Spring Cloud Feign 概述 了解springcloud架构可以加求求：三五三六二四七二五九

Spring Cloud Feign 基于Netflix Feign 整合了Spring Cloud Ribbon与Spring Cloud Hystrix,还提供了一种声明式的web服务客户端的定义方式,具备可插拔的注解,包括Feign注解和JAX-RS注解,还支持可插拔的HTTP编码器与解码器.

Spring Cloud Feign 搭建

• pom

• <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.cloud</groupId>
      <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
    </dependency>
    <dependency>
      <groupId>org.springframework.cloud</groupId>
      <artifactId>spring-cloud-starter-openfeign</artifactId>
    </dependency>

  Application类上 

• @EnableDiscoveryClient
  @EnableFeignClients  // 开启Feign

  自定义Controller  

• @RestController
  public class ConsumerController {
    @Autowired
    private FeignClient feignClient;
  
    @GetMapping("/{id}")
    public String findById(@PathVariable Long id) {
      return this.feignClient.findById(id);
    }
  }

  基本

  • yml

  • server:
      port: 8010
    spring:
      application:
        name: consumer-service
    eureka:
      client:
        serviceUrl:
          defaultZone: http://localhost:8761/eureka/
      instance:
        prefer-ip-address: true

     单个参数请求

  • 制定Feign接口

  • @FeignClient(name = "provider-service")  //声明需要调用的服务提供者的名称
    public interface FeignClient {
    	
    	 /** 
    	 * 与提供者在Controller定义的一样请求方式和请求路径
         * 通过编写"翻译器"(Contract)，可以让Feign知道第三方注解的含义
         * 同样，SpringCloud也提供了翻译器,会将注解告诉Feign,因此，接口可以直接使用该注解
         * 默认支持注解：@RequestMapping、@RequestParam、@RequestHeader、@PathVariable
         */
        @RequestMapping(value = "/provider/{id}", method = RequestMethod.GET)
        public String findById(@PathVariable("id") Long id);
    }

    多参数请求

    • 自定义Feign接口
      使用Feign构造多参数请求:1.使用post传递对象;2.get在参数列表上分别一个一个,隔开的传输;3.get 传递map

    • @FeignClient(name = "provider-service")
      public interface UserFeignClient {
      
        //该请求不会成功
        @RequestMapping(value = "/provider/get", method = RequestMethod.GET)
        public User get(User user);
      
        @RequestMapping(value = "/provider/get", method = RequestMethod.GET)
        public User get1(@RequestParam("id") Long id, @RequestParam("username") String username);
      
        @RequestMapping(value = "/provider/get", method = RequestMethod.GET)
        public User get2(@RequestParam Map<String, Object> map);
      
        @RequestMapping(value = "/provider/post", method = RequestMethod.POST)
        public User post(@RequestBody User user);
      }

      使用Feign注解

      • yml

      • server:
          port: 8010
        spring:
          application:
            name: consumer-service
        eureka:
          client:
            serviceUrl:
              defaultZone: http://localhost:8761/eureka/
          instance:
            prefer-ip-address: true

        自定义配置类 

      • /**
         * 该类为Feign的配置类
         * 注意：该不应该在主应用程序上下文的@ComponentScan中
         */
        @Configuration
        public class FeignConfiguration {
          /**
           * 将契约改为feign原生的默认契约。这样就可以使用feign自带的注解了。
           * @return 默认的feign契约
           */
          @Bean
          public Contract feignContract() {
            return new feign.Contract.Default();
          }
        }

        制定Feign接口 

      • /**
         * 使用@FeignClient的configuration属性，指定feign的配置类。
         */
        @FeignClient(name = "provider-service",configuration = FeignConfiguration.class)
        public interface FeignClient {
        
          /**
           * 使用feign自带的注解@RequestLine
           */
            @RequestLine("GET /provider/{id}")
            public String findById(@Param("id") Long id);
        
        }

        Feign日志配置

        • 自定义配置类

        • @Configuration
          public class FeignLogConfiguration {
            @Bean
            Logger.Level feignLoggerLevel() {
              return Logger.Level.BASIC;
            }
          }

          制定Feign接口 

        • /**
           * 使用@FeignClient的configuration属性，指定feign的配置类。
           */
          @FeignClient(name = "provider-service",configuration = FeignLogConfiguration.class)
          public interface FeignClient {
          
            /**
             * 使用feign自带的注解@RequestLine
             */
              @RequestMapping(value = "/provider/{id}", method = RequestMethod.GET)
          	public String findById(@PathVariable("id") Long id);
          
          }

          
          

          yml

        • server:
            port: 8010
          spring:
            application:
              name: consumer-service
          eureka:
            client:
              serviceUrl:
                defaultZone: http://localhost:8761/eureka/
            instance:
              prefer-ip-address: true
          logging:
            level:
              com.amor.cloud.feign.FeignClient: DEBUG # 将Feign接口的日志级别设置成DEBUG，因为Feign的Logger.Level只对DEBUG作出响应。

          
          

           Feign压缩配置
          

          feign.compression.request.enabled：设置为true开启请求压缩
          feign.compression.response.enabled：设置为true开启响应压缩
          feign.compression.request.mine-*：数据类型列表，默认为text/xml,application/xml,application/json
          feign.compression.request.min-request-size：设置请求内容的小阀值，默认2048