Java Reference
In-Depth Information
System Properties
For basic operations, all you have to do is set a few system properties to point to the
addresses of your local proxy servers. If you are using a pure HTTP proxy, set
http.proxyHost
to the domain name or the IP address of your proxy server and
http.proxyPort
to the port of the proxy server (the default is 80). There are several
ways to do this, including calling
System.setProperty()
from within your Java code
or using the
-D
options when launching the program. This example sets the proxy server
to 192.168.254.254 and the port to 9000:
<
programlisting
format
=
"linespecific"
id
=
"I_7_tt264"
>%
<
userinput
moreinfo
=
"none"
>
java
-
Dhttp
.
proxyHost
=
192.168
.
254.254
-
Dhttp
.
proxyPort
=
9000
</
userinput
>
<
emphasis
role
=
"bolditalic"
>
com
.
domain
.
Program
</
emphasis
></
programlisting
>
If the proxy requires a username and password, you'll need to install an
Authentica
tor
, as we'll discuss shortly in
“Accessing Password-Protected Sites” on page 161
.
If you want to exclude a host from being proxied and connect directly instead, set the
http.nonProxyHosts
system property to its hostname or IP address. To exclude mul‐
tiple hosts, separate their names by vertical bars. For example, this code fragment proxies
everything except
java.oreilly.com
and
xml.oreilly.com
:
System
.
setProperty
(
"http.proxyHost"
,
"192.168.254.254"
);
System
.
setProperty
(
"http.proxyPort"
,
"9000"
);
System
.
setProperty
(
"http.nonProxyHosts"
,
"java.oreilly.com|xml.oreilly.com"
);
You can also use an asterisk as a wildcard to indicate that all the hosts within a particular
domain or subdomain should not be proxied. For example, to proxy everything except
hosts in the
oreilly.com
domain:
%
java
-
Dhttp
.
proxyHost
=
192.168
.
254.254
-
Dhttp
.
nonProxyHosts
=*.
oreilly
.
com
<
emphasis
role
=
"bolditalic"
>
com
.
domain
.
Program
</
emphasis
></
programlisting
>
If you are using an FTP proxy server, set the
ftp.proxyHost
,
ftp.proxyPort
, and
ftp.nonProxyHosts
properties in the same way.
Java does not support any other application layer proxies, but if you're using a transport
layer SOCKS proxy for all TCP connections, you can identify it with the
socksProxy
Host
and
socksProxyPort
system properties. Java does not provide an option for non‐
proxying with SOCKS. It's an all-or-nothing decision.
The Proxy Class
The
Proxy
class allows more fine-grained control of proxy servers from within a Java
program. Specifically, it allows you to choose different proxy servers for different remote
hosts. The proxies themselves are represented by instances of the
java.net.Proxy
class.
