服务消费者（Feign-上）

佚名 6年前 (2019-04-16) 随笔 643人围观抢沙发百度已收录

上一篇文章，讲述了Ribbon去做负载请求的服务消费者，本章讲述声明性REST客户端：Feign的简单使用方式

- Feign简介

Feign是一个声明式的Web服务客户端。这使得Web服务客户端的写入更加方便。它具有可插拔注释支持，包括Feign注释和JAX-RS注释。Feign还支持可插拔编码器和解码器。Spring Cloud增加了对Spring MVC注释的支持，并HttpMessageConverters在Spring Web中使用了默认使用的相同方式。Spring Cloud集成了Ribbon和Eureka，在使用Feign时提供负载平衡的http客户端。

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官方文档：http://cloud.spring.io/spring-cloud-static/Dalston.SR2/#spring-cloud-feign

- 准备工作

1.启动Consul，所有文章都将以Consul作为服务注册中心

2.创建 battcn-feign-hello，battcn-feign-hi

battcn-feign-hello

- pom.xml

<dependencies>
 <dependency>
 <groupId>org.springframework.cloud</groupId>
 <artifactId>spring-cloud-starter-consul-discovery</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>
</dependencies>

- BattcnFeignHelloApplication.java

@SpringBootApplication
@EnableDiscoveryClient
public class BattcnFeignHelloApplication {

 public static void main(String[] args) {
 SpringApplication.run(BattcnFeignHelloApplication.class, args);
 }
}

创建一个打招呼的的Controller

- HelloController.java

@RestController
@RequestMapping("/hello")
public class HelloController {
 
 @ResponseStatus(HttpStatus.OK)
 @GetMapping
 public String findStudentByName(@RequestParam("name") String name) {
 // TODO：不做具体代码实现，只打印Log
 return "挽歌- My Name's" + name;
 }
}

- bootstrap.yml

server:
 port: 8765

spring:
 application:
 name: battcn-feign-hello
 cloud:
 consul:
 host: localhost
 port: 8500
 enabled: true
 discovery:
 enabled: true
 prefer-ip-address: true

访问：http://localhost:8765/hello?name=Levin

结果：挽歌- My Name's Levin 表示我们第一个服务运行一切正常

battcn-feign-hi

- pom.xml

<dependencies>
 <dependency>
 <groupId>org.springframework.cloud</groupId>
 <artifactId>spring-cloud-starter-feign</artifactId>
 </dependency>
 <dependency>
 <groupId>org.springframework.cloud</groupId>
 <artifactId>spring-cloud-starter-consul-discovery</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>
</dependencies>

- BattcnFeignHiApplication.java

@EnableDiscoveryClient
@EnableFeignClients(basePackages = {"com.battcn.client"})
@SpringBootApplication
public class BattcnFeignHiApplication {

 public static void main(String[] args) {
 SpringApplication.run(BattcnFeignHiApplication.class, args);
 }
}

- HelloClient.java

创建一个声明式FeignClient的接口 HelloClient

@FeignClient(name = "battcn-feign-hello")
public interface HelloClient {

/** 
 * 在新版本中，Feign 已经可以解析 RestFul 标准的接口API，比如GET POST DELETE PATCH PUT 
 * 旧版中
 * @RequestMapping(method = RequestMethod.GET, value = "/hello")
 * 或者是
 * @RequestMapping(method = RequestMethod.POST, value = "/hello")
 * 
 * 早期文章：http://blog.battcn.com/2017/07/07/springcloud-feign-analysis/
 * /
 @ResponseStatus(HttpStatus.OK)
 @GetMapping("/hello")
 String findStudentByName(@RequestParam("name") String name);
}

- HiController.java

@RestController
@RequestMapping("/hi")
public class HiController {

 @Autowired
 HelloClient helloClient;

 @ResponseStatus(HttpStatus.OK)
 @GetMapping
 public String find(@RequestParam("name") String name) {
 // TODO：只是演示Feign调用的方法
 return "Hi," + helloClient.findStudentByName(name);
 }
}

- bootstrap.yml

server:
 port: 8766

spring:
 application:
 name: battcn-feign-hi
 cloud:
 consul:
 host: localhost
 port: 8500
 enabled: true
 discovery:
 enabled: true
 prefer-ip-address: true