说明：
1、所谓单机版，就是只是通过URL直接http调用，不依赖ribbon和hystrix，跟微服务不搭嘎。单纯学习下feign，未以后使用微服务做铺垫。
2、主要是学习openFeign自动配置怎么使用和自动配置原理。
3、分析一波配置自动配置httpclient源码
demo
1 依赖：
<!-- spring cloud 依赖 --->
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>Finchley.SR2</version>
<type>pom</type>
<scope>import</scope>
</dependency>
<!--- openfeign 依赖-->
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-openfeign</artifactId>
<version>2.0.2.RELEASE</version>
</dependency>
<!-- feign-httpclient feign整合httpclient依赖依赖-->
<dependency>
<groupId>com.netflix.feign</groupId>
<artifactId>feign-httpclient</artifactId>
<version>8.18.0</version>
</dependency>
2 application.yml 配置
##默认client设置，启用了httpclient配置，client配置超时会被替代
feign.client.config.default.logger-level=full
##feign httpclient配置,连接池配置。
feign.httpclient.enabled=true
feign.httpclient.max-connections=60
feign.httpclient.max-connections-per-route=30
feign.httpclient.connection-timeout=60000
# 配置请求GZIP压缩
feign.compression.request.enabled=true
# 配置响应GZIP压缩
feign.compression.response.enabled=true
#支持压缩的mime types
feign.compression.request.mime-types=text/xml,application/xml,application/json
feign.compression.request.min-request-size=2048
3、代码
/**
* @EnableFeignClients 设置客户端扫描包
* @EnableFeignClients 会扫描所有@FiegnClient注解的接口。
**/
@SpringBootApplication
@EnableFeignClients(basePackages = "com.dayan.client")
public class SpringdemoApplication {
public static void main(String[] args) {
SpringApplication.run(SpringdemoApplication.class, args);
}
}
/**
* 客户端说明
*@FeignClient feign客户端
* 1、url:单机版，用来指定调用服务url
* 2、name：2.0版本必填，单机版没啥用，微服务版本，用来指定注册中心的服务名称。
* springcloudopenfeign，支持了springmvc标签，对openfeign进行了扩展
**/
@FeignClient(url = "${sys.demoUrl}",name = "gitService")
public interface GithubClient {
@RequestMapping(method = RequestMethod.GET, value = "/repos/{owner}/{repo}/contributors")
List<Contributor> contributors(@PathVariable("owner") String owner, @PathVariable("repo") String repo);
}
##以上完事后，直接可以用@Autowire 调用了。
httpclient 自动配置遇到的坑。
官网中对于httpclient支持的介绍,只是and having them on the classpath一句话，没有具体指什么包依赖，这边坑我已经踩了。springcloud openfeign需要依赖feign-httpclient包，而不是httpclient-common就行原因如下:
@Configuration
//apachehttpclient 为 feign-httpclient包里面的类，重点这个包在下面的包中，根本没用，纯属让你用feign-httpclient包？
@ConditionalOnClass(ApacheHttpClient.class)
@ConditionalOnMissingClass("com.netflix.loadbalancer.ILoadBalancer")
@ConditionalOnMissingBean(CloseableHttpClient.class)
@ConditionalOnProperty(value = "feign.httpclient.enabled", matchIfMissing = true)
protected static class HttpClientFeignConfiguration {
private final Timer connectionManagerTimer = new Timer(
"FeignApacheHttpClientConfiguration.connectionManagerTimer", true);
@Autowired(required = false)
private RegistryBuilder registryBuilder;
private CloseableHttpClient httpClient;
//创建httpclientConnectionManange
@Bean
@ConditionalOnMissingBean(HttpClientConnectionManager.class)
public HttpClientConnectionManager connectionManager(
ApacheHttpClientConnectionManagerFactory connectionManagerFactory,
FeignHttpClientProperties httpClientProperties) {
//通过ApacheHttpClientConnectionManagerFactory 创建，底层为PoolingHttpClientConnectionManager独享
final HttpClientConnectionManager connectionManager = connectionManagerFactory
.newConnectionManager(httpClientProperties.isDisableSslValidation(), httpClientProperties.getMaxConnections(),//最大连接数
httpClientProperties.getMaxConnectionsPerRoute(),
httpClientProperties.getTimeToLive(),//存活时间
httpClientProperties.getTimeToLiveUnit(), registryBuilder);
//启动个定时任务，每隔30秒清理失效的连接数。
this.connectionManagerTimer.schedule(new TimerTask() {
@Override
public void run() {
connectionManager.closeExpiredConnections();
}
}, 30000, httpClientProperties.getConnectionTimerRepeat());
return connectionManager;
}
//创建httpclient bean
@Bean
public CloseableHttpClient httpClient(ApacheHttpClientFactory httpClientFactory,
HttpClientConnectionManager httpClientConnectionManager,
FeignHttpClientProperties httpClientProperties) {
//创建RequsetConfig 设置超时时间
RequestConfig defaultRequestConfig = RequestConfig.custom()
.setConnectTimeout(httpClientProperties.getConnectionTimeout())
.setRedirectsEnabled(httpClientProperties.isFollowRedirects())
.build();
//创建httpclient对象。
this.httpClient = httpClientFactory.createBuilder().
setConnectionManager(httpClientConnectionManager).
setDefaultRequestConfig(defaultRequestConfig).build();
return this.httpClient;
}
关于feign，调用自身服务，重复调用问题。
调用代码
@FeignClient(url = "${tuna.url}",name = "tunaClient" ,configuration = TunaClientConfig.class)
@RequestMapping( consumes = MediaType.APPLICATION_JSON_VALUE)
public interface TunaClient {
@RequestMapping(method = RequestMethod.POST, value = "/v1/out/category")
TunaResult book( @RequestHeader(name="sign")String sign,//通用参数 sign
@RequestHeader(name="timeStamp")String timeStamp, //通用参数 timeStamp
@RequestHeader(name="appId")String appId, //通用参数 timeStamp，
@RequestBody BookParam bookParam);
}
接口代码：
@Api(tags = "第三方接口管理")
@RequestMapping(value="/v1/out",produces = MediaType.APPLICATION_JSON_UTF8_VALUE)
public interface ThirdPartyFacade {
@ApiOperation("查询规格")
@RequestMapping(value = "category", method = RequestMethod.POST)
@ResponseBody
ResultMessage category();
如下图所示为判断是否为handler的条件（@Controller 或者@RequsetMapping 注释的类）
1、springmvc 会将@Contoller 或者@RequsetMapping注册到dispatchservlet中。
2、由于feign调用时，requsetMapping注释到接口层（本意设置通用配置），所以被作为handler，注册到了dispatchservlet中。
3、当自己调用自己时，因为feign调用服务申明的路径和接口路径是一致的，而feign的申明也注册到了dispatchservlet中，所以出现了feign调用了自己然后无限调用的情况。、
4、解决办法是，不用在申明feign时，再接口上定义@requsetmapping
@Override
protected boolean isHandler(Class<?> beanType) {
return (AnnotatedElementUtils.hasAnnotation(beanType, Controller.class) ||
AnnotatedElementUtils.hasAnnotation(beanType, RequestMapping.class));
}
