Java, let CookieHandler work on only one instance

Question

I don't know how CookieHandler works system wide, I did view the source of CookieHandler but found no more information except the get/set methods. Where do TCP/HTTP connections use instance of CookieHandler, which I set by

CookieHandler.setDefault(...)

Which source file I should refer to? URLConnection & HttpURLConnection don't seem have things to do with it.

Help, thanks in advance.

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Edit: Is it possible to apply CookieHandler to only one instance in which setDefault is invoked.

Answer 1

I got it working by using this

private static class DelegatingCookieManager extends CookieManager {
    @Override public void setCookiePolicy(CookiePolicy cookiePolicy) {
        delegate.get().setCookiePolicy(cookiePolicy);
    }

    @Override public CookieStore getCookieStore() {
        return delegate.get().getCookieStore();
    }

    @Override public Map<String, List<String>> get(
            URI uri, Map<String, List<String>> requestHeaders)
            throws IOException {
        return delegate.get().get(uri, requestHeaders);
    }

    @Override public void put(URI uri, Map<String,
            List<String>> responseHeaders)
            throws IOException {
        delegate.get().put(uri, responseHeaders);
    }
}

which gets installed globally

static {
    CookieHandler.setDefault(new DelegatingCookieManager());
}

but has no state and delegate to a

private static final ThreadLocal<CookieManager> delegate =
     new ThreadLocal<CookieManager>();

which gets instantiated in the class where it gets used

private final CookieManager ownCookieManager = new CookieManager();

like

delegate.set(ownCookieManager);
doRequest();