Spring Cloud Alibaba 创建服务消费者(Feign)
上篇文章， Spring Cloud Alibaba 创建服务消费者（RestTemplate + LoadBalancerClient），
我们一起学习了 使用 RestTemplate + LoadBalancerClient 的方式 去创建服务消费者，但是依旧显得繁琐，本文，我们将结合使用 spring-cloud-openfeign 来创建服务消费者，简化消费调用…
一起开始吧
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概述
Feign 是一个声明式的伪 Http 客户端，它使得写 Http 客户端变得更简单。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，可使用 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">
<parent>
<artifactId>sous</artifactId>
<groupId>com.yinzhong</groupId>
<version>1.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>openfeign</artifactId>
<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>
<version>2.4.5</version>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
<version>2.4.5</version>
</dependency>
<!-- Spring Boot End -->
<!-- Spring Cloud Begin -->
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-openfeign</artifactId>
<version>3.0.3</version>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-loadbalancer</artifactId>
<version>3.0.2</version>
</dependency>
<dependency>
<groupId>com.alibaba.cloud</groupId>
<artifactId>spring-cloud-starter-alibaba-sentinel</artifactId>
<version>2.2.3.RELEASE</version>
</dependency>
<!-- Spring Cloud End -->
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<configuration>
<mainClass>com.yinzhong.openfeign.OpenFeignApplication</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.yinzhong.openfeign;
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 OpenFeignApplication {
public static void main(String[] args) {
SpringApplication.run(OpenFeignApplication.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：
@FeignClient(value = “customs”)
public interface FeignService {
@GetMapping(value = "/pay/aaa")
String test();
}
Controller
@RestController
public class NacosConsumerFeignController {
@Autowired
private FeignService FeignService;
@GetMapping(value = "/test/hi")
public String test(HttpServletRequest request) {
return FeignService.test();
}
}
application.yml
spring:
application:
name: openfeign
cloud:
nacos:
discovery:
server-addr: 127.0.0.1:8848
server:
port: 9092
management:
endpoints:
web:
exposure:
include: "*"测试负载均衡
- idea启动多个实例
在这里选√
然后修改yml文件里的端口号再启动一个就可以了。
- 启动多个
consumer-provider实例，效果图如下：
- 修改
consumer-provider项目中的Controller代码，用于确定负载均衡生效
package com.wsl.hello.provider.controller;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;
@RestController
public class NacosProviderController {
@Value("${server.port}")
private String port;
@GetMapping(value = "/test/{message}")
public String test(@PathVariable String message) {
return "Hello Nacos Discovery " + message + " i am from port " + port;
}
}
在浏览器上多次访问 http://localhost:9092/test/hi，浏览器交替显示：
Hello Nacos Discovery Hi Feign i am from port 8081
Hello Nacos Discovery Hi Feign i am from port 8082
