<p>Many times, a Java app needs to connect to the Internet. The most common example happens when it is reading an XML file and needs to download its schema.</p>

<p>I am behind a proxy server. How can I set my JVM to use the proxy ?</p>

From the Java documentation (
not
the javadoc API):
http://download.oracle.com/javase/6/docs/technotes/guides/net/proxies.html
Set the JVM flags
```
http.proxyHost
```
and
```
http.proxyPort
```
when starting your JVM on the command line.
This is usually done in a shell script (in Unix) or bat file (in Windows). Here's the example with the Unix shell script:
```
```
JAVA_FLAGS=-Dhttp.proxyHost=10.0.0.100 -Dhttp.proxyPort=8800
java ${JAVA_FLAGS} ...
```
```
When using containers such as JBoss or WebLogic, my solution is to edit the start-up scripts supplied by the vendor.
Many developers are familiar with the Java API (javadocs), but many times the rest of the documentation is overlooked. It contains a lot of interesting information:
http://download.oracle.com/javase/6/docs/technotes/guides/
Update :
If you do not want to use proxy to resolve some local/intranet hosts, check out the comment from @Tomalak:
Also don't forget the http.nonProxyHosts property!
```
```
-Dhttp.nonProxyHosts="localhost|127.0.0.1|10.*.*.*|*.example.com|etc"
```
```