Estoy creando una aplicación que verifica periódicamente algunas fuentes rss para ver si hay contenido nuevo. Algunas de estas fuentes solo son accesibles a través de https y otras tienen certificados autofirmados o rotos. Quiero poder comprobarlos nunca menos.

Tenga en cuenta que la seguridad no es un problema en esta aplicación, el objetivo es acceder al contenido con el mínimo esfuerzo.

Estoy usando este código para sortear la mayoría de los problemas de certificados:

/**
     * Sets timeout values and user agent header, and ignores self signed ssl
     * certificates to enable maximum coverage
     * 
     * @param con
     * @return
     */
    public static URLConnection configureConnection(URLConnection con)
    {
        con.setRequestProperty(
            "User-Agent",
            "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.11 (KHTML, like Gecko) Chrome/23.0.1271.95 Safari/537.11");
        con.setConnectTimeout(30000);
        con.setReadTimeout(40000);
        if (con instanceof HttpsURLConnection)
        {
            HttpsURLConnection conHttps = (HttpsURLConnection) con;
            TrustManager[] trustAllCerts = new TrustManager[] { new X509TrustManager()
            {

                public java.security.cert.X509Certificate[] getAcceptedIssuers()
                {
                    return null;
                }

                public void checkClientTrusted(
                    java.security.cert.X509Certificate[] certs, String authType)
                {
                }

                public void checkServerTrusted(
                    java.security.cert.X509Certificate[] certs, String authType)
                {
                }
            } };

            HostnameVerifier allHostsValid = new HostnameVerifier()
            {
                @Override
                public boolean verify(String arg0, SSLSession arg1)
                {
                    return true;
                }
            };

            // Install the all-trusting trust manager
            try
            {
                SSLContext sc = SSLContext.getInstance("SSL");
                sc.init(null, trustAllCerts, new java.security.SecureRandom());
                HttpsURLConnection.setDefaultSSLSocketFactory(sc
                    .getSocketFactory());
                HttpsURLConnection.setDefaultHostnameVerifier(allHostsValid);
                con = conHttps;
            } catch (Exception e)
            {
            }
        }
        return con;
    }

esto funciona para la mayoría de los sitios, pero en uno todavía obtengo esta excepción:

javax.net.ssl.SSLHandshakeException: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification pat
h to requested target
        at sun.security.ssl.Alerts.getSSLException(Alerts.java:192)
        at sun.security.ssl.SSLSocketImpl.fatal(SSLSocketImpl.java:1715)
        at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:257)
        at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:251)
        at sun.security.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1168)
        at sun.security.ssl.ClientHandshaker.processMessage(ClientHandshaker.java:153)
        at sun.security.ssl.Handshaker.processLoop(Handshaker.java:609)
        at sun.security.ssl.Handshaker.process_record(Handshaker.java:545)
        at sun.security.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:963)
        at sun.security.ssl.SSLSocketImpl.performInitialHandshake(SSLSocketImpl.java:1208)
        at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1235)
        at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1219)
        at sun.net.www.protocol.https.HttpsClient.afterConnect(HttpsClient.java:440)
        at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(AbstractDelegateHttpsURLConnection.java:185)
        at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1139)
        at java.net.HttpURLConnection.getResponseCode(HttpURLConnection.java:397)
        at sun.net.www.protocol.https.HttpsURLConnectionImpl.getResponseCode(HttpsURLConnectionImpl.java:338)
        at crawler.RSSReader.getNewArticles(RSSReader.java:53)
        at crawler.Crawler.fetchFeed(Crawler.java:187)
        at crawler.Crawler.main(Crawler.java:120)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:622)
        at org.eclipse.jdt.internal.jarinjarloader.JarRsrcLoader.main(JarRsrcLoader.java:58)
Caused by: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
        at sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:324)
        at sun.security.validator.PKIXValidator.engineValidate(PKIXValidator.java:224)
        at sun.security.validator.Validator.validate(Validator.java:235)
        at sun.security.ssl.X509TrustManagerImpl.validate(X509TrustManagerImpl.java:147)
        at sun.security.ssl.X509TrustManagerImpl.checkServerTrusted(X509TrustManagerImpl.java:230)
        at sun.security.ssl.X509TrustManagerImpl.checkServerTrusted(X509TrustManagerImpl.java:270)
        at sun.security.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1147)
        ... 20 more
Caused by: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
        at sun.security.provider.certpath.SunCertPathBuilder.engineBuild(SunCertPathBuilder.java:197)
        at java.security.cert.CertPathBuilder.build(CertPathBuilder.java:255)
        at sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:319)

¿Alguien sabe cómo puedo resolver esto?