Eureka注册中心的基本使用

骑猪看日落 2022-12-22 16:18 318阅读 0赞

# 导包 #

新建一个工程或者模块 eureka-server 作为eureka服务器

注意:SpringBoot和SpringCloud的依赖就不提及了,相信你自己都导入了,注意版本对应关系  
我这个版本是: `Greenwich.SR1`

## 服务端导包 ##

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

## 注册到Eureka的其他工程导入 ##

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

# eureka服务器端 #

导包完成后,在启动类上加入 `@EnableEurekaServer` 注解

import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer;
    
    @SpringBootApplication
    @EnableEurekaServer //开启 Eureka服务端
    public class EurekaServiceApplication { 
        public static void main(String[] args) { 
            SpringApplication.run(EurekaServiceApplication.class,args);
        }
    }

编写配置文件,在 `application.yml` 编写如下:

server:
      port: 10086
    spring:
      application:
        name: eureka-server # 应用名称(当前模块或者项目名称)，会在Eureka中作为服务的id标识（serviceId）
    eureka:
      client:
        service-url: # EurekaServer的地址，现在是自己的地址，如果是集群，需要写其它Server的地址。
          defaultZone: http://127.0.0.1:10086/eureka
        register-with-eureka: false # 不注册自己
        fetch-registry: false #不拉取服务

## 启动 ##

启动Springboot启动类  
访问Eureka服务端访问地址: http://127.0.0.1:10086  
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# 服务注册 #

启动类添加 `@SpringCloudApplication` 就可以它继承了 `@SpringBootApplication` , `@EnableDiscoveryClient`  
具体看代码  
如果启动不起来,就用 `@EnableDiscoveryClient`

import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    import org.springframework.cloud.client.SpringCloudApplication;
    import org.springframework.cloud.client.circuitbreaker.EnableCircuitBreaker;
    import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
    import org.springframework.cloud.client.loadbalancer.LoadBalanced;
    import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
    import org.springframework.context.annotation.Bean;
    import org.springframework.http.converter.StringHttpMessageConverter;
    import java.nio.charset.StandardCharsets;
    
    @SpringBootApplication
    //@EnableEurekaClient 表示当前项目是eureka注册中心的客户端
    @EnableDiscoveryClient  //表示是注册中心的客户端 不限于是哪个注册中心可以是eureka也可以是zookeeper 可以省略
    //@EnableCircuitBreaker
    //@SpringCloudApplication
    public class EurekaClientApplication { 
        public static void main(String[] args) { 
            SpringApplication.run(EurekaServiceApplication.class,args);
        }
    }

配置文件配置:

server:
      port: 8081
    spring:
      datasource:
        url: jdbc:mysql://localhost:3306/数据库
        username: root
        password: root
      application:
        name: user-service # 应用名称
    eureka:
      client:
        service-url: # EurekaServer地址
          defaultZone: http://127.0.0.1:10086/eureka

# 服务发现 #

启动类和服务注册一样  
如果启动不起来,就用 `@EnableDiscoveryClient`

import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    import org.springframework.cloud.client.SpringCloudApplication;
    import org.springframework.cloud.client.circuitbreaker.EnableCircuitBreaker;
    import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
    import org.springframework.cloud.client.loadbalancer.LoadBalanced;
    import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
    import org.springframework.context.annotation.Bean;
    import org.springframework.http.converter.StringHttpMessageConverter;
    import java.nio.charset.StandardCharsets;
    
    @SpringBootApplication
    //@EnableEurekaClient 表示当前项目是eureka注册中心的客户端
    @EnableDiscoveryClient  //表示是注册中心的客户端 不限于是哪个注册中心可以是eureka也可以是zookeeper 可以省略
    //@EnableCircuitBreaker
    //@SpringCloudApplication
    public class EurekaClientdiaoApplication { 
        public static void main(String[] args) { 
            SpringApplication.run(EurekaServiceApplication.class,args);
        }
         @Bean
        public RestTemplate restTemplate(){ 
            RestTemplate restTemplate = new RestTemplate();
            restTemplate.getMessageConverters().add(1,new StringHttpMessageConverter(StandardCharsets.UTF_8));
            return restTemplate;
        }
    }

配置文件基本和服务注册差不多

server:
      port: 8082
    spring:
      application:
        name: user-service # 应用名称
    eureka:
      client:
        service-url: # EurekaServer地址
          defaultZone: http://127.0.0.1:10086/eureka

来一个Controller类调用服务测试,

@RestController
    @RequestMapping("/diaoyong")
    public class ConsumerController { 
    
        @Autowired
        private RestTemplate restTemplate;
    
        @Autowired
        private DiscoveryClient discoveryClient;
    
        @GetMapping("/user/{id}")
        public User queryById(@PathVariable("id") Long id){ 
            // 根据服务id(spring.application.name)，获取服务实例列表
            List<ServiceInstance> instances = discoveryClient.getInstances("user-service");
            // 取出一个服务实例,因为我这里就一个服务
            ServiceInstance instance = instances.get(0);
            // 查询.instance.getUri()返回的只有ip+端口号,没有方法请求地址
            User user = restTemplate.getForObject(instance.getUri()+"/user/" + id, User.class);
            return user;
        }
    }

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