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blog.csdn.net/forezp/arti…
本文出自方志朋的博客
上一篇文章，讲述了通过restTemplate+ribbon去消费服务，这篇文章主要讲述通过feign去消费服务。
一、Feign简介
Feign是一个声明式的web服务客户端，它使得写web服务变得更简单。使用Feign,只需要创建一个接口并注解。它具有可插拔的注解特性，包括Feign 注解和JAX-RS注解。Feign同时支持可插拔的编码器和解码器。Spring cloud对Spring mvc添加了支持，同时在spring web中次用相同的HttpMessageConverter。当我们使用feign的时候，spring cloud 整和了Ribbon和eureka去提供负载均衡。
简而言之：
- feign采用的是接口加注解
- feign 整合了ribbon
二、准备工作
继续用上一节的工程： 启动eureka-server，端口为8761; 启动service-hi 两次，端口分别为8762 、8773.
三、创建一个feign的服务
创建一个spring-boot工程，取名为：serice-feign,它的pom文件为：
<?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>
<groupId>com.forezp</groupId>
<artifactId>service-feign</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<name>service-feign</name>
<description>Demo project for Spring Boot</description>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.2.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-eureka</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-feign</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</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>Dalston.RC1</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>
<repositories>
<repository>
<id>spring-milestones</id>
<name>Spring Milestones</name>
<url>https://repo.spring.io/milestone</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</repository>
</repositories>
</project>向服务注册中心注册它自己，这时service-ribbon既是服务提供者，也是服务消费者,配置文件application.yml
eureka:
client:
serviceUrl:
defaultZone: http://localhost:8761/eureka/
server:
port: 8765
spring:
application:
name: service-feign在程序的入口类，需要通过注解@EnableFeignClients来开启feign:
@SpringBootApplication
@EnableDiscoveryClient
@EnableFeignClients
public class ServiceFeignApplication {
public static void main(String[] args) {
SpringApplication.run(ServiceFeignApplication.class, args);
}
}定义一个feign接口类,通过@ FeignClient（“服务名”），来指定调用哪个服务：
/**
* Created by fangzhipeng on 2017/4/6.
*/
@FeignClient(value = "service-hi")
public interface SchedualServiceHi {
@RequestMapping(value = "/hi",method = RequestMethod.GET)
String sayHiFromClientOne(@RequestParam(value = "name") String name);
}在web层的controllrt:
@RestController
public class HiController {
@Autowired
SchedualServiceHi schedualServiceHi;
@RequestMapping(value = "/hi",method = RequestMethod.GET)
public String sayHi(@RequestParam String name){
return schedualServiceHi.sayHiFromClientOne(name);
}
}访问http://localhost:8765/hi?name=forezp,浏览器交替显示：
hi forezp,i am from port:8762
hi forezp,i am from port:8763
四、更改feign的配置
在声明feignclient的时候，不仅要指定服务名，同时需要制定服务配置类：
@FeignClient(name = "stores", configuration = FooConfiguration.class)
public interface StoreClient {
//..
}重写配置，需要加@Configuration注解，并重写下面的两个bean,栗子：
@Configuration
public class FooConfiguration {
@Bean
public Contract feignContractg() {
return new feign.Contract.Default();
}
@Bean
public BasicAuthRequestInterceptor basicAuthRequestInterceptor() {
return new BasicAuthRequestInterceptor("user", "password");
}
}本文源码下载：
github.com/forezp/Spri…
