五分钟带你玩转springcloudNetflix（四）服务间调用
【摘要】
上文我们把我们项目注册到服务器上了，但是我们会使用A服务调用B服务,那么就会使用服务的调用，这里有两种方式ribbon和feign,我们分别介绍。
ribbon
ribbon说白了就是使用restTemplate。下面上代码
首先pom文件
<?xml version="1.0" encoding="UTF-8"?>...
上文我们把我们项目注册到服务器上了，但是我们会使用A服务调用B服务,那么就会使用服务的调用，这里有两种方式ribbon和feign,我们分别介绍。
ribbon
ribbon说白了就是使用restTemplate。下面上代码
首先pom文件
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<?xml version="1.0" encoding="UTF-8"?>
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<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
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<modelVersion>4.0.0</modelVersion>
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<parent>
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<groupId>org.springframework.boot</groupId>
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<artifactId>spring-boot-starter-parent</artifactId>
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<version>2.2.5.RELEASE</version>
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<relativePath/> <!-- lookup parent from repository -->
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</parent>
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<groupId>com.baocl</groupId>
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<artifactId>eureka-consumer</artifactId>
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<version>0.0.1-SNAPSHOT</version>
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<name>eureka-consumer</name>
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<description>Demo project for Spring Boot</description>
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<properties>
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<java.version>1.8</java.version>
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<spring-cloud.version>Hoxton.SR1</spring-cloud.version>
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</properties>
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<dependencies>
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<dependency>
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<groupId>org.springframework.boot</groupId>
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<artifactId>spring-boot-starter-web</artifactId>
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</dependency>
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<dependency>
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<groupId>org.springframework.cloud</groupId>
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<artifactId>spring-cloud-starter-netflix-ribbon</artifactId>
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</dependency>
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<dependency>
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<groupId>org.springframework.cloud</groupId>
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<artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
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</dependency>
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<dependency>
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<groupId>org.springframework.boot</groupId>
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<artifactId>spring-boot-starter-test</artifactId>
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<scope>test</scope>
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<exclusions>
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<exclusion>
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<groupId>org.junit.vintage</groupId>
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<artifactId>junit-vintage-engine</artifactId>
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</exclusion>
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</exclusions>
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</dependency>
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</dependencies>
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<dependencyManagement>
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<dependencies>
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<dependency>
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<groupId>org.springframework.cloud</groupId>
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<artifactId>spring-cloud-dependencies</artifactId>
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<version>${spring-cloud.version}</version>
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<type>pom</type>
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<scope>import</scope>
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</dependency>
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</dependencies>
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</dependencyManagement>
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<build>
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<plugins>
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<plugin>
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<groupId>org.springframework.boot</groupId>
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<artifactId>spring-boot-maven-plugin</artifactId>
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</plugin>
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</plugins>
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</build>
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</project>
然后EurekaConsumerApplication类
需要在新建RestTemplate的bean
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package com.cloud;
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import org.springframework.boot.SpringApplication;
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import org.springframework.boot.autoconfigure.SpringBootApplication;
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import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
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import org.springframework.cloud.client.loadbalancer.LoadBalanced;
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import org.springframework.context.annotation.Bean;
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import org.springframework.web.client.RestTemplate;
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@SpringBootApplication
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@EnableDiscoveryClient
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public class EurekaConsumerApplication {
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@Bean
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@LoadBalanced // ribbon注解
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public RestTemplate restTemplate() {
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return new RestTemplate();
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}
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public static void main(String[] args) {
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SpringApplication.run(EurekaConsumerApplication.class, args);
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}
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}
DcController
新建接口 调用上文服务
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import org.springframework.beans.factory.annotation.Autowired;
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import org.springframework.cloud.client.discovery.DiscoveryClient;
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import org.springframework.cloud.client.loadbalancer.LoadBalancerClient;
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import org.springframework.http.ResponseEntity;
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import org.springframework.web.bind.annotation.GetMapping;
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import org.springframework.web.bind.annotation.RequestMapping;
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import org.springframework.web.bind.annotation.RestController;
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import org.springframework.web.client.RestTemplate;
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@RestController
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@RequestMapping("/eureka1")
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public class DcController {
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@Autowired
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LoadBalancerClient loadBalancerClient;
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@Autowired
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RestTemplate restTemplate;
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@Autowired
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DiscoveryClient discoveryClient;
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@GetMapping("/consumer")
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public ResponseEntity<String> dc() {
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//String url = "http://eureka-client/aaa/dc?dk=3001";
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String url = "http://EUREKA-CLIENT/aaa/dc?dk=3001";
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System.out.println(url);
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// ServiceInstance serviceInstance =
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// loadBalancerClient.choose("eureka-client");// 获取服务提供者信息
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// // String url = "http://localhost:" + serviceInstance.getPort() + "/aaa/dc";
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// System.out.println(serviceInstance.getPort() );
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// System.out.println(url);
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// ResponseEntity r = restTemplate.getForEntity("http://eureka-client/aaa/dc",
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// String.class);
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// System.out.println("r.getHeaders().getHost():"+r.getHeaders().getHost());
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// System.out.println("r.getHeaders().getLocation():"+r.getHeaders().getLocation());
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// System.out.println("r.getHeaders().getOrigin():"+r.getHeaders().getOrigin());
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return restTemplate.getForEntity(url, String.class); // ribbon应用
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}
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}
有一个坑 在调用时候需要
String url = "http://eureka-client/aaa/dc?dk=3001";
而不是
String url = "http://localhost:2002/aaa/dc?dk=3001";
否则会报错。
java.lang.IllegalStateException: No instances available for localhost
最后是配置文件application.yml
这里我们使用.yml文件 都是基础配置
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eureka:
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client:
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registery-fetch-interval-seconds: 5000
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serviceUrl:
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defaultZone: http://localhost:1001/eureka/
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eureka-client:
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ribbon:
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NFLoadBalancerRuleClassName: com.netflix.loadbalancer.RandomRule
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server:
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port: 3001
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spring:
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application:
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name: eureka-consumer
输入http://localhost:3001/eureka1/consumer就可以调用到上文的client服务了，同时还会使用顺序调用负载均衡策略。
feign
EurekaConsumerFeignApplication
首先在EurekaConsumerFeignApplication使用@EnableFeignClients中开启feign
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import org.springframework.boot.SpringApplication;
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import org.springframework.boot.autoconfigure.SpringBootApplication;
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import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
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import org.springframework.cloud.openfeign.EnableFeignClients;
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@EnableFeignClients
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@EnableDiscoveryClient
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@SpringBootApplication
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public class EurekaConsumerFeignApplication {
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public static void main(String[] args) {
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SpringApplication.run(EurekaConsumerFeignApplication.class, args);
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}
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}
新建一个接口DcClient
配置调用其他服务的名称和接口名称
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import org.springframework.cloud.openfeign.FeignClient;
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import org.springframework.web.bind.annotation.GetMapping;
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@FeignClient(name = "eureka-client")
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public interface DcClient {
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@GetMapping("/aaa/dc?dk=3002")
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String consumer();
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@GetMapping("/aaa/dc?dk=3002")
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String consumer2();
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}
DcController
业务接口的书写 同时注入dcClient调用其他服务
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import org.springframework.beans.factory.annotation.Autowired;
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import org.springframework.web.bind.annotation.GetMapping;
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import org.springframework.web.bind.annotation.RequestMapping;
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import org.springframework.web.bind.annotation.RestController;
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import com.cloud.DcClient;
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@RestController
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@RequestMapping("/eureka2")
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public class DcController {
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@Autowired
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DcClient dcClient;
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@GetMapping("/consumer")
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public String dc() {
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return dcClient.consumer();
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}
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}
application.properties
基础配置
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spring.application.name=eureka-consumer-feign
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server.port=3002
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eureka.client.serviceUrl.defaultZone=http://localhost:1001/eureka/
pom文件
版本问题一定要控制！！！！
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<?xml version="1.0" encoding="UTF-8"?>
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<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 https://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>2.2.5.RELEASE</version>
-
<relativePath/> <!-- lookup parent from repository -->
-
</parent>
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<groupId>com.baocl</groupId>
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<artifactId>eureka-consumer-feign</artifactId>
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<version>0.0.1-SNAPSHOT</version>
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<name>eureka-consumer-feign</name>
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<description>Demo project for Spring Boot</description>
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<properties>
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<java.version>1.8</java.version>
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<spring-cloud.version>Hoxton.SR1</spring-cloud.version>
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</properties>
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<dependencies>
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<dependency>
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<groupId>org.springframework.boot</groupId>
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<artifactId>spring-boot-starter-web</artifactId>
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</dependency>
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<dependency>
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<groupId>org.springframework.cloud</groupId>
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<artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
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</dependency>
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<dependency>
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<groupId>org.springframework.cloud</groupId>
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<artifactId>spring-cloud-starter-feign</artifactId>
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<version>1.4.7.RELEASE</version>
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</dependency>
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<dependency>
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<groupId>org.springframework.boot</groupId>
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<artifactId>spring-boot-starter-test</artifactId>
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<scope>test</scope>
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<exclusions>
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<exclusion>
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<groupId>org.junit.vintage</groupId>
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<artifactId>junit-vintage-engine</artifactId>
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</exclusion>
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</exclusions>
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</dependency>
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</dependencies>
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<dependencyManagement>
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<dependencies>
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<dependency>
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<groupId>org.springframework.cloud</groupId>
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<artifactId>spring-cloud-dependencies</artifactId>
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<version>${spring-cloud.version}</version>
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<type>pom</type>
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<scope>import</scope>
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</dependency>
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</dependencies>
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</dependencyManagement>
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<build>
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<plugins>
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<plugin>
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<groupId>org.springframework.boot</groupId>
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<artifactId>spring-boot-maven-plugin</artifactId>
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</plugin>
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</plugins>
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</build>
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</project>
这里有一个坑 就是版本问题，有时会报错
org.springframework.beans.factory.BeanDefinitionStoreException: Failed to read candidate component class: file [F:\workspace\springcloud\tse9\eureka-consumer-feign\target\classes\com\cloud\DcClient.class]; nested exception is org.springframework.core.annotation.AnnotationConfigurationException: Attribute 'value' in annotation [org.springframework.cloud.netflix.feign.FeignClient] must be declared as an @AliasFor 'serviceId', not 'name'.
解决办法http://www.pianshen.com/article/2239869942/
然后调用http://localhost:3002/eureka2/consumer 可以发现接口掉通了 帮帮哒
ribbon和Eureka整合原理
基本流程就是 客户端从eureka中获取到缓存的服务列表，获取到目的服务的信息，然后通过自身的负载均衡策略，去调用对应的服务
负载均衡策略
BestAvailableRule 选择一个最小的并发请求的server. AvailabilityFilteringRule 过滤掉那些因为一直连接失败的被标记为circuit tripped的后端server，并过滤掉那些高并发的的后端server（active connections 超过配置的阈值）. WeightedResponseTimeRule 根据响应时间分配一个weight，响应时间越长，weight越小，被选中的可能性越低. RetryRule 对选定的负载均衡策略机上重试机制. RoundRobinRule roundRobin方式轮询选择server. RandomRule 随机选择一个server. ZoneAvoidanceRule 复合判断server所在区域的性能和server的可用性选择server.
文章来源: baocl.blog.csdn.net，作者：小黄鸡1992，版权归原作者所有，如需转载，请联系作者。
原文链接：baocl.blog.csdn.net/article/details/104738600
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