Cannot login into Salesforce with Java using Proxy Server

Question

I wrote Java code to login to Salesforce and ran this code on a firewalled server. For this, I have to specify the proxy url and proxy port before connecting to Salesforce due to the firewall. However, I'm getting an unknownhostexception error for the proxy url. If I try to login via curl with the proxy settings, I am able to connect. How come there is a problem connecting using Java then? Any help is appreciated.

Java code :

        System.setProperty("https.protocols", "TLSv1,TLSv1.1,TLSv1.2");
        ConnectorConfig partnerConfig = new ConnectorConfig();
        partnerConfig.setUsername(crmUsername);
        partnerConfig.setPassword(crmPwd);
        partnerConfig.setAuthEndpoint(crmServer + "/services/Soap/u/38.0");
        partnerConfig.setProxy(this.proxyUrl, this.proxyPort);
        // Creating the connection automatically handles login and stores
        // the session in partnerConfig
        try {
            pConn = new PartnerConnection(partnerConfig);
        } catch (ConnectionException e) {
            e.printStackTrace();
            if (e instanceof ApiFault) {
                return ((ApiFault) e).getExceptionMessage();
            }
        }

        // When PartnerConnection is instantiated, a login is implicitly
        // executed and, if successful,
        // a valid session is stored in the ConnectorConfig instance.
        // Use this key to initialize a BulkConnection:
        ConnectorConfig config = new ConnectorConfig();
        config.setSessionId(partnerConfig.getSessionId());
        // The endpoint for the Bulk API service is the same as for the normal
        // SOAP uri until the /Soap/ part. From here it's '/async/versionNumber'
        String soapEndpoint = partnerConfig.getServiceEndpoint();
        String apiVersion = "38.0";
        String restEndpoint = soapEndpoint.substring(0, soapEndpoint.indexOf("Soap/")) + "async/" + apiVersion;
        config.setRestEndpoint(restEndpoint);
        // This should only be false when doing debugging.
        config.setCompression(false);
        // Set this to true to see HTTP requests and responses on stdout
        config.setTraceMessage(true);
        config.setProxy(this.proxyUrl, this.proxyPort);

        try {
            bConn = new BulkConnection(config);
        } catch (AsyncApiException e) {
            e.printStackTrace();
            return e.getMessage();
        }

Answer 1

Adding the following code before establishing a connection fixed it.

System.setProperty("http.proxyHost", crmProxyURL);
System.setProperty("http.proxyPort", crmProxyPort);