使用Apache HttpComponents为Webflux WebClient配置SSL出现类转换异常

问题原因 #

你使用的PoolingHttpClientConnectionManager是Apache HttpClient5中用于同步阻塞IO场景的连接管理器，归属org.apache.hc.client5.http.impl.io包；而WebClient依赖的是异步非阻塞的HttpAsyncClient，要求连接管理器必须实现org.apache.hc.client5.http.nio.AsyncClientConnectionManager接口，二者类型不匹配，因此强转抛出异常。

解决方案 #

替换为异步场景专用的连接管理器PoolingAsyncClientConnectionManager，同时适配异步SSL连接工厂配置，修正后的代码如下：

private ClientHttpConnector buildClientConnector() {
    HttpAsyncClientBuilder clientBuilder = HttpAsyncClients.custom();
    org.apache.hc.core5.http.HttpHost proxy = new org.apache.hc.core5.http.HttpHost(proxyHost, proxyPort);
    org.apache.hc.client5.http.auth.CredentialsProvider credsProvider = new org.apache.hc.client5.http.impl.auth.BasicCredentialsProvider();
    ((org.apache.hc.client5.http.impl.auth.BasicCredentialsProvider) credsProvider).setCredentials(new org.apache.hc.client5.http.auth.AuthScope(proxyHost, proxyPort),
            new org.apache.hc.client5.http.auth.UsernamePasswordCredentials(proxyUser, proxyPassword.toCharArray()));
    clientBuilder.useSystemProperties();
    clientBuilder.setProxy(proxy);
    clientBuilder.setDefaultCredentialsProvider(credsProvider);
    clientBuilder.setProxyAuthenticationStrategy(new DefaultAuthenticationStrategy());

    TrustStrategy acceptingTrustStrategy = (x509Certificates, s) -> true;

    SSLContext sslContext = null;
    try {
        sslContext = org.apache.http.ssl.SSLContexts.custom().loadTrustMaterial(null, acceptingTrustStrategy).build();
    } catch (KeyManagementException | NoSuchAlgorithmException | KeyStoreException e) {
        throw new ServiceException(GlobalErrorMessage.INTERNAL_SERVER_ERROR);
    }

    // 异步场景使用SSLConnectionSocketFactory配置TLS参数
    org.apache.hc.client5.http.ssl.SSLConnectionSocketFactory sslSocketFactory =
            new org.apache.hc.client5.http.ssl.SSLConnectionSocketFactory(sslContext, new NoopHostnameVerifier());

    // 构造异步连接管理器
    PoolingAsyncClientConnectionManager connectionManager = PoolingAsyncClientConnectionManagerBuilder.create()
            .setSSLSocketFactory(sslSocketFactory)
            .build();

    CloseableHttpAsyncClient client = clientBuilder
            .setConnectionManager(connectionManager)
            .setRoutePlanner(new org.apache.hc.client5.http.impl.routing.DefaultProxyRoutePlanner(proxy) {
                @Override
                protected org.apache.hc.core5.http.HttpHost determineProxy(org.apache.hc.core5.http.HttpHost target, org.apache.hc.core5.http.protocol.HttpContext context) throws org.apache.hc.core5.http.HttpException {
                    if (target.getHostName().equals(noproxy)) {
                        return null;
                    }
                    return super.determineProxy(target, context);
                }
            })
            .build();
    client.start(); // 异步客户端需要手动启动
    ClientHttpConnector connector = new HttpComponentsClientHttpConnector(client);
    return connector;
}

额外注意点 #

• 异步HttpAsyncClient构造完成后必须调用start()方法启动，否则会抛出客户端未运行的异常
• 无需手动强转连接管理器类型，PoolingAsyncClientConnectionManager本身已经实现了AsyncClientConnectionManager接口

内容的提问来源于stack exchange，提问作者Amir Choubani