Question

无法让Feign客户端工作。首先尝试使用POST。保持运行与编码器/解码器相关的错误说类型不正确。然后在github上找到一个例子，最后调用简单的GET API并决定试一试。仍然失败

在Github和网上，我看到了Feign Client的多个版本 Spring-Cloud，OpenFign，Netflix.feign有不同的版本。任何人都可以描述一下应该用于生产的最好和最稳定的Feign客户端吗？

package com.paa.controllers;

import org.springframework.cloud.netflix.feign.FeignClient;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

@FeignClient (name="test-service",url="https://www.reddit.com/r")
public interface GetFeignClient {

     @RequestMapping(method = RequestMethod.GET, value = "/java.json")
     public String posts();
}

Controller:

@RestController
@RequestMapping("/some/api")
public class TestWLCController {

  @Autowired
  private GetFeignClient getFeignClient;

  .. some stuff


    @RequestMapping(value="/postSomething",method = RequestMethod.POST)
    @ApiOperation(value = "Configures something",
            notes = "basic rest controller for testing feign")

    public ResponseEntity<SomeResponse> feignPost(
            UriComponentsBuilder builder,
            @ApiParam(name = "myRequest", 
            value = "request for configuring something", 
            required = true)
            @Valid @RequestBody SomeRequest someRequest) {

        String resp = null;
        try {
            resp = getFeignClient.posts();
        } catch (Exception er) {
            er.printStackTrace();
        }

    }
}

应用：

尝试了所有可能的注释排列，认为它会解决AutoWire的问题，但仍然失败

@Configuration
@ComponentScan
@EnableAutoConfiguration
//@EnableEurekaClient
@EnableFeignClients

//@SpringBootApplication
//@EnableFeignClients
//@EnableFeignClients(basePackages = {"com.paa.xenia.controllers", "com.paa.xenia.services"})
public class ServiceApplication extends SpringBootServletInitializer {

    @Override
    protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {

        return application.sources(XeniaServiceApplication.class);
    }

    public static void main(String[] args) {

        SpringApplication.run(ServiceApplication.class, args);
    }
}

2016-07-20 18：15：42.406 [0; 39m [31mERROR [0; 39m [35m32749 [0; 39m]   [2m --- [0; 39m [2m [主] [0; 39m   [36mo.s.boot.SpringApplication [0; 39m [2m：[0; 39m   应用程序启动失败

org.springframework.beans.factory.BeanCreationException：错误   创建名为＆＃39; testWLCController＆＃39;：注入自动装配的bean   依赖失败;嵌套异常是   org.springframework.beans.factory.BeanCreationException：不能   autowire字段：private com.paa.controllers.GetFeignClient   com.paa.controllers.TestWLCController.gfClient;嵌套异常是   org.springframework.beans.factory.BeanCreationException：错误   创建名为＆＃39; com.aa..controllers.GetFeignClient＆＃39;的bean   FactoryBean在对象创建时抛出异常;嵌套异常是   java.lang.NullPointerException at   org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues（AutowiredAnnotationBeanPostProcessor.java:334）   〜[spring-beans-4.2.6.RELEASE.jar：4.2.6.RELEASE] at   org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean（AbstractAutowireCapableBeanFactory.java:1214）   〜[spring-beans-4.2.6.RELEASE.jar：4.2.6.RELEASE] at   org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean（AbstractAutowireCapableBeanFactory.java:543）   〜[spring-beans-4.2.6.RELEASE.jar：4.2.6.RELEASE] at   org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean（AbstractAutowireCapableBeanFactory.java:482）   〜[spring-beans-4.2.6.RELEASE.jar：4.2.6.RELEASE] at   org.springframework.beans.factory.support.AbstractBeanFactory $ 1.getObject（AbstractBeanFactory.java:306）   〜[spring-beans-4.2.6.RELEASE.jar：4.2.6.RELEASE] at   org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton（DefaultSingletonBeanRegistry.java:230）   〜[spring-beans-4.2.6.RELEASE.jar：4.2.6.RELEASE] at   org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean（AbstractBeanFactory.java:302）   〜[spring-beans-4.2.6.RELEASE.jar：4.2.6.RELEASE] at   org.springframework.beans.factory.support.AbstractBeanFactory.getBean（AbstractBeanFactory.java:197）   〜[spring-beans-4.2.6.RELEASE.jar：4.2.6.RELEASE] at   org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons（DefaultListableBeanFactory.java:772）   〜[spring-beans-4.2.6.RELEASE.jar：4.2.6.RELEASE] at   org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization（AbstractApplicationContext.java:839）   〜[spring-context-4.2.6.RELEASE.jar：4.2.6.RELEASE] at   org.springframework.context.support.AbstractApplicationContext.refresh（AbstractApplicationContext.java:538）   〜[spring-context-4.2.6.RELEASE.jar：4.2.6.RELEASE] at   org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh（EmbeddedWebApplicationContext.java:118）   〜[spring-boot-1.3.5.RELEASE.jar：1.3.5.RELEASE] at   org.springframework.boot.SpringApplication.refresh（SpringApplication.java:766）   [spring-boot-1.3.5.RELEASE.jar：1.3.5.RELEASE] at   org.springframework.boot.SpringApplication.createAndRefreshContext（SpringApplication.java:361）   [spring-boot-1.3.5.RELEASE.jar：1.3.5.RELEASE] at   org.springframework.boot.SpringApplication.run（SpringApplication.java:307）   [spring-boot-1.3.5.RELEASE.jar：1.3.5.RELEASE] at   org.springframework.boot.SpringApplication.run（SpringApplication.java:1191）   [spring-boot-1.3.5.RELEASE.jar：1.3.5.RELEASE] at   org.springframework.boot.SpringApplication.run（SpringApplication.java:1180）   [spring-boot-1.3.5.RELEASE.jar：1.3.5.RELEASE] at   com.paa.ServiceApplication.main（ServiceApplication.java:44）[bin /：na]   引起：org.springframework.beans.factory.BeanCreationException：   无法自动装配字段：private com.paa.controllers.GetFeignClient   com.paa.controllers.TestWLCController.gfClient;嵌套异常是   org.springframework.beans.factory.BeanCreationException：错误   创建名为＆＃39; com.paa.controllers.GetFeignClient＆＃39;的bean   FactoryBean在对象创建时抛出异常;嵌套异常是   java.lang.NullPointerException at   org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor $ AutowiredFieldElement.inject（AutowiredAnnotationBeanPostProcessor.java:573）   〜[spring-beans-4.2.6.RELEASE.jar：4.2.6.RELEASE] at   org.springframework.beans.factory.annotation.InjectionMetadata.inject（InjectionMetadata.java:88）   〜[spring-beans-4.2.6.RELEASE.jar：4.2.6.RELEASE] at   org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues（AutowiredAnnotationBeanPostProcessor.java:331）   〜[spring-beans-4.2.6.RELEASE.jar：4.2.6.RELEASE] ... 17 com.n frames   省略

Answer 1

我不确定你是否最终自己弄清楚了，但是为了其他可能偶然发现这个问题的人，下面是你要做的事情的一个有效例子。我首先要指出一些不正确的，或者至少在代码中不需要的东西，然后展示我的代码。

您应该尽量不使用url属性。而是使用<feign client name>.ribbon.listOfServers（或bootstrap.yml）中的bootstrap.properties设置服务器列表。这允许客户端负载平衡，因为listOfServers可以是以逗号分隔的列表。
使用功能区进行HTTPS连接，您需要指定HTTP连接不需要的两件事。该端口是listOfServers和<feign client name>.ribbon.IsSecure: true的一部分。如果没有端口，则连接到端口80，如果没有IsSecure，则使用HTTP。

使用curl进行测试，我发现Reddit需要非常很长时间才能做出响应。有关如何细分请求 - 响应周期所花费的总时间的详细信息，请参阅此SO post。

$ curl -v -H "User-Agent: Mozilla/5.0" -w "@curl-format.txt" -o /dev/null -s "https://www.reddit.com/r/java/top.json?count=1"
{ [2759 bytes data]
* Connection #0 to host www.reddit.com left intact
time_namelookup:     0.527
time_connect:        0.577
time_appconnect:     0.758
time_pretransfer:    0.758
time_redirect:       0.000
time_starttransfer: 11.189
                  ----------
time_total:         11.218

根据Netflix Wiki，默认的读取和连接超时为3000毫秒，因此除非您更改，否则您将始终超时。

您可能已经注意到我在User-Agent请求中指定了curl标头。这是因为Reddis似乎对此非常挑剔，如果没有指定，则返回HTTP 429＆＃34;太多的请求＆＃34;大部分的时间。他们不会在回复中返回Retry-After标题，因此在发出其他请求之前，您无需等待多长时间。
Spring Cloud Netflix以及Netflix Feign是开源的，因此一些（很多）耐心和调试技巧非常方便。

＆＃34;谈话很便宜。告诉我代码。＆＃34; （Torvalds，Linus（2000-08-25））。

我使用优秀的Spring Initializr网站制作了Gradle应用。这是build.gradle文件的摘录。

dependencies {
    compile('org.springframework.cloud:spring-cloud-starter-feign')
    compile('org.springframework.boot:spring-boot-starter-web')
    testCompile('org.springframework.boot:spring-boot-starter-test')
}

dependencyManagement {
    imports {
        mavenBom "org.springframework.cloud:spring-cloud-dependencies:Camden.SR3"
    }
}

怀抱客户：

@FeignClient(name = "reddit")
public interface RedditClient {
    @RequestMapping(method = GET, value = "/r/java/top.json?count=1",
            headers = {USER_AGENT + "=Mozilla/5.0", ACCEPT + "=" + APPLICATION_JSON_VALUE})
    public String posts();
}

启动应用：

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

    @RestController
    static class DemoController {
        @Autowired
        private RedditClient redditClient;

        @GetMapping("/posts")
        public String posts() {
            return redditClient.posts();
        }
    }
}

<强> bootstrap.yml ：

reddit:
  ribbon:
    listOfServers: www.reddit.com:443
    ConnectTimeout: 20000
    ReadTimeout: 20000
    IsSecure: true
hystrix.command.default.execution:
  timeout.enabled: true
  isolation.thread.timeoutInMilliseconds: 50000

整合测试：

@RunWith(SpringRunner.class)
@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
public class DemoApplicationTest {
    @Autowired
    private TestRestTemplate restTemplate;

    @Test
    public void testGetPosts() {
        ResponseEntity<String> responseEntity = restTemplate.getForEntity("/posts", String.class);

        HttpStatus statusCode = responseEntity.getStatusCode();
        assertThat(String.format("Actual status code: %d, reason: %s.",
                statusCode.value(), statusCode.getReasonPhrase()),
                statusCode.is2xxSuccessful(), equalTo(true));
    }
}

Answer 2

依赖项：

<dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-ribbon</artifactId>
        </dependency>

         <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-parent</artifactId>
                <version>Greenwich.RELEASE</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

应用程序：

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.openfeign.EnableFeignClients;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

import com.test.cloud.bookservice.models.Book;

@SpringBootApplication
@RestController
@RequestMapping("/books")
@EnableFeignClients
public class BookServiceApplication {

    Logger logger = LogManager.getLogger(BookServiceApplication.class);

    @Autowired
    private StoreClient storeClient;


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


    @GetMapping("/book")
    public Book findBook() {
            return this.restTemplate.getForObject("http://stores/book", Book.class);
    }

    @FeignClient(name = "StoreClient", url = "127.0.0.1:8089")
    interface StoreClient {
        @RequestMapping(method = RequestMethod.GET, value = "/stores/book", consumes = "application/json")
        Book getBook();
    }

}

无法让Feign客户端为基本示例

2 个答案: