How do I make HttpURLConnection use a proxy?

Question

If I do this...

conn = new URL(urlString).openConnection();
System.out.println("Proxy? " + conn.usingProxy());

it prints

Proxy? false

The problem is, I am behind a proxy. Where does the JVM get its proxy information from on Windows? How do I set this up? All my other apps seem perfectly happy with my proxy.

Weig

Answer 1

Since java 1.5 you can also pass a java.net.Proxy instance to the openConnection(proxy) method:

//Proxy instance, proxy ip = 10.0.0.1 with port 8080
Proxy proxy = new Proxy(Proxy.Type.HTTP, new InetSocketAddress("10.0.0.1", 8080));
conn = new URL(urlString).openConnection(proxy);

If your proxy requires authentication it will give you response 407.

In this case you'll need the following code:

    Authenticator authenticator = new Authenticator() {

        public PasswordAuthentication getPasswordAuthentication() {
            return (new PasswordAuthentication("user",
                    "password".toCharArray()));
        }
    };
    Authenticator.setDefault(authenticator);

Cortisone

can we provide proxy username and proxy password through it. – Loving

Exactly what I was looking. And yet I accidentally clicked downvote while copy/pasting, only to notice too late to undo it. Sorry. – Mete

What if you have different username/password pairs for the different proxies? Calling a static method to set the default Authenticator isn't ideal, this is not much better than setting the sys properties method.. – Mellophone

I'm trying to use this to check connection with google.com but getResponseCode() returns recvfrom failed: ECONNRESET (Connection reset by peer) exception. ¿what would be wrong? – Albumose

Do we have to call Authenticator every time we open a HttpURLConnection? Or set this only once? – Spirituality

Authenticator.default is a static (i.e. global) variable, so it's only once. But please note that the Authenticator above is just a minimal example. It can only handle one password at a time. Google for examples that can handle multiple hosts with different passwords. – Dishcloth

Since 8u11 this will not work by default with Basic authentication, oracle.com/technetwork/java/javase/8u111-relnotes-3124969.html jdk.http.auth.tunneling.disabledSchemes system property must be set to emtpty – Maimaia

In case you have domain. Do as following: new PasswordAuthentication("domainName\\user", "password".toCharArray()); – Tomokotomorrow

@NickDK, Your answer is very good and easy to understand, I was looking for the same piece of code, but I am getting " java.net.SocketTimeoutException: connect timed out " while establishing the connecting. Can someone please guide me – Evolutionist

for multiple proxies, instead of using an Authenticator like in the example, just setting the 'Proxy-Authorization' header is enough, but may not always fit your requirements, for details see: developer.mozilla.org/en-US/docs/Web/HTTP/Headers/… – Jacinto

@Chris, I would like to clarify your statement: "just setting the 'Proxy-Authorization'" & , "but may not always fit your requirements". If proxy requires NTLM authentication other than Basic authentication, setting 'Proxy-Authorization' will not be as simple as in case of Basic auth. – Pastose

The Authenticator part resolved the issue for me using the okhttp3 library as well using a SOCKS5 proxy. – Gushy

How to read cookie from target and write to response for user browser? – Lexeme

Answer 2

This is fairly easy to answer from the internet. Set system properties http.proxyHost and http.proxyPort. You can do this with System.setProperty(), or from the command line with the -D syntax. EDIT: per comment, set https.proxyPort and https.proxyHost for HTTPS.

Enciso

Please edit your answer to include for the scenario when it's https. If you connect to a https endpoint you have to use https.proxyHost and https.proxyPort. – Upandcoming

Although your answer seems to be correct, it lacks details. Please add some code examples as to how to use these properties. – Ingeringersoll

Answer 3

Proxies are supported through two system properties: http.proxyHost and http.proxyPort. They must be set to the proxy server and port respectively. The following basic example illustrates it:

String url = "http://www.google.com/",
       proxy = "proxy.mydomain.com",
       port = "8080";
URL server = new URL(url);
Properties systemProperties = System.getProperties();
systemProperties.setProperty("http.proxyHost",proxy);
systemProperties.setProperty("http.proxyPort",port);
HttpURLConnection connection = (HttpURLConnection)server.openConnection();
connection.connect();
InputStream in = connection.getInputStream();
readResponse(in);

Tempa

@Pascal Do you happen to know what are the major differences of using latest Java approach in comparison to Apache commons-httpclient? As Java supports proxying and authentication (as you mentioned here #1627049), for simple cases (like retrieve one file from public HTTP server) there is no reason to use Apache library. What is your recommendation? – Affiant

@Affiant I agree with you, for simple use cases like the one you described I wouldn't use a third party library. – Tempa

Do you know how to support the nonProxyHosts? I see that my device support it but doesn't know how to make my app handle it. – Endoplasm

But variable systemProperties is not used by the connection! – Heroin

How to pass read cookie ??? – Lexeme

Answer 4

You can also set

-Djava.net.useSystemProxies=true

On Windows and Linux this will use the system settings so you don't need to repeat yourself (DRY)

http://docs.oracle.com/javase/7/docs/api/java/net/doc-files/net-properties.html#Proxies

Terrarium

This works only with manual proxy server configuration. Automatic proxy configuration and proxies configured through script are not (yet) propagated to "useSystemProxies". – Pilsner

This worked for me when setting the proxyHost and proxyPort didn't. Thanks! – Euxenite

Likewise, this worked from behind my company proxy when calls to System.setProperty for the https.proxyHost and https.proxyPort for some reason weren't cutting the mustard. – Danas

Answer 5

Set following before you openConnection,

System.setProperty("http.proxyHost", "host");
System.setProperty("http.proxyPort", "port_number");

If proxy requires authentication,

System.setProperty("http.proxyUser", "user");
System.setProperty("http.proxyPassword", "password");

Ridings

I actually think "http.proxyUser" and "http.proxyPassword" are not supported anymore. See #121297 for more details. – Kame

Answer 6

For Java 1.8 and higher you must set -Djdk.http.auth.tunneling.disabledSchemes= to make proxies with Basic Authorization working with https.

Parnassus

Background information about this is discussed at #41806922 – Nolasco

Answer 7

The approved answer will work ... if you know your proxy host and port =) . But in case you are looking for the proxy host and port the steps below should help

if auto configured proxy is given: then

1> open IE(or any browser)

2> get the url address from your browser through IE->Tools->internet option->connections->LAN Settings-> get address and give in url eg: as http://autocache.abc.com/ and enter, a file will be downloaded with .pac format, save to desktop

3> open .pac file in textpad, identify PROXY:

In your editor, it will come something like:

return "PROXY web-proxy.ind.abc.com:8080; PROXY proxy.sgp.abc.com:8080";

kudos to bekur from maven in 5 min not working

Once you have the host and port just pop in into this and your good to go

Proxy proxy = new Proxy(Proxy.Type.HTTP, new InetSocketAddress("web-proxy.ind.abc.com", 8080));
        URLConnection connection = new URL(url).openConnection(proxy);

Receptacle