Howto maven2 download java source jar package

$> mvn dependency:sources -Dsilent=true filename
dependency:sources tells Maven to resolve all dependencies and their source attachments, and displays the version.

maven plugins lists page:
http://maven.apache.org/plugins/maven-dependency-plugin/
http://maven.apache.org/plugins/index.html

Reference:
http://groups.google.com/group/maven-zh/browse_thread/thread/20494aa10d7818ba?pli=1