Sun GlassFish Enterprise Server v2.1.1 requires Java SE 5.0 or greater as the underlying JVM. If you want to switch from one Java version to another, perform the following general steps. (Windows and Unix)
Note - Downgrading to an earlier Java version is not recommended after a domain has been created with a newer Java VM. If you must downgrade your JVM, it is recommended that you do it on a per-domain basis. The following procedure describes how to do this.
The Java SDK can be downloaded from http://www.oracle.com/technetwork/java/javase/overview/index.html.
as-install/bin/asadmin start-domain domain-name
In particular, you may want to change the JAVA_HOME variable on the JVM Settings page for the domain.
Alternatively, you can use the asadmin command:
as-install/bin/asadmin set "server.java-config.java-home=path-to-java-home"