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
}
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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：
@Configuration
@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;
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();
}
}
}
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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:
<dependency>
<groupId>io.github.openfeign</groupId>
<artifactId>feign-httpclient</artifactId>
<version>9.4.0</version>
</dependency>
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使用OkHttp
查看FeignAutoConfiguration.HttpClientFeignConfiguration的源码：
@Configuration
@ConditionalOnClass({OkHttpClient.class})
@ConditionalOnMissingClass({"com.netflix.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);
}
}
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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：
<dependency>
<groupId>io.github.openfeign</groupId>
<artifactId>feign-okhttp</artifactId>
<version>10.2.0</version>
</dependency>
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OpenFeign替换为OkHttp
pom中引入feign-okhttp
<dependency>
<groupId>io.github.openfeign</groupId>
<artifactId>feign-okhttp</artifactId>
</dependency>
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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
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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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