Spring Cloud入门-OpenFeign服务消费者(Hoxton版本)

墨蓝 2021-09-21 01:20 336阅读 0赞

### 文章目录 ###

*   *  Spring Cloud入门系列汇总
     *  摘要
     *  Feign简介
     *  创建一个feign-service模块
     *   *  在pom.xml中添加相关依赖
         *  在application.yml中进行配置
         *  在启动类上添加@EnableFeignClients注解来启用Feign的客户端功能
         *  添加UserService接口完成对user-service服务的接口绑定
         *  添加UserFeignController调用UserService实现服务调用
     *  负载均衡功能演示
     *  Feign中的服务降级
     *   *  添加服务降级实现类UserFallbackService
         *  修改UserService接口，设置服务降级处理类为UserFallbackService
         *  修改application.yml，开启Hystrix功能
     *  服务降级功能演示
     *  日志打印功能
     *   *  日志级别
         *  通过配置开启更为详细的日志
         *  在application.yml中配置需要开启日志的Feign客户端
         *  查看日志
     *  Feign的常用配置
     *   *  Feign自己的配置
         *  Feign中的Ribbon配置
         *  Feign中的Hystrix配置
     *  使用到的模块
     *  项目源码地址

> 项目使用的Spring Cloud为Hoxton版本，Spring Boot为2.2.2.RELEASE版本

## Spring Cloud入门系列汇总 ##

<table> 
 <thead> 
  <tr> 
   <th>序号</th> 
   <th>内容</th> 
   <th>链接地址</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td>1</td> 
   <td>Spring Cloud入门-十分钟了解Spring Cloud</td> 
   <td><a href="https://blog.csdn.net/ThinkWon/article/details/103715146" rel="nofollow">https://blog.csdn.net/ThinkWon/article/details/103715146</a></td> 
  </tr> 
  <tr> 
   <td>2</td> 
   <td>Spring Cloud入门-Eureka服务注册与发现(Hoxton版本)</td> 
   <td><a href="https://blog.csdn.net/ThinkWon/article/details/103726655" rel="nofollow">https://blog.csdn.net/ThinkWon/article/details/103726655</a></td> 
  </tr> 
  <tr> 
   <td>3</td> 
   <td>Spring Cloud入门-Ribbon服务消费者(Hoxton版本)</td> 
   <td><a href="https://blog.csdn.net/ThinkWon/article/details/103729080" rel="nofollow">https://blog.csdn.net/ThinkWon/article/details/103729080</a></td> 
  </tr> 
  <tr> 
   <td>4</td> 
   <td>Spring Cloud入门-Hystrix断路器(Hoxton版本)</td> 
   <td><a href="https://blog.csdn.net/ThinkWon/article/details/103732497" rel="nofollow">https://blog.csdn.net/ThinkWon/article/details/103732497</a></td> 
  </tr> 
  <tr> 
   <td>5</td> 
   <td>Spring Cloud入门-Hystrix Dashboard与Turbine断路器监控(Hoxton版本)</td> 
   <td><a href="https://blog.csdn.net/ThinkWon/article/details/103734664" rel="nofollow">https://blog.csdn.net/ThinkWon/article/details/103734664</a></td> 
  </tr> 
  <tr> 
   <td>6</td> 
   <td>Spring Cloud入门-OpenFeign服务消费者(Hoxton版本)</td> 
   <td><a href="https://blog.csdn.net/ThinkWon/article/details/103735751" rel="nofollow">https://blog.csdn.net/ThinkWon/article/details/103735751</a></td> 
  </tr> 
  <tr> 
   <td>7</td> 
   <td>Spring Cloud入门-Zuul服务网关(Hoxton版本)</td> 
   <td><a href="https://blog.csdn.net/ThinkWon/article/details/103738851" rel="nofollow">https://blog.csdn.net/ThinkWon/article/details/103738851</a></td> 
  </tr> 
  <tr> 
   <td>8</td> 
   <td>Spring Cloud入门-Config分布式配置中心(Hoxton版本)</td> 
   <td><a href="https://blog.csdn.net/ThinkWon/article/details/103739628" rel="nofollow">https://blog.csdn.net/ThinkWon/article/details/103739628</a></td> 
  </tr> 
  <tr> 
   <td>9</td> 
   <td>Spring Cloud入门-Bus消息总线(Hoxton版本)</td> 
   <td><a href="https://blog.csdn.net/ThinkWon/article/details/103753372" rel="nofollow">https://blog.csdn.net/ThinkWon/article/details/103753372</a></td> 
  </tr> 
  <tr> 
   <td>10</td> 
   <td>Spring Cloud入门-Sleuth服务链路跟踪(Hoxton版本)</td> 
   <td><a href="https://blog.csdn.net/ThinkWon/article/details/103753896" rel="nofollow">https://blog.csdn.net/ThinkWon/article/details/103753896</a></td> 
  </tr> 
  <tr> 
   <td>11</td> 
   <td>Spring Cloud入门-Consul服务注册发现与配置中心(Hoxton版本)</td> 
   <td><a href="https://blog.csdn.net/ThinkWon/article/details/103756139" rel="nofollow">https://blog.csdn.net/ThinkWon/article/details/103756139</a></td> 
  </tr> 
  <tr> 
   <td>12</td> 
   <td>Spring Cloud入门-Gateway服务网关(Hoxton版本)</td> 
   <td><a href="https://blog.csdn.net/ThinkWon/article/details/103757927" rel="nofollow">https://blog.csdn.net/ThinkWon/article/details/103757927</a></td> 
  </tr> 
  <tr> 
   <td>13</td> 
   <td>Spring Cloud入门-Admin服务监控中心(Hoxton版本)</td> 
   <td><a href="https://blog.csdn.net/ThinkWon/article/details/103758697" rel="nofollow">https://blog.csdn.net/ThinkWon/article/details/103758697</a></td> 
  </tr> 
  <tr> 
   <td>14</td> 
   <td>Spring Cloud入门-Oauth2授权的使用(Hoxton版本)</td> 
   <td><a href="https://blog.csdn.net/ThinkWon/article/details/103761687" rel="nofollow">https://blog.csdn.net/ThinkWon/article/details/103761687</a></td> 
  </tr> 
  <tr> 
   <td>15</td> 
   <td>Spring Cloud入门-Oauth2授权之JWT集成(Hoxton版本)</td> 
   <td><a href="https://blog.csdn.net/ThinkWon/article/details/103763364" rel="nofollow">https://blog.csdn.net/ThinkWon/article/details/103763364</a></td> 
  </tr> 
  <tr> 
   <td>16</td> 
   <td>Spring Cloud入门-Oauth2授权之基于JWT完成单点登录(Hoxton版本)</td> 
   <td><a href="https://blog.csdn.net/ThinkWon/article/details/103766368" rel="nofollow">https://blog.csdn.net/ThinkWon/article/details/103766368</a></td> 
  </tr> 
  <tr> 
   <td>17</td> 
   <td>Spring Cloud入门-Nacos实现注册和配置中心(Hoxton版本)</td> 
   <td><a href="https://blog.csdn.net/ThinkWon/article/details/103769680" rel="nofollow">https://blog.csdn.net/ThinkWon/article/details/103769680</a></td> 
  </tr> 
  <tr> 
   <td>18</td> 
   <td>Spring Cloud入门-Sentinel实现服务限流、熔断与降级(Hoxton版本)</td> 
   <td><a href="https://blog.csdn.net/ThinkWon/article/details/103770879" rel="nofollow">https://blog.csdn.net/ThinkWon/article/details/103770879</a></td> 
  </tr> 
  <tr> 
   <td>19</td> 
   <td>Spring Cloud入门-Seata处理分布式事务问题(Hoxton版本)</td> 
   <td><a href="https://blog.csdn.net/ThinkWon/article/details/103786102" rel="nofollow">https://blog.csdn.net/ThinkWon/article/details/103786102</a></td> 
  </tr> 
  <tr> 
   <td>20</td> 
   <td>Spring Cloud入门-汇总篇(Hoxton版本)</td> 
   <td><a href="https://blog.csdn.net/ThinkWon/article/details/103786588" rel="nofollow">https://blog.csdn.net/ThinkWon/article/details/103786588</a></td> 
  </tr> 
 </tbody> 
</table>

## 摘要 ##

Spring Cloud OpenFeign 是声明式的服务调用工具，它整合了Ribbon和Hystrix，拥有负载均衡和服务容错功能，本文将对其用法进行详细介绍。

## Feign简介 ##

Feign是声明式的服务调用工具，我们只需创建一个接口并用注解的方式来配置它，就可以实现对某个服务接口的调用，简化了直接使用RestTemplate来调用服务接口的开发量。Feign具备可插拔的注解支持，同时支持Feign注解、JAX-RS注解及SpringMvc注解。当使用Feign时，Spring Cloud集成了Ribbon和Eureka以提供负载均衡的服务调用及基于Hystrix的服务容错保护功能。

## 创建一个feign-service模块 ##

> 这里我们创建一个feign-service模块来演示feign的常用功能。

### 在pom.xml中添加相关依赖 ###

<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>

### 在application.yml中进行配置 ###

server:
      port: 8701
    
    spring:
      application:
        name: feign-service
    
    eureka:
      client:
        register-with-eureka: true
        fetch-registry: true
        service-url:
          defaultZone: http://localhost:8001/eureka/

### 在启动类上添加@EnableFeignClients注解来启用Feign的客户端功能 ###

@EnableFeignClients
    @EnableDiscoveryClient
    @SpringBootApplication
    public class FeignServiceApplication { 
    
        public static void main(String[] args) { 
            SpringApplication.run(FeignServiceApplication.class, args);
        }
    
    }

### 添加UserService接口完成对user-service服务的接口绑定 ###

> 我们通过@FeignClient注解实现了一个Feign客户端，其中的value为user-service表示这是对user-service服务的接口调用客户端。我们可以回想下user-service中的UserController，只需将其改为接口，保留原来的SpringMvc注释即可。

@FeignClient(value = "user-service", fallback = UserFallbackService.class)
    public interface UserService { 
    
        @PostMapping("/user/insert")
        Result insert(@RequestBody User user);
    
        @GetMapping("/user/{id}")
        Result<User> getUser(@PathVariable Long id);
    
        @GetMapping("/user/listUsersByIds")
        Result<List<User>> listUsersByIds(@RequestParam List<Long> ids);
    
        @GetMapping("/user/getByUsername")
        Result<User> getByUsername(@RequestParam String username);
    
        @PostMapping("/user/update")
        Result update(@RequestBody User user);
    
        @PostMapping("/user/delete/{id}")
        Result delete(@PathVariable Long id);
    
    }

### 添加UserFeignController调用UserService实现服务调用 ###

@RestController
    @RequestMapping("/user")
    public class UserFeignController { 
    
        @Autowired
        private UserService userService;
    
        @PostMapping("/insert")
        public Result insert(@RequestBody User user) { 
            return userService.insert(user);
        }
    
        @GetMapping("/{id}")
        public Result<User> getUser(@PathVariable Long id) { 
            return userService.getUser(id);
        }
    
        @GetMapping("/listUsersByIds")
        public Result<List<User>> listUsersByIds(@RequestParam List<Long> ids) { 
            return userService.listUsersByIds(ids);
        }
    
        @GetMapping("/getByUsername")
        public Result<User> getByUsername(@RequestParam String username) { 
            return userService.getByUsername(username);
        }
    
        @PostMapping("/update")
        public Result update(@RequestBody User user) { 
            return userService.update(user);
        }
    
        @PostMapping("/delete/{id}")
        public Result delete(@PathVariable Long id) { 
            return userService.delete(id);
        }
    
    }

## 负载均衡功能演示 ##

启动eureka-service，两个user-service，feign-service服务，启动后注册中心显示如下：

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly90aGlua3dvbi5ibG9nLmNzZG4ubmV0_size_16_color_FFFFFF_t_70]

多次调用[http://localhost:8701/user/1][http_localhost_8701_user_1]进行测试，可以发现运行在8201和8202的user-service服务交替打印如下信息：

2019-12-27 17:11:57.416  INFO 18096 --- [nio-8202-exec-1] c.j.s.controller.UserController          : 根据id获取用户信息，用户名称为：jourwon
    2019-12-27 17:12:04.897  INFO 18096 --- [nio-8202-exec-2] c.j.s.controller.UserController          : 根据id获取用户信息，用户名称为：jourwon
    2019-12-27 17:12:05.262  INFO 18096 --- [nio-8202-exec-3] c.j.s.controller.UserController          : 根据id获取用户信息，用户名称为：jourwon

## Feign中的服务降级 ##

> Feign中的服务降级使用起来非常方便，只需要为Feign客户端定义的接口添加一个服务降级处理的实现类即可，下面我们为UserService接口添加一个服务降级实现类。

### 添加服务降级实现类UserFallbackService ###

> 需要注意的是它实现了UserService接口，并且对接口中的每个实现方法进行了服务降级逻辑的实现。

@Component
    public class UserFallbackService implements UserService { 
    
        @Override
        public Result insert(User user) { 
            return new Result("调用失败，服务被降级",500);
        }
    
        @Override
        public Result<User> getUser(Long id) { 
            return new Result("调用失败，服务被降级",500);
        }
    
        @Override
        public Result<List<User>> listUsersByIds(List<Long> ids) { 
            return new Result("调用失败，服务被降级",500);
        }
    
        @Override
        public Result<User> getByUsername(String username) { 
            return new Result("调用失败，服务被降级",500);
        }
    
        @Override
        public Result update(User user) { 
            return new Result("调用失败，服务被降级",500);
        }
    
        @Override
        public Result delete(Long id) { 
            return new Result("调用失败，服务被降级",500);
        }
    
    }

### 修改UserService接口，设置服务降级处理类为UserFallbackService ###

> 修改@FeignClient注解中的参数，设置fallback为UserFallbackService.class即可。

@FeignClient(value = "user-service",fallback = UserFallbackService.class)
    public interface UserService { 
    }

### 修改application.yml，开启Hystrix功能 ###

#在Feign中开启Hystrix
    feign:
      hystrix:
        enabled: true

## 服务降级功能演示 ##

关闭两个user-service服务，重新启动feign-service;

调用[http://localhost:8701/user/1][http_localhost_8701_user_1]进行测试，可以发现返回了服务降级信息。

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly90aGlua3dvbi5ibG9nLmNzZG4ubmV0_size_16_color_FFFFFF_t_70 1]

## 日志打印功能 ##

> Feign提供了日志打印功能，我们可以通过配置来调整日志级别，从而了解Feign中Http请求的细节。

### 日志级别 ###

*  NONE：默认的，不显示任何日志；
 *  BASIC：仅记录请求方法、URL、响应状态码及执行时间；
 *  HEADERS：除了BASIC中定义的信息之外，还有请求和响应的头信息；
 *  FULL：除了HEADERS中定义的信息之外，还有请求和响应的正文及元数据。

### 通过配置开启更为详细的日志 ###

> 我们通过java配置来使Feign打印最详细的Http请求日志信息。

@Configuration
    public class FeignConfig { 
    
        @Bean
        Logger.Level level() { 
            return Logger.Level.FULL;
        }
    
    }

### 在application.yml中配置需要开启日志的Feign客户端 ###

> 配置UserService的日志级别为debug。

logging:
      level:
        com.jourwon.springcloud.service: debug

### 查看日志 ###

> 调用[http://localhost:8701/user/1][http_localhost_8701_user_1]进行测试，可以看到以下日志。

2019-12-27 17:16:32.188 DEBUG 18424 --- [-user-service-9] c.j.springcloud.service.UserService      : [UserService#getUser] ---> GET http://user-service/user/1 HTTP/1.1
    2019-12-27 17:16:32.188 DEBUG 18424 --- [-user-service-9] c.j.springcloud.service.UserService      : [UserService#getUser] ---> END HTTP (0-byte body)
    2019-12-27 17:16:32.192 DEBUG 18424 --- [-user-service-9] c.j.springcloud.service.UserService      : [UserService#getUser] <--- HTTP/1.1 200 (3ms)
    2019-12-27 17:16:32.192 DEBUG 18424 --- [-user-service-9] c.j.springcloud.service.UserService      : [UserService#getUser] connection: keep-alive
    2019-12-27 17:16:32.192 DEBUG 18424 --- [-user-service-9] c.j.springcloud.service.UserService      : [UserService#getUser] content-type: application/json
    2019-12-27 17:16:32.192 DEBUG 18424 --- [-user-service-9] c.j.springcloud.service.UserService      : [UserService#getUser] date: Fri, 27 Dec 2019 09:16:32 GMT
    2019-12-27 17:16:32.192 DEBUG 18424 --- [-user-service-9] c.j.springcloud.service.UserService      : [UserService#getUser] keep-alive: timeout=60
    2019-12-27 17:16:32.192 DEBUG 18424 --- [-user-service-9] c.j.springcloud.service.UserService      : [UserService#getUser] transfer-encoding: chunked
    2019-12-27 17:16:32.192 DEBUG 18424 --- [-user-service-9] c.j.springcloud.service.UserService      : [UserService#getUser] 
    2019-12-27 17:16:32.192 DEBUG 18424 --- [-user-service-9] c.j.springcloud.service.UserService      : [UserService#getUser] {"data":{"id":1,"username":"jourwon","password":"123456"},"message":"操作成功","code":200}
    2019-12-27 17:16:32.192 DEBUG 18424 --- [-user-service-9] c.j.springcloud.service.UserService      : [UserService#getUser] <--- END HTTP (94-byte body)

## Feign的常用配置 ##

### Feign自己的配置 ###

feign:
      hystrix:
        enabled: true #在Feign中开启Hystrix
      compression:
        request:
          enabled: false #是否对请求进行GZIP压缩
          mime-types: text/xml,application/xml,application/json #指定压缩的请求数据类型
          min-request-size: 2048 #超过该大小的请求会被压缩
        response:
          enabled: false #是否对响应进行GZIP压缩
    logging:
      level: #修改日志级别
        com.jourwon.springcloud.service: debug

### Feign中的Ribbon配置 ###

在Feign中配置Ribbon可以直接使用Ribbon的配置，具体可以参考[Spring Cloud Netflix Ribbon：服务消费者之服务调用(Hoxton版本)][Spring Cloud Netflix Ribbon_Hoxton]

### Feign中的Hystrix配置 ###

在Feign中配置Hystrix可以直接使用Hystrix的配置，具体可以参考[Spring Cloud Netflix Hystrix：断路器-服务容错保护(Hoxton版本)][Spring Cloud Netflix Hystrix_-_Hoxton]

## 使用到的模块 ##

springcloud-learning
    ├── eureka-server -- eureka注册中心
    ├── user-service -- 提供User对象CRUD接口的服务
    └── feign-service -- feign服务调用测试服务

## 项目源码地址 ##

[GitHub项目源码地址][GitHub]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly90aGlua3dvbi5ibG9nLmNzZG4ubmV0_size_16_color_FFFFFF_t_70]: /images/20210920/6dd47ba655bc4a94bf02bdb00f3512c1.png
[http_localhost_8701_user_1]: http://localhost:8701/user/1
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly90aGlua3dvbi5ibG9nLmNzZG4ubmV0_size_16_color_FFFFFF_t_70 1]: /images/20210920/d124d453ec654b4c98a7ab275dcda126.png
[Spring Cloud Netflix Ribbon_Hoxton]: https://blog.csdn.net/ThinkWon/article/details/103729080
[Spring Cloud Netflix Hystrix_-_Hoxton]: https://blog.csdn.net/ThinkWon/article/details/103732497
[GitHub]: https://github.com/JourWon/springcloud-learning