Feign-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：
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public
static
class Default implements Client {
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private
final SSLSocketFactory sslContextFactory;
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private
final HostnameVerifier hostnameVerifier;
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public Default(SSLSocketFactory sslContextFactory, HostnameVerifier hostnameVerifier) {
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this.sslContextFactory = sslContextFactory;
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this.hostnameVerifier = hostnameVerifier;
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}
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public Response execute(Request request, Options options) throws IOException {
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HttpURLConnection connection =
this.convertAndSend(request, options);
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return
this.convertResponse(connection, request);
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}
-
-
......
//代码省略
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}
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：
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@Configuration
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@ConditionalOnClass({ApacheHttpClient.class})
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@ConditionalOnMissingClass({"com.netflix.loadbalancer.ILoadBalancer"})
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@ConditionalOnMissingBean({CloseableHttpClient.class})
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@ConditionalOnProperty(
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value = {"feign.httpclient.enabled"},
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matchIfMissing = true
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)
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protected static
class HttpClientFeignConfiguration {
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private
final Timer connectionManagerTimer = new Timer(
"FeignApacheHttpClientConfiguration.connectionManagerTimer",
true);
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@Autowired(
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required = false
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)
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private RegistryBuilder registryBuilder;
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private CloseableHttpClient httpClient;
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protected HttpClientFeignConfiguration() {
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}
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@Bean
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@ConditionalOnMissingBean({HttpClientConnectionManager.class})
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public HttpClientConnectionManager connectionManager(ApacheHttpClientConnectionManagerFactory connectionManagerFactory, FeignHttpClientProperties httpClientProperties) {
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final HttpClientConnectionManager connectionManager = connectionManagerFactory.newConnectionManager(httpClientProperties.isDisableSslValidation(), httpClientProperties.getMaxConnections(), httpClientProperties.getMaxConnectionsPerRoute(), httpClientProperties.getTimeToLive(), httpClientProperties.getTimeToLiveUnit(),
this.registryBuilder);
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this.connectionManagerTimer.schedule(new TimerTask() {
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public void run() {
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connectionManager.closeExpiredConnections();
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}
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},
30000L, (long)httpClientProperties.getConnectionTimerRepeat());
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return connectionManager;
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}
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@Bean
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public CloseableHttpClient httpClient(ApacheHttpClientFactory httpClientFactory, HttpClientConnectionManager httpClientConnectionManager, FeignHttpClientProperties httpClientProperties) {
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RequestConfig defaultRequestConfig = RequestConfig.custom().setConnectTimeout(httpClientProperties.getConnectionTimeout()).setRedirectsEnabled(httpClientProperties.isFollowRedirects()).build();
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this.httpClient = httpClientFactory.createBuilder().setConnectionManager(httpClientConnectionManager).setDefaultRequestConfig(defaultRequestConfig).build();
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return
this.httpClient;
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}
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@Bean
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@ConditionalOnMissingBean({Client.class})
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public Client feignClient(HttpClient httpClient) {
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return new ApacheHttpClient(httpClient);
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}
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@PreDestroy
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public void destroy() throws Exception {
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this.connectionManagerTimer.cancel();
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if (
this.httpClient !=
null) {
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this.httpClient.close();
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}
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}
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}
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:
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<dependency>
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<groupId>io.github.openfeign
groupId>
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<artifactId>feign-httpclient
artifactId>
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<version>9.4.0
version>
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dependency>
使用OkHttp
查看FeignAutoConfiguration.HttpClientFeignConfiguration的源码：
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@Configuration
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@ConditionalOnClass({OkHttpClient.class})
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@ConditionalOnMissingClass({"com.netflix.loadbalancer.ILoadBalancer"})
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@ConditionalOnMissingBean({okhttp3.OkHttpClient.class})
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@ConditionalOnProperty({"feign.okhttp.enabled"})
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protected static
class OkHttpFeignConfiguration {
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private okhttp3.OkHttpClient okHttpClient;
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protected OkHttpFeignConfiguration() {
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}
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@Bean
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@ConditionalOnMissingBean({ConnectionPool.class})
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public ConnectionPool httpClientConnectionPool(FeignHttpClientProperties httpClientProperties, OkHttpClientConnectionPoolFactory connectionPoolFactory) {
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Integer maxTotalConnections = httpClientProperties.getMaxConnections();
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Long timeToLive = httpClientProperties.getTimeToLive();
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TimeUnit ttlUnit = httpClientProperties.getTimeToLiveUnit();
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return connectionPoolFactory.create(maxTotalConnections, timeToLive, ttlUnit);
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}
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@Bean
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public okhttp3.OkHttpClient client(OkHttpClientFactory httpClientFactory, ConnectionPool connectionPool, FeignHttpClientProperties httpClientProperties) {
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Boolean followRedirects = httpClientProperties.isFollowRedirects();
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Integer connectTimeout = httpClientProperties.getConnectionTimeout();
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Boolean disableSslValidation = httpClientProperties.isDisableSslValidation();
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this.okHttpClient = httpClientFactory.createBuilder(disableSslValidation).connectTimeout((long)connectTimeout, TimeUnit.MILLISECONDS).followRedirects(followRedirects).connectionPool(connectionPool).build();
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return
this.okHttpClient;
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}
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@PreDestroy
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public void destroy() {
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if (
this.okHttpClient !=
null) {
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this.okHttpClient.dispatcher().executorService().shutdown();
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this.okHttpClient.connectionPool().evictAll();
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}
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}
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@Bean
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@ConditionalOnMissingBean({Client.class})
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public Client feignClient(okhttp3.OkHttpClient client) {
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return new OkHttpClient(client);
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}
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}
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：
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<dependency>
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<groupId>io.github.openfeign
groupId>
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<artifactId>feign-okhttp
artifactId>
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<version>10.2.0
version>
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dependency>