项目中使用了 feign 作为 http 请求工具 . feign 自带的 http 客户端是 HttpURLConnection , 没有连接池功能 , 可配置能力差 , 因此通常会使用更强大的 OkHttp 作为底层的客户端实现 , 然后很多时候会发现对于 OkHttp 的自定义配置均会失效 , 这里记录下解决方案

先演示下通常是怎么配置的, 首先引入依赖

1
2
3
4
5
<dependency>
     <groupId>io.github.openfeign</groupId>
     <artifactId>feign-core</artifactId>
     <version>11.8</version>
 </dependency>

再修改Feign配置类

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
@Configuration
@ConditionalOnClass(Feign.class)
@AutoConfigureBefore(FeignAutoConfiguration.class)
public class FeignConfig {
    // 注入feignContract
    @Bean
    public Contract feignContract() {
        return new feign.Contract.Default();
    }

    // 注入自定义的okHttpClient
    @Bean
    public okhttp3.OkHttpClient okHttpClient(){
        return new okhttp3.OkHttpClient.Builder()
            .readTimeout(60, TimeUnit.SECONDS)
            .connectTimeout(60, TimeUnit.SECONDS) 
            .writeTimeout(120, TimeUnit.SECONDS) 
            .connectionPool(new ConnectionPool())
            .build();
    }
}

然后开启 OkHttp 作为 Feign 客户端

1
2
3
4
# application.yml
feign:
    okhttp:
        enabled: true

到这里通常就结束了, 网上许多文章也是如此说明 , 可是当实际需求来时 , 比如请求时增加一个通用 header ,在给这个注入的 Okhttp 增加拦截器时发现实际请求并未生效.

定位问题

可以将服务根日志级别调整为 debug , 然后按照 [文章](真实案例：Feign切换client到okhttp无法生效，被老大骂得有点慌 - 简书) 进行调试 ,

会发现 OkHttp 的配置不符合运行条件 , 因此实际使用的还是默认配置

继续查看 FeignAutoConfiguration 这个配置类的细节

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
@Configuration
@ConditionalOnClass({Feign.class})
@EnableConfigurationProperties({FeignClientProperties.class, FeignHttpClientProperties.class})
public class FeignAutoConfiguration {
    // .....其他的配置
    @Configuration
    @ConditionalOnClass({OkHttpClient.class})
    @ConditionalOnMissingClass({"com.netflix.loadbalancer.ILoadBalancer"})
    @ConditionalOnMissingBean({okhttp3.OkHttpClient.class})
    @ConditionalOnProperty({"feign.okhttp.enabled"})
    protected static class OkHttpFeignConfiguration {
       // ...okhttp的配置
    }

    // .....其他的配置
}

问题就出在这里 @ConditionalOnMissingBean({okhttp3.OkHttpClient.class})

即只有当容器中没有OkHttpClient的实例时 , 才会运行 . 而我们需要的就是注入了自定义 OkHttp , 因此只能自己实现

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
@Configuration
@ConditionalOnClass(Feign.class)
@AutoConfigureAfter(FeignAutoConfiguration.class)
public class OkHttpFeignConfiguration {

    @Bean
    @ConditionalOnMissingBean({Client.class})
    public Client feignClient(okhttp3.OkHttpClient client) {
        return new feign.okhttp.OkHttpClient(client);
    }

    @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 OkHttpClient client(OkHttpClientFactory httpClientFactory, ConnectionPool connectionPool, FeignHttpClientProperties httpClientProperties) {
        return new OkHttpClient.Builder()
                .connectTimeout(8, TimeUnit.SECONDS)
                .readTimeout(8,TimeUnit.SECONDS)
                .writeTimeout(12,TimeUnit.SECONDS)
                .addInterceptor(new HeaderInterceptor())
                .sslSocketFactory(SSLSocketClient.getSSLSocketFactory(), new TrustAllManager())
                .hostnameVerifier(SSLSocketClient.getHostnameVerifier())
                .build();
    }
}

当实际运行时 , 我们会发现已经生效 .