1. Feign介绍
之前用到Ribbon,但是每个接口都要去拼接参数,会比较麻烦。而Feign可以理解为就是在Ribbon上加了一层封装,让我们在调用服务的时候不用处理那些麻烦的参数了
2.代码实现
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新建一个Feign服务
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pom.xml
<?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/> <!-- lookup parent from repository --> </parent> <groupId>com.pikaqiu.springcloud</groupId> <artifactId>feign</artifactId> <version>0.0.1-SNAPSHOT</version> <name>SpringCloud-Feign</name> <description>Demo project for Spring Boot</description> <properties> <java.version>1.8</java.version> <spring-cloud.version>Greenwich.SR2</spring-cloud.version> </properties> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId> </dependency> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-openfeign</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>
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application.yml
server: port: 5002 spring: application: name: feign eureka: client: service-url: defaultZone: http://eureka-server1:3001/eureka/,http://eureka-server2:3002/eureka/ instance: instance-id: Feign
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在项目启动类中,添加注解@EnableEurekaClient 和 @EnableFeignClients
@SpringBootApplication @EnableEurekaClient @EnableFeignClients public class SpringCloudFeignApplication { public static void main(String[] args) { SpringApplication.run(SpringCloudFeignApplication.class, args); } }
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接下来是核心的接口定义。新建一个接口FeignService.java。其中@FeignClient参数对应客户端名称
/** * @author 吕梁山 * @date 2019/7/17 */ @FeignClient("eureka-client") public interface FeignService { @RequestMapping("test") String test(String userName); }
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现在eurek中可以看到已经注册了两个client服务一个feign服务!
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测试 访问
http://localhost:5002/test?userName=测试
会发现Feign会去轮询访问两个client服务
此次服务端口号:4001,接收到的参数:测试 此次服务端口号:4002,接收到的参数:测试
3. 更换负载均衡策略
Feign默认的策略是轮训,也就是挨个访问每个服务,也可以自己更换策略或者已定义策略,com.netflix.loadbalancer包下有很多种定义好的策略,可以自己选择,同样可以参照写好的策略类自己写一个策略类
eureka-client: ribbon: NFLoadBalancerRuleClassName: com.netflix.loadbalancer.RandomRule
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eureka-client 需要进行负载均衡的服务name
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NFLoadBalancerRuleClassName 策略类路径,如果是自定义就写自己项目里的路径