Set Java Proxy for Http/Https

 Command Line JVM Settings

The proxy settings are given to the JVM via command line arguments:

 java -Dhttp.proxyHost=proxyhostURL
-Dhttp.proxyPort=proxyPortNumber
-Dhttp.proxyUser=someUserName
-Dhttp.proxyPassword=somePassword HelloWorldClass

Setting System Properties in Code

Add the following lines in your Java code so that JVM uses the proxy to make HTTP calls. This would, of course, require you to recompile your Java source. (The other methods do not require any recompilation):

System.getProperties().put("http.proxyPort", "someProxyPort");
System.getProperties().put("http.proxyUser", "someUserName");
System.getProperties().put("http.proxyPassword", "somePassword");
System.getProperties().put("http.proxyHost", "someProxyURL");

One more configuraiton for Microsoft ISA NTLM Authentication

You need add below in addition is the proxy using NTLM authentication.
-Dhttp.auth.ntlm.domain=DOMAIN

Configuring Authentication Order

There are three authentication mechanisms provided - ntlm, digest & basic in that order by default. It is possible to change the order and also not exclude one or more methods altogether. This can be done with the following property.

-Dhttp.proxyAuth=basic,ntlm

In this example the authentication order will be basic and then ntlm only - digest will not be used.

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

//Proxy instance, proxy ip = 123.0.0.1 with port 8080
Proxy proxy = new Proxy(Proxy.Type.HTTP, new InetSocketAddress("123.0.0.1", 8080));
URL url = new URL("http://www.yahoo.com");
HttpURLConnection uc = (HttpURLConnection)url.openConnection(proxy);
uc.connect();

String page;
StringBuffer tmp = new StringBuffer();
BufferedReader in = new BufferedReader(new InputStreamReader(uc.getInputStream()));
while ((line = in.readLine()) != null){
   page.append(line + "\n");
}
System.out.println(page);

so you don't need to set system properties. You can use the default PROXY as defined by your networking settings.

System.setProperty("java.net.useSystemProxies", "true");
List l = null;
try {
  l = ProxySelector.getDefault().select(new URI("http://www.yahoo.com"));
}
catch (URISyntaxException e) {
  e.printStackTrace();
}

if (l != null) {
   for (Iterator iter = l.iterator(); iter.hasNext() {
      java.net.Proxy proxy = (java.net.Proxy) iter.next();
      System.out.println("proxy hostname : " + proxy.type());
      InetSocketAddress addr = (InetSocketAddress) proxy.address();
      if (addr == null) {
        System.out.println("No Proxy");
      }
      else {
        System.out.println("proxy hostname : " + addr.getHostName());
        System.out.println("proxy port : " + addr.getPort());
      }
   }
}

To bypass the PROXY,

URL url = new URL("http://internal.server.local/");
URLConnection conn = url.openConnection(Proxy.NO_PROXY);

Proxy and Username/Password

You might need to identify yourself to the proxy server.

One way is to use the HTTP property "Proxy-Authorization" with a username:password base64 encoded.

System.setProperty("http.proxyHost", "myProxyServer.com");
System.setProperty("http.proxyPort", "80");
URL url=new URL("http://someserver/somepage");
URLConnection uc = url.openConnection ();
String encoded = new String
      (Base64.base64Encode(new String("username:password").getBytes()));
uc.setRequestProperty("Proxy-Authorization", "Basic " + encoded);
uc.connect();

The following example dumps the content of a URL but before we identify ourself to the proxy.

import java.net.*;
import java.io.*;

public class URLUtils {
  public static void main(String s[]) {
    URLUtils.dump("http://www.yahoo.com");
    System.out.println("**************");
    URLUtils.dump("https://www.paypal.com");
    System.out.println("**************");
  }

  public static void dump(String URLName){
    try {
      DataInputStream di = null;
      FileOutputStream fo = null;
      byte [] b = new byte[1];

      // PROXY
      System.setProperty("http.proxyHost","proxy.mydomain.local") ;
      System.setProperty("http.proxyPort", "80") ;

      URL u = new URL(URLName);
      HttpURLConnection con = (HttpURLConnection) u.openConnection();
      //
      // it's not the greatest idea to use a sun.misc.* class
      // Sun strongly advises not to use them since they can
      // change or go away in a future release so beware.
      //
      sun.misc.BASE64Encoder encoder = new sun.misc.BASE64Encoder();
      String encodedUserPwd =
         encoder.encode("mydomain\\MYUSER:MYPASSWORD".getBytes());
      con.setRequestProperty
         ("Proxy-Authorization", "Basic " + encodedUserPwd);
      // PROXY ----------

      di = new DataInputStream(con.getInputStream());
      while(-1 != di.read(b,0,1)) {
         System.out.print(new String(b));
      }
    }
    catch (Exception e) {
      e.printStackTrace();
    }
  }
}

With JDK1.2, the java.net.Authenticator can be used to send the credentials when needed.

public static void dump(String URLName){
  try {
    DataInputStream di = null;
    FileOutputStream fo = null;
    byte [] b = new byte[1];

    // PROXY
    System.setProperty("http.proxyHost","proxy.mydomain.local") ;
    System.setProperty("http.proxyPort", "80") ;

    Authenticator.setDefault(new Authenticator() {
      protected PasswordAuthentication getPasswordAuthentication() {
        return new
           PasswordAuthentication("mydomain\\username","password".toCharArray());
    }});

    URL u = new URL(URLName);
    HttpURLConnection con = (HttpURLConnection) u.openConnection();
    di = new DataInputStream(con.getInputStream());
    while(-1 != di.read(b,0,1)) {
       System.out.print(new String(b));
    }
  }
  catch (Exception e) {
          e.printStackTrace();
  }
}

Bypass a Proxy

In intranet environment, you may need to bypass the proxy server and go directly to the http server.

The http.nonProxyHosts property indicates the hosts which should be connected too directly and not through the proxy server. The value can be a list of hosts, each seperated by a |, and in addition a wildcard character (*) can be used for matching.

java.exe  -Dhttp.nonProxyHosts="*.mycompany.com|*.mycompany.local|localhost" MyClass

Below are  the Networking Properties from http://docs.oracle.com/javase/7/docs/api/java/net/doc-files/net-properties.html

There are a few standard system properties used to alter the mechanisms and behavior of the various classes of the java.net package.
Some are checked only once at startup of the VM, and therefore are best set using the -D option of the java command,
while others have a more dynamic nature and can also be changed using the System.setProperty() API.
The purpose of this document is to list and detail all of these properties.
If there is no special note, a property value is checked every time it is used.

• IPv4 / IPv6

java.net.preferIPv4Stack (default: false)
If IPv6 is available on the operating system the underlying native socket will be, by default,
an IPv6 socket which lets applications connect to, and accept connections from, both IPv4 and IPv6 hosts.
However, in the case an application would rather use IPv4 only sockets, then this property can be set to true.
The implication is that it will not be possible for the application to communicate with IPv6 only hosts.

java.net.preferIPv6Addresses (default: false)
When dealing with a host which has both IPv4 and IPv6 addresses, and if IPv6 is available on the operating system,
the default behavior is to prefer using IPv4 addresses over IPv6 ones. This is to ensure backward compatibility,
for example applications that depend on the representation of an IPv4 address (e.g. 192.168.1.1).
This property can be set to true to change that preference and use IPv6 addresses over IPv4 ones where possible.

Both of these properties are checked only once, at startup.

• Proxies

A proxy server allows indirect connection to network services and is used mainly for security (to get through firewalls)
and performance reasons (proxies often do provide caching mechanisms).
The following properties allow for configuration of the various type of proxies.

• HTTP

The following proxy settings are used by the HTTP protocol handler.

http.proxyHost (default: <none>) The hostname, or address, of the proxy server

http.proxyPort (default: 80) The port number of the proxy server.

http.nonProxyHosts (default: localhost|127.*|[::1])

Indicates the hosts that should be accessed without going through the proxy. Typically this defines internal hosts.
The value of this property is a list of hosts, separated by the '|' character.
In addition the wildcard character '*' can be used for pattern matching.

For example -Dhttp.nonProxyHosts=”*.foo.com|localhost” will indicate that every hosts in the foo.com domain
and the localhost should be accessed directly even if a proxy server is specified.

The default value excludes all common variations of the loopback address.

• HTTPS

This is HTTP over SSL, a secure version of HTTP mainly used when confidentiality (like on payment sites) is needed.

The following proxy settings are used by the HTTPS protocol handler.

https.proxyHost(default: <none>)
The hostname, or address, of the proxy server

https.proxyPort (default: 443)
The port number of the proxy server.

The HTTPS protocol handler will use the same nonProxyHosts property as the HTTP protocol.

• FTP

The following proxy settings are used by the FTP protocol handler.

ftp.proxyHost(default: <none>)
The hostname, or address, of the proxy server

ftp.proxyPort (default: 80)
The port number of the proxy server.

ftp.nonProxyHosts (default: localhost|127.*|[::1])
Indicates the hosts that should be accessed without going through the proxy. Typically this defines internal hosts.
The value of this property is a list of hosts, separated by the '|' character. In addition the wildcard character '*' can be
used for pattern matching.

For example -Dftp.nonProxyHosts=”*.foo.com|localhost” will indicate that every hosts in the foo.com
domain and the localhost should be accessed directly even if a proxy server is specified.

The default value excludes all common variations of the loopback address.

• SOCKS

This is another type of proxy. It allows for lower level type of tunneling since it works at the TCP level.
In effect, in the Java(tm) platform setting a SOCKS proxy server will result in all TCP connections to go through that proxy,
unless other proxies are specified. If SOCKS is supported by a Java SE implementation, the following properties will be used:

socksProxyHost (default: <none>)
The hostname, or address, of the proxy server.

socksProxyPort (default: 1080)
The port number of the proxy server.

socksProxyVersion (default: 5)
The version of the SOCKS protocol supported by the server. The default is 5 indicating SOCKS V5, alternatively 4 can be specified for SOCKS V4.
Setting the property to values other than these leads to unspecified behavior.

java.net.socks.username (default: <none>)
Username to use if the SOCKSv5 server asks for authentication and no java.net.Authenticator instance was found.

java.net.socks.password (default: <none>)
Password to use if the SOCKSv5 server asks for authentication and no java.net.Authenticator instance was found.

Note that if no authentication is provided with either the above properties or an Authenticator, and the proxy requires one,
then the user.name property will be used with no password.

java.net.useSystemProxies (default: false)
On recent Windows systems and on Gnome 2.x systems it is possible to tell the java.net stack, setting this property to true,
to use the system proxy settings (both these systems let you set proxies globally through their user interface).
Note that this property is checked only once at startup.

• Misc HTTP properties

http.agent (default: “Java/<version>”)
Defines the string sent in the User-Agent request header in http requests. Note that the string “Java/<version>” will be appended
to the one provided in the property (e.g. if -Dhttp.agent=”foobar” is used, the User-Agent header will contain “foobar Java/1.5.0”
if the version of the VM is 1.5.0). This property is checked only once at startup.

http.keepalive (default: true)
Indicates if persistent connections should be supported. They improve performance by allowing the underlying socket
connection to be reused for multiple http requests. If this is set to true then persistent connections will be requested with HTTP 1.1 servers.

http.maxConnections (default: 5)
If HTTP keepalive is enabled (see above) this value determines the maximum number of idle connections that will be simultaneously kept alive,
per destination.

http.maxRedirects (default: 20)
This integer value determines the maximum number, for a given request, of HTTP redirects that will be automatically followed by the protocol handler.

http.auth.digest.validateServer (default: false)

http.auth.digest.validateProxy (default: false)

http.auth.digest.cnonceRepeat (default: 5)

These 3 properties modify the behavior of the HTTP digest authentication mechanism. Digest authentication
provides a limited ability for the server to authenticate itself to the client (i.e. By proving it knows the user's password).

However not all HTTP servers support this capability and by default it is turned off.
The first two properties can be set to true to enforce this check for authentication with either an origin or proxy server, respectively.

It is usually not necessary to change the third property. It determines how many times a cnonce value is re-used.
This can be useful when the MD5-sess algorithm is being used. Increasing this value reduces the computational overhead
on both client and server by reducing the amount of material that has to be hashed for each HTTP request.

http.auth.ntlm.domain (default: <none>)
NTLM is another authentication scheme. It uses the java.net.Authenticator class to acquire usernames and passwords
when they are needed. However NTLM also needs the NT domain name. There are 3 options for specifying that domain:

Do not specify it. In some environments the domain is actually not required and the application does not have to specify it.

The domain name can be encoded within the username by prefixing the domain name, followed by a back-slash '\' before the username.
With this method existing applications that use the authenticator class do not need to be modified,
as long as users are made aware that this notation must be used.

If a domain name is not specified as in method 2) and these property is defined, then its value will be used a the domain name.
All these properties are checked only once at startup.

• Address Cache

The java.net package, when doing name resolution, uses an address cache for both security and performance reasons.
Any address resolution attempt, be it forward (name to IP address) or reverse (IP address to name),
will have its result cached, whether it was successful or not, so that subsequent identical requests will not have to access the naming service.
These properties allow for some tuning on how the cache is operating.

networkaddress.cache.ttl (default: see below)

Value is an integer corresponding to the number of seconds successful name lookups will be kept in the cache. A value of -1,
or any other negative value for that matter, indicates a “cache forever” policy, while a value of 0 (zero) means no caching.
The default value is -1 (forever) if a security manager is installed, and implementation specific when no security manager is installed.

networkaddress.cache.negative.ttl (default: 10)

Value is an integer corresponding to the number of seconds an unsuccessful name lookup will be kept in the cache. A value of -1,
or any negative value, means “cache forever”, while a value of 0 (zero) means no caching.

Since these 2 properties are part of the security policy, they are not set by either the -D option or the System.setProperty() API,
instead they are set in the JRE security policy file lib/security/java.security.

http://docs.oracle.com/javase/6/docs/technotes/guides/net/properties.html