Feign 使用HttpClient和OkHttp方式

Feign 使用HttpClient和OkHttp方式

目录使用HttpClient和OkHttp使用HttpClient使用OkHttpOpenFeign替换为OkHttppom中引入feign-okhttp在application.yml中配置okhttp

使用HttpClient和OkHttp

在Feign中，Client是一个非常重要的组件，Feign最终发送Request请求以及接收Response响应都是由Client组件来完成的。Client在Feign源码中是一个接口，在默认情况下，Client的实现类是Client.Default。Client.Default是由HttpURLConnection来实现网络请求的。另外,Client还支持HttpClient和OkHttp来进行网络请求。

首先查看FeignRibbonClient的自动配置类FeignRibbonClientAutoConfiguration，该类在程序启动的时候注入一些Bean，其中注入了一个BeanName为feignClient的Client类型的Bean。在省缺配置BeanName为FeignClient的Bean的情况下，会自动注入Client.Default这个对象，跟踪Client.Default源码,Client.Default使用的网络请求框架是HttpURLConnection，代码如下：

public static class Default implements Client {

private final SSLSocketFactory sslContextFactory;

private final HostnameVerifier hostnameVerifier;

public Default(SSLSocketFactory sslContextFactory, HostnameVerifier hostnameVerifier) {

this.sslContextFactory = sslContextFactory;

this.hostnameVerifier = hostnameVerifier;

}

public Response execute(Request request, Options options) throws IOException {

HttpURLConnection connection = this.convertAndSend(request, options);

return this.convertResponse(connection, request);

}

......//代码省略

}

这种情况下，由于缺乏连接池的支持，在达到一定流量的后服务肯定会出问题 。

使用HttpClient

那么如何在Feign中使用HttpClient的框架呢？我们查看FeignAutoConfiguration.HttpClientFeignConfiguration的源码：

@Configuration

@ConditionalOnClass({ApacheHttpClient.class})

@ConditionalOnMissingClass({"com-flix.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;

protected HttpClientFeignConfiguration() {

}

@Bean

@ConditionalOnMissingBean({HttpClientConnectionManager.class})

public HttpClientConnectionManager connectionManager(ApacheHttpClientConnectionManagerFactory connectionManagerFactory, FeignHttpClientProperties httpClientProperties) {

final HttpClientConnectionManager connectionManager = connectionManagerFactory.newConnectionManager(httpClientProperties.isDisableSslValidation(), httpClientProperties.getMaxConnections(), httpClientProperties.getMaxConnectionsPerRoute(), httpClientProperties.getTimeToLive(), httpClientProperties.getTimeToLiveUnit(), this.registryBuilder);

this.connectionManagerTimer.schedule(new TimerTask() {

public void run() {

connectionManager.closeExpiredConnections();

}

}, 30000L, (long)httpClientProperties.getConnectionTimerRepeat());

return connectionManager;

}

@Bean

public CloseableHttpClient httpClient(ApacheHttpClientFactory httpClientFactory, HttpClientConnectionManager httpClientConnectionManager, FeignHttpClientProperties httpClientProperties) {

RequestConfig defaultRequestConfig = RequestConfig.custom().setConnectTimeout(httpClientProperties.getConnectionTimeout()).setRedirectsEnabled(httpClientProperties.isFollowRedirects()).build();

this.httpClient = httpClientFactory.createBuilder().setConnectionManager(httpClientConnectionManager).setDefaultRequestConfig(defaultRequestConfig).build();

return this.httpClient;

}

@Bean

@ConditionalOnMissingBean({Client.class})

public Client feignClient(HttpClient httpClient) {

return new ApacheHttpClient(httpClient);

}

@PreDestroy

public void destroy() throws Exception {

this.connectionManagerTimer.cancel();

if (this.httpClient != null) {

this.httpClient.close();

}

}

}

从代码@ConditionalOnClass({ApacheHttpClient.class})注解可知，只需要在pom文件上加上HttpClient依赖即可。另外需要在配置文件中配置feign.httpclient.enabled为true，从@ConditionalOnProperty注解可知，这个配置可以不写，因为在默认情况下就为true:

io.github.openfeign

feign-httpclient

9.4.0

使用OkHttp

查看FeignAutoConfiguration.HttpClientFeignConfiguration的源码：

@Configuration

@ConditionalOnClass({OkHttpClient.class})

@ConditionalOnMissingClass({"com-flix.loadbalancer.ILoadBalancer"})

@ConditionalOnMissingBean({okhttp3.OkHttpClient.class})

@ConditionalOnProperty({"feign.okhttp.enabled"})

protected static class OkHttpFeignConfiguration {

private okhttp3.OkHttpClient okHttpClient;

protected OkHttpFeignConfiguration() {

}

@Bean

@ConditionalOnMissingBean({ConnectionPool.class})

public ConnectionPool httpClientConnectionPool(FeignHttpClientProperties httpClientProperties, OkHttpClientConnectionPoolFactory connectionPoolFactory) {

Integer maxTotalConnections = httpClientProperties.getMaxConnections();

Long timeToLive = httpClientProperties.getTimeToLive();

TimeUnit ttlUnit = httpClientProperties.getTimeToLiveUnit();

return connectionPoolFactory.create(maxTotalConnections, timeToLive, ttlUnit);

}

@Bean

public okhttp3.OkHttpClient client(OkHttpClientFactory httpClientFactory, ConnectionPool connectionPool, FeignHttpClientProperties httpClientProperties) {

Boolean followRedirects = httpClientProperties.isFollowRedirects();

Integer connectTimeout = httpClientProperties.getConnectionTimeout();

Boolean disableSslValidation = httpClientProperties.isDisableSslValidation();

this.okHttpClient = httpClientFactory.createBuilder(disableSslValidation).connectTimeout((long)connectTimeout, TimeUnit.MILLISECONDS).followRedirects(followRedirects).connectionPool(connectionPool).build();

return this.okHttpClient;

}

@PreDestroy

public void destroy() {

if (this.okHttpClient != null) {

this.okHttpClient.dispatcher().executorService().shutdown();

this.okHttpClient.connectionPool().evictAll();

}

}

@Bean

@ConditionalOnMissingBean({Client.class})

public Client feignClient(okhttp3.OkHttpClient client) {

return new OkHttpClient(client);

}

}

同理，如果想要在Feign中使用OkHttp作为网络请求框架，则只需要在pom文件中加上feign-okhttp的依赖，代码如下：

io.github.openfeign

feign-okhttp

10.2.0

OpenFeign替换为OkHttp

pom中引入feign-okhttp

io.github.openfeign

feign-okhttp

在application.yml中配置okhttp

feign:

httpclient:

connection-timeout: 2000 #单位ms,默认2000

max-connections: 200 #线程池最大连接数

okhttp:

enabled: true

经过上面设置已经可以使用okhttp了，因为在FeignAutoConfiguration中已实现自动装配

如果需要对okhttp做更精细的参数设置，那需要自定义okhttp的实现，可以模仿上图中的实现

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