Feign 是一个声明式的的伪Http客户端，他使得写Http客户端变得更加简单。使用Feign，只需要创建一个接口并注解。他具有可插拔的注解特性，可以使用Feign注解和JAX-RS注解。Feign支持可插拔的编码器和解码器。Feign默认集成了Ribbon，Nacos也很好的兼容了Feign，默认实现了负载均衡的效果。
Feign 采用的是基于接口的注解
Feign整合了Ribbon
POm
创建一个工程名为:hello-spring-cloud-alibaba-nacos-consumer-feign的服务消费者项目，pom.xml 配置如下：
<?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>com.funtl</groupId>
<artifactId>hello-spring-cloud-alibaba-dependencies</artifactId>
<version>1.0.0-SNAPSHOT</version>
<relativePath>../hello-spring-cloud-alibaba-dependencies/pom.xml</relativePath>
</parent>
<artifactId>hello-spring-cloud-alibaba-nacos-consumer-feign</artifactId>
<packaging>jar</packaging>
<name>hello-spring-cloud-alibaba-nacos-consumer-feign</name>
<url>http://www.funtl.com</url>
<inceptionYear>2018-Now</inceptionYear>
<dependencies>
<!-- Spring Boot Begin -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-actuator</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<!-- Spring Boot End -->
<!-- Spring Cloud Begin -->
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-openfeign</artifactId>
</dependency>
<!-- Spring Cloud End -->
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<configuration>
<mainClass>com.funtl.hello.spring.cloud.alibaba.nacos.consumer.feign.NacosConsumerFeignApplication</mainClass>
</configuration>
</plugin>
</plugins>
</build>
</project>
主要增加了： org.springframework.cloud:spring-cloud-starter-openfeign 依赖
Application
通过 @EnableFeignClients 注解开启 Feign 功能
package com.funtl.hello.spring.cloud.alibaba.nacos.consumer.feign;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.openfeign.EnableFeignClients;
@SpringBootApplication
@EnableDiscoveryClient
@EnableFeignClients
public class NacosConsumerFeignApplication {
public static void main(String[] args) {
SpringApplication.run(NacosConsumerFeignApplication.class, args);
}
}
创建Feign接口：
通过 @FeignClient("服务名”)注解来指定调用哪个服务。代码如下：
package com.funtl.hello.spring.cloud.alibaba.nacos.consumer.feign.service;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
@FeignClient(value = "nacos-provider")
public interface EchoService {
@GetMapping(value = "/echo/{message}")
String echo(@PathVariable("message") String message);
}
controller
package com.funtl.hello.spring.cloud.alibaba.nacos.consumer.feign.controller;
import com.funtl.hello.spring.cloud.alibaba.nacos.consumer.feign.service.EchoService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
@RestController
public class NacosConsumerFeignController {
@Autowired
private EchoService echoService;
@GetMapping(value = "/echo/hi")
public String echo() {
return echoService.echo("Hi Feign");
}
}
application.yml
spring:
application:
name: nacos-consumer-feign
cloud:
nacos:
discovery:
server-addr: 127.0.0.1:8848
server:
port: 9092
management:
endpoints:
web:
exposure:
include: "*"
启动工程：
通过浏览器访问http://localhost:8848/nacos,即nacos Server网址
image
你会发现多了一个名为 nacos-consumer-feign 的服务
这时打开 http://localhost:9092/echo/hi, 你会在浏览器上看到
Hello Nacos Discovery Hi Feign
测试负载均衡
启动多个 consumer-provider 实例，效果图如下：
image
修改 consumer-provider 项目中的Controller 代码，用于确定父子啊均衡生效;
package com.funtl.hello.spring.cloud.alibaba.nacos.provider;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;
@SpringBootApplication
@EnableDiscoveryClient
public class NacosProviderApplication {
public static void main(String[] args) {
SpringApplication.run(NacosProviderApplication.class, args);
}
@Value("${server.port}")
private String port;
@RestController
public class EchoController {
@GetMapping(value = "/echo/{message}")
public String echo(@PathVariable String message) {
return "Hello Nacos Discovery " + message + " i am from port " + port;
}
}
}
在浏览器上多次访问 http://localhost:9002/echo/hi; 浏览器交替显示：
