Feign

安装

在 Maven 工程中使用

  <dependency>
        <groupId>com.zhengcheng</groupId>
        <artifactId>zc-feign-spring-boot-starter</artifactId>
  </dependency>

属性配置

# 启用 okhttp3 的属性配置
feign.httpclient.enabled = false
feign.okhttp.enabled = true
feign.okhttp3.read-timeout = 3000
feign.okhttp3.connect-timeout = 5000
feign.okhttp3.write-timeout = 60000

# hystrix 配置
hystrix.command.default.execution.timeout.enabled = true
hystrix.command.default.execution.isolation.thread.timeoutInMilliseconds = 10000
hystrix.threadpool.default.coreSize=100
hystrix.threadpool.default.maxQueueSize=1000

# spring cloud 下 ribbon 的配置
ribbon.connect-timeout = 3000
ribbon.read-timeout = 5000
 
# sso 是 feign 的 name
hystrix.threadpool.sso.coreSize=10
hystrix.threadpool.sso.maxQueueSize=100
hystrix.command.sso.execution.isolation.thread.timeoutInMilliseconds=3000

更多设置请参考[Feign官方文档]

• 推荐设置 feign.hystrix.enabled = true , 打开Feign的熔断
• 自动配置修改了Feign的日志输出为INFO级别
• 增加了开启hystrix以后，对Feign的分布式链路日志追踪的配置

要求Feign接口的包路径满足以下条件（否则不能自动扫描到FeignClient）：

@EnableFeignClients("com.zhengcheng.**.feign.**")

最佳实践

特别说明

feign 的请求使用SpringMvc的注解，并且要求必须有回退且使用工厂模式

FeignClient

@FeignClient(name = "MARRY", fallbackFactory = MarryFeignClientFallbackFactory.class)
public interface MarryFeignClient {

    @GetMapping("/activities/match")
    Result<List<Long>> match();

    @GetMapping("/activities/match/{id}")
    Result<List<Long>> match(@PathVariable("id") Long id);
}

FallbackFactory

@Slf4j
@Component
public class MarryFeignClientFallbackFactory implements FallbackFactory<MarryFeignClient> {
    @Override
    public MarryFeignClient create(Throwable throwable) {
        return new MarryFeignClient() {
            @Override
            public Result<List<Long>> match() {
                log.error("match,fallback;reason was:{}", throwable.getMessage(), throwable);
                return Result.fallbackResult();
            }

            @Override
            public Result<List<Long>> match(Long id) {
                log.error("match,fallback;reason was:{}", throwable.getMessage(), throwable);
                return Result.fallbackResult();
            }
        };
    }
}

注意

禁止使用原生Feign注解调用feign接口

    @RequestLine(value = "GET /activities/match")
    Result<List<Long>> match();

注意

禁止使用非工厂模式的fallback

@FeignClient(name = "MARRY", fallbackFactory = MarryFeignClientFallback.class)

Feign @QueryMap support

OpenFeign的@QueryMap注解支持将POJO用作GET参数映射。但是，默认的OpenFeign的QueryMap注解与Spring不兼容，因为它缺少value属性。

Spring Cloud OpenFeign 提供了等效的@SpringQueryMap注解，用于注释POJO或Map参数作为查询参数映射。

例如，Params该类定义参数param1和param2：

// Params.java
public class Params {
    private String param1;
    private String param2;

    // [Getters and setters omitted for brevity]
}

以下Feign客户端Params通过使用@SpringQueryMap注解使用该类：

@FeignClient("demo")
public interface DemoTemplate {

    @GetMapping(path = "/demo")
    String demoEndpoint(@SpringQueryMap Params params);
}

如果需要对生成的查询参数映射进行更多控制，则可以实现一个自定义QueryMapEncoder bean。

Feign OAuth2

在使用 spring-security-oauth2 的情况下，服务之间传递当前登录用户信息需要手动配置 Feign OAuth2 拦截器

public class FeignInterceptorConfig {

    /**
     * 使用feign client访问别的微服务时，将access_token放入参数或者header ，Authorization:Bearer xxx
     * 或者url?access_token=xxx
     */
    @Bean
    public RequestInterceptor requestInterceptor() {
        RequestInterceptor requestInterceptor = template -> {
            Authentication authentication = SecurityContextHolder.getContext().getAuthentication();
            if (authentication != null) {
                if (authentication instanceof OAuth2Authentication) {
                    OAuth2AuthenticationDetails details = (OAuth2AuthenticationDetails) authentication.getDetails();
                    template.header("Authorization", OAuth2AccessToken.BEARER_TYPE + " " + details.getTokenValue());
                    template.header(FeignAutoConfiguration.REQUEST_ID, IdUtil.fastSimpleUUID());
                }
            }
        };
        return requestInterceptor;
    }
}