SpringCloud 学习笔记-Eureka注册与发现（一）

﹏ヽ暗。殇╰゛Y 2023-07-04 15:42 13阅读 0赞

## Eureka ##

Eureka Server注册中心

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM1NDE4NTE4_size_16_color_FFFFFF_t_70][]

简单的高可用，开启3个eureka 相互注册到对方上。

pom

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

yml (这里，的另外2个eureka 都填写对方的端口)

eureka:
      client:
        service-url:
          defaultZone: http://localhost:8761/eureka/,http://localhost:8763/eureka/
        register-with-eureka: false  #不把自己注册到client上
      server:
        # 自我保护机制，一个服务开关太过频繁，注册中心就一段时间内直接认为你是在的，开发环境下设置成false（实际环境要打开），防止服务挂掉，注册还在
        enable-self-preservation: false
    spring:
      application:
        name: eureka
    server:
      port: 8762

@SpringBootApplication
    @EnableEurekaServer
    public class Eureka1Application {
    
        public static void main(String[] args) {
            SpringApplication.run(Eureka1Application.class, args);
        }
    
    }

Eureka Client 服务注册

pom

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

yml

eureka:
      client:
        service-url:
          defaultZone: http://localhost:8761/eureka/,http://localhost:8762/eureka/,http://localhost:8763/eureka/
    
    spring:
      application:
        name: client-user  # 服务名称

启动类

@SpringBootApplication
    @EnableDiscoverClient
    public class Eureka1Application {
    
        public static void main(String[] args) {
            SpringApplication.run(Eureka1Application.class, args);
        }
    
    }

完整pom

<?xml version="1.0" encoding="UTF-8"?>
    <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
        <modelVersion>4.0.0</modelVersion>
        <parent>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-parent</artifactId>
            <version>2.1.6.RELEASE</version>
            <relativePath/> 
        </parent>
        <groupId>com.gray</groupId>
        <artifactId>server-register</artifactId>
        <version>0.0.1-SNAPSHOT</version>
        <name>server-register</name>
        <description>Demo project for Spring Boot</description>
    
        <properties>
            <java.version>1.8</java.version>
            <spring-cloud.version>Greenwich.SR1</spring-cloud.version>
        </properties>
    
        <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-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>
    
    </project>

## 相互通信 ##

1、RestTemplate  （通过发送url直接获取返回值）

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

@RestController
    public class HelloController {
    
        @RequestMapping("/hello")
        public String getHello(){
            return "Hello world";
        }
    }

@RestController
    @Slf4j
    public class HelloClientController {
    
        @GetMapping("/client-hello")
        public String getHello(){
            RestTemplate restTemplate = new RestTemplate();
            String response = restTemplate.getForObject("http://localhost:8080/hello",String.class);
            log.info("response={}",response);
            return response;
        }
    
    }

2、LoadBalancerClient （通过服务器id获取服务器信息）

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM1NDE4NTE4_size_16_color_FFFFFF_t_70 1][]

@RestController
    @Slf4j
    public class HelloClientController {
    
        @Autowired
        private LoadBalancerClient loadBalancerClient;
    
        @GetMapping("/client-loadBalancer")
        public String getLoadBalancer(){
            RestTemplate restTemplate = new RestTemplate();
            ServiceInstance serviceInstance = loadBalancerClient.choose("EUREKACLIENT");
            String url = String.format("http://%s:%s",serviceInstance.getHost(),serviceInstance.getPort() + "/hello");
            String response = restTemplate.getForObject(url,String.class);
            log.info("response={}",response);
            return response;
        }
    }

3、@LoadBalanced

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

@RestController
    @Slf4j
    public class HelloClientController {
    
        @Autowired
        private RestTemplate restTemplate;
    
        @GetMapping("/restTemp")
        public String getRestTemp(){
            String response = restTemplate.getForObject("http://EUREKACLIENT/hello",String.class);
            log.info("response={}",response);
            return response;
        }
    }

## Ribbon 负载均衡器 ##

涉及使用：RestTemplate、Feign、Zuul   (客户端自己的负载均衡)

功能：服务发现（通过服务名字找到所有实例）、服务选择（依据规定的方式选择实例）、服务监听（检查实效的服务，高效剔除）

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM1NDE4NTE4_size_16_color_FFFFFF_t_70 2][]

客户端指定添加均衡策略,请求localhost:8080/restTemp  (服务得开启多个，这里是放在调用方客户端的),product是服务器名称

yml

**1、随机规则（RandomRule）**

在rule的choose的时候 使用一个所有服务列表中取随机数去可用服务（upList）中取可用的服务，如果取到的服务不可用或者无此服务。

**2、线性轮训规则（RoundRobinRule）**

线性轮询和RandomRule相似，循环条件以外增加了10次的轮询限制，如果10次没有获取到可用的服务，则返回 No available alive serivces after 10 tries  from load balancer.....

**3、重试规则（RetryRule）**

RetryRule增加了一个重试机制，此机制默认使用 RoundRobinRule规则来获取服务，通知定义了一个重试时间（maxRetryMillis），如果在重试时间内没有获取到可用的服务，则重复进行获取，如果超出重试时间还未获取到则返回null。

**4、WeightedResponseTimeRule(反馈权重规则)**

该策略主要是对RoundRobinRule规则的扩展，根据实例的运行情况计算权重，并根据权重来选择实例，以达到最优的分配效果

**5、ClientConfigEnableRoundRobinRule**

内部使用RoundRobinRule规则来实现策略，但是经常继承这个类来实现高级策略的制定

**6、BestAvailableRule(选择最优的服务)**

继承了CIientConfigEnableRoundRobinRule规则，在实现时注入了负载均衡器的统计对象LoadBalacneStats ,同时在选择实例的时候利用LoadBalaceStats来统计信息来来选择满足要求的实例

**  7、PredicateBasedRule（基于预先判断的测试）**

这是一种过滤清单的一种策略，在选择服务的时候先将获取到的服务清单通过Predicate配置的过滤条件来过滤一部分服务，然后再通过线性轮训的方式来进行服务选择。

**8  AvailabilityFilteringRule（可用性过滤的规则）**

这是可用性过滤的策略，就是在选择的时候，过滤所有的Server都是可以服务正常的Server。

**9 ZoneAvoidanceRule **

域的过滤器，这个其实是ZoneAvoidancePredicate和AvailabilityPredicate的组合过滤器，同时过滤所在的域和可用性的过滤器。

# #

##    springcloud方法 ##

## 提供服务 ##

pom

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

yml

eureka:
      client:
        service-url:
          defaultZone: http://localhost:8761/eureka/,http://localhost:8762/eureka/,http://localhost:8763/eureka/
    spring:
      application:
        name: product
    server:
      port: 8081

启动类

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

开放方法

@RestController
    public class HelloController {
    
        @Value("${server.port}")
        private String msg;
    
        @RequestMapping("/hello")
        public String getHello(){
            return "Hello world port = " + msg;
        }
    }

## 使用服务 ##

pom

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

yml

eureka:
      client:
        service-url:
          defaultZone: http://localhost:8761/eureka/,http://localhost:8762/eureka/,http://localhost:8763/eureka/
    spring:
      application:
        name: product-client
    
    CLIENT:
      ribbon:
        NFLoadBalancerRuleClassName: com.netflix.loadbalancer.RoundRobinRule

启动类

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

调用接口

@FeignClient(name = "product")
    public interface UserClientBase {
    
        @RequestMapping("/hello")
        String getHello();
    }

具体调用

@RestController
    public class Hello {
    
        @Autowired
        private UserClientBase userClientBase;
    
        @GetMapping("/getMsg")
        public String getMsg(){
            return userClientBase.getHello();
        }
    }

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