistry: false
    serviceUrl:
      defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka/

1.2 创建EurekaClient

创建Maven工程，修改为SpringBoot
1.2.1 导入依赖

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

1.2.2
在启动类上添加注解

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

1.2.3 编写配置文件

# 指定Eureka服务地址
eureka:
  client:
    service-url:
      defaultZone: http://localhost:8761/eureka
# 指定服务的名称
spring:
  application:
    name: CUSTOMER

1.3 测试Eureka

@Autowired
private EurekaClient eurekaClient;
@GetMapping("/customer")
public String customer(){
    //1. 通过eurekaClient获取到SEARCH服务的信息
    InstanceInfo info = eurekaClient.getNextServerFromEureka("SEARCH", false);
    //2. 获取到访问的地址
    String url = info.getHomePageUrl();
    System.out.println(url);
    //3. 通过restTemplate访问
    String result = restTemplate.getForObject(url + "/search", String.class);
    //4. 返回
    return result;
}

1.4 启动类中配置（各人配置不一样） RestTemplate

@SpringBootApplication
@EnableEurekaClient
public class UserApplication {
    public static void main(String[] args) {
        SpringApplication.run(UserApplication.class,args);
    }
    @Bean
    public RestTemplate restTemplate(){
        return new RestTemplate();
    }
}