Accessing Proxy Settings

Question

Hi,
I am trying to access user's proxy settings in my signed JApplet, but can't find any information about that in documentation. Can someone point me somewhere? I need them because I use Sockets in my program.
Thank you,
Dmitri

Answer 1

Detecting proxy settings that the plug-in is using is tricky stuff... Sun added some (not well documented) support for proxy detection... Try searching the jdc bug db for detect proxy, etc.
The extra jar that needs to be in your classpath during compile (if compiling under 1.3.1) is jre 1.4.1's rt.jar. BTW, we also include javaws.jar because our same JAppplet JARs run under Java Web Start.
I've clobbered together a method (that could use some cleaning:) that takes the URL of a file known to exist (anything from the applet's codebase, eg. settings.prop) & sets a couple booleans & proxy props... Seems to work pretty well except under Mac OS X:
static String proxyIP = "";
static int proxyPort = 80;
static boolean autoDetectProxy = false;  // If SSL version, assume autoDetect, else do not
static boolean useProxy = false;
detectProxy(<codebase file url>);
System.out.println ("Using Proxy:" + useProxy + " Auto Detect Proxy:" + autoDetectProxy + "Proxy IP:" + proxyIP + " Proxy Port:" + proxyPort);
void detectProxy(URL sampleURL) {
    // Added in 5.0.3 -  Plugin 1.4 will hide the internal Sun proxy stuff, so use new proxy property introduced in 1.3.0_1 (1.3.1)...
    // 5.0.7 Update: - Plugin 1.4 Final added com.sun.java.browser.net.* classes ProxyInfo & ProxyService... Use those with JREs => 1.4
    System.out.println(("About to attempt auto proxy detection under Java version:"+javaVers);
    boolean invokeFailover = false; // If specific, known detection methods fail may try fallback detection method
    if (javaVers.startsWith("1.3"))  {    //  Use Sun-specific internal plugin proxy classes for 1.3.X... 1.4.+ nuked this method...
        //  Look around for the 1.3.X plugin proxy detection class... Without it, cannot autodetect...
        try {
            Class t = Class.forName("sun.plugin.protocol.ProxyHandler");
            // Attempt to discover proxy info by asking internal plugin code to locate path to server sampleURL...
            sun.plugin.protocol.ProxyHandler proxyHandler = sun.plugin.protocol.PluginProxyHandler.getDefaultProxyHandler();
            if (proxyHandler != null) {
                try {
                    sun.plugin.protocol.ProxyInfo proxyInfo = proxyHandler.getProxyInfo (sampleURL);
                    if (proxyInfo != null) {
                        // Currently support HTTP non-authenticating proxies.  Authenticating proxies/SOCKS support TDB
                        /* Authenticating proxies need (actually, will need to use Header param of SSLTunneledSocket):
                            String authString = "userid:password";
                            String auth = "BASIC + new sun.misc.BASE64Encoder().encode(authString.getBytes());
                            URL theURL = ....
                            URLConnection urlConn = ....
                            urlConn.setRequestProperty("Proxy-Authorization", auth);
                        useProxy = (proxyInfo.getProxy() != null);
                        if (useProxy) {
                            proxyIP = proxyInfo.getProxy();
                            proxyPort = proxyInfo.getPort();
                            System.out.println("1.3.X proxy " + proxyIP+" port " + proxyPort);
                    else {
                        System.out.println("NULL proxyInfo in 1.3.X auto proxy detection, assuming no proxy...");
                        autoDetectProxy = false;
                catch (Exception e) {
                    System.out.println("Exception during 1.3.X auto proxy detection, will try failover detection, e:"+e);
                    invokeFailover = true;
        catch (Exception ee) {
            System.out.println("Sun Plugin 1.3.X proxy detection class not found, will try failover detection, e:"+ee);
            invokeFailover = true;
    else if (javaVers.startsWith("1.4"))  {
        try {
            //  Look around for the 1.4.X plugin proxy detection class... Without it, cannot autodetect...
            Class t = Class.forName("com.sun.java.browser.net.ProxyService");
            com.sun.java.browser.net.ProxyInfo[] pi = com.sun.java.browser.net.ProxyService.getProxyInfo(sampleURL);
            if (pi == null || pi.length == 0) {
                System.out.println("1.4.X reported NULL proxy (no proxy assumed)");
                useProxy = false;
            else {
                System.out.println("1.4.X Proxy info geProxy:"+pi[0].getHost()+ " get Port:"+pi[0].getPort()+" isSocks:"+pi[0].isSocks());
                useProxy = true;
                proxyIP = pi[0].getHost();
                proxyPort = pi[0].getPort();
                System.out.println("proxy " + proxyIP+" port " + proxyPort);
        catch (Exception ee) {
            System.out.println("Sun Plugin 1.4.X proxy detection class not found, will try failover detection, e:"+ee);
            invokeFailover = true;
    else {
        System.out.println("Sun Plugin reported java version not 1.3.X or 1.4.X, trying failover detection...");
        invokeFailover = true;
    if (invokeFailover) {
        System.out.println("Using failover proxy detection...");
         try {
            String proxyList = ((String)System.getProperties().getProperty("javaplugin.proxy.config.list")).toUpperCase();
            System.out.println("Plugin Proxy Config List Property:"+proxyList);
            useProxy = (proxyList != null);
            if (useProxy) {     //  Using HTTP proxy as proxy for HTTP proxy tunnelled SSL socket (should be listed FIRST)....
                // 6.0.0 1/14/03 1.3.1_06 appears to omit HTTP portion of reported proxy list... Mod to accomodate this...
                // Expecting proxyList of "HTTP=XXX.XXX.XXX.XXX:Port" OR "XXX.XXX.XXX.XXX:Port" & assuming HTTP...
                if (proxyList.indexOf("HTTP=") > -1)
                     proxyIP = proxyList.substring(proxyList.indexOf("HTTP=")+5, proxyList.indexOf(":"));
                else proxyIP = proxyList.substring(0, proxyList.indexOf(":"));
                int endOfPort = proxyList.indexOf(",");
                if (endOfPort < 1) endOfPort = proxyList.length();
                proxyPort = Integer.parseInt(proxyList.substring(proxyList.indexOf(":")+1,endOfPort));
                System.out.println("proxy " + proxyIP+" port " + proxyPort);
        catch (Exception e) {
            System.out.println("Exception during failover auto proxy detection, autoDetect disabled, e:"+e);
            autoDetectProxy = false;
}Good luck,
Chris