Asked  7 Months ago    Answers:  5   Viewed   63 times

Many times, a Java app needs to connect to the Internet. The most common example happens when it is reading an XML file and needs to download its schema.

I am behind a proxy server. How can I set my JVM to use the proxy ?



From the Java documentation (not the javadoc API):

Set the JVM flags http.proxyHost and http.proxyPort when starting your JVM on the command line. This is usually done in a shell script (in Unix) or bat file (in Windows). Here's the example with the Unix shell script:

JAVA_FLAGS=-Dhttp.proxyHost= -Dhttp.proxyPort=8800
java ${JAVA_FLAGS} ...

When using containers such as JBoss or WebLogic, my solution is to edit the start-up scripts supplied by the vendor.

Many developers are familiar with the Java API (javadocs), but many times the rest of the documentation is overlooked. It contains a lot of interesting information:

Update : If you do not want to use proxy to resolve some local/intranet hosts, check out the comment from @Tomalak:

Also don't forget the http.nonProxyHosts property!

Tuesday, June 1, 2021
answered 7 Months ago

Edit for iOS 11+ only

Use WKHTTPCookieStore:

let cookie = HTTPCookie(properties: [
    .domain: "",
    .path: "/",
    .name: "MyCookieName",
    .value: "MyCookieValue",
    .secure: "TRUE",
    .expires: NSDate(timeIntervalSinceNow: 31556926)


Since you are pulling them over from HTTPCookeStorage, you can do this:

let cookies = HTTPCookieStorage.shared.cookies ?? []
for cookie in cookies {

Old answer for iOS 10 and below

If you require your cookies to be set on the initial load request, you can set them on NSMutableURLRequest. Because cookies are just a specially formatted request header this can be achieved like so:

WKWebView * webView = /*set up your webView*/
NSMutableURLRequest * request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:@""]];
[request addValue:@"TeskCookieKey1=TeskCookieValue1;TeskCookieKey2=TeskCookieValue2;" forHTTPHeaderField:@"Cookie"];
// use stringWithFormat: in the above line to inject your values programmatically
[webView loadRequest:request];

If you require subsequent AJAX requests on the page to have their cookies set, this can be achieved by simply using WKUserScript to set the values programmatically via javascript at document start like so:

WKUserContentController* userContentController =;
WKUserScript * cookieScript = [[WKUserScript alloc] 
    initWithSource: @"document.cookie = 'TeskCookieKey1=TeskCookieValue1';document.cookie = 'TeskCookieKey2=TeskCookieValue2';"
    injectionTime:WKUserScriptInjectionTimeAtDocumentStart forMainFrameOnly:NO];
// again, use stringWithFormat: in the above line to inject your values programmatically
[userContentController addUserScript:cookieScript];
WKWebViewConfiguration* webViewConfig =;
webViewConfig.userContentController = userContentController;
WKWebView * webView = [[WKWebView alloc] initWithFrame:CGRectMake(/*set your values*/) configuration:webViewConfig];

Combining these two techniques should give you enough tools to transfer cookie values from Native App Land to Web View Land. You can find more info on the cookie javascript API on Mozilla's page if you require some more advanced cookies.

Yeah, it sucks that Apple is not supporting many of the niceties of UIWebView. Not sure if they will ever support them, but hopefully they will get on this soon. Hope this helps!

Tuesday, June 1, 2021
answered 7 Months ago

There is another method for handling this.

You can add an event listener to the DOM elements and intercept it that way.


NodeList nodeList = document.getElementsByTagName("a");
            for (int i = 0; i < nodeList.getLength(); i++)
                Node node= nodeList.item(i);
                EventTarget eventTarget = (EventTarget) node;
                eventTarget.addEventListener("click", new EventListener()
                    public void handleEvent(Event evt)
                        EventTarget target = evt.getCurrentTarget();
                        HTMLAnchorElement anchorElement = (HTMLAnchorElement) target;
                        String href = anchorElement.getHref();
                        //handle opening URL outside JavaFX WebView
                }, false);

Where document is the DOM document object. Make sure this is done after the document has finished loading.

Thursday, July 29, 2021
answered 4 Months ago

Take a look at my question here:

You can specify a location on the classpath by setting the feature attribute in the options annotation like



in new versions code is

Monday, August 2, 2021
answered 4 Months ago

I suspect your NullPointerException is occurring because yc.getInputStream() is returning null. You need to check that it is returning some non-null value before you attempt to create a reader to read bytes from it.

As for the proxy issue, you can pass a Proxy object to the connection, e.g.:

Proxy proxy = new Proxy(Proxy.Type.HTTP, new InetSocketAddress("", 3128));
URLConnection yc = url.openConnection(proxy);

This might at least allow you to interrogate the Proxy and rule out potential sources for the problem (there are several, as it stands).

This thread might have some useful hints for getting your proxy username and password string working properly. The article you linked looks slightly out of date.

Saturday, November 6, 2021
Sotirios Delimanolis
answered 4 Weeks ago
Only authorized users can answer the question. Please sign in first, or register a free account.
Not the answer you're looking for? Browse other questions tagged :