If the VM is not already instantiated, it will be now.
If the processID is a normal 16-byte ID, the returned
any contains a JNI JavaVM pointer as a
long or hyper integer (depending on the
platform). If the processID does not match the current
process, or if the VM cannot be instantiated for whatever reason, a
void any is returned.
If the processID has an additional 17th byte of
value 0, the returned any contains a
non–reference-counted pointer to a (reference-counted) instance of
the C++ jvmaccess::VirtualMachine class, always represented
as a hyper integer. The pointer is guaranteed to be valid
as long as the reference to this
XJavaVM is valid (but the
pointer should be converted into a reference-counted reference as soon
as possible). Again, if the first 16 bytes of the
processID do not match the current process, or if the VM
cannot be instantiated for whatever reason, a void any
is returned.
If the processID has an additional 17th byte of
value 1, the returned any contains a
non–reference-counted pointer to a (reference-counted) instance of
the C++ jvmaccess::UnoVirtualMachine class, always
represented as a hyper integer. The pointer is guaranteed
to be valid as long as the reference to this
XJavaVM is valid. Again, if
the first 16 bytes of the processID do not match the
current process, or if the VM cannot be instantiated for whatever
reason, a void any is returned.
The first form (returning a JNI JavaVM pointer) is
mainly for backwards compatibility, new code should use the second form
(returning a pointer to a jvmaccess::VirtualMachine) if it
does not want to use the Java UNO environment, and it should use the
third form (returning a pointer to a
jvmaccess::UnoVirtualMachine) if it wants to use the Java
UNO environment. For example, one advantage of using
jvmaccess::VirtualMachine instead of the raw
JavaVM pointer is that whenever you attach a native thread
to the Java virtual machine, that thread's context
ClassLoader (see
java.lang.Thread.getContextClassLoader) will automatically
be set to a meaningful value.
