OkHttpClient自签名证书

Question

需要将android应用（改进的REST API）与具有自签名证书的服务器连接，因此我必须信任此证书。

我必须使用：file_certificate.crt，file_chain.chain和file_key.key

在linux中，我运行以下命令：

openssl s_client -connect my.host.com:443 -state -tls1_2 -key file_key.key -cert file_certificate.crt -CAfile file_chain.chain

并且连接成功完成... Verify return code: 0 (ok)

那么如何创建OkHttpClient来使用这3个文件，因为我发现的是使用单个CA文件，如下所示：

 public static OkHttpClient createClient(Context context) {

    OkHttpClient client = null;

    CertificateFactory cf = null;
    InputStream cert = null;
    Certificate ca = null;
    SSLContext sslContext = null;
    try {
        cf = CertificateFactory.getInstance("X.509");
        cert = context.getResources().openRawResource(R.raw.file_certificate); // Place your 'my_cert.crt' file in `res/raw`

        ca = cf.generateCertificate(cert);
        cert.close();

        String keyStoreType = KeyStore.getDefaultType();
        KeyStore keyStore = KeyStore.getInstance(keyStoreType);
        keyStore.load(null, null);
        keyStore.setCertificateEntry("ca", ca);

        String tmfAlgorithm = TrustManagerFactory.getDefaultAlgorithm();
        TrustManagerFactory tmf = TrustManagerFactory.getInstance(tmfAlgorithm);
        tmf.init(keyStore);

        sslContext = SSLContext.getInstance("TLS");
        sslContext.init(null, tmf.getTrustManagers(), null);

        client = new OkHttpClient.Builder()
                .sslSocketFactory(sslContext.getSocketFactory())
                .build();

    } catch (KeyStoreException | CertificateException | NoSuchAlgorithmException | IOException | KeyManagementException e) {
        e.printStackTrace();
    }

    return client;
}