Eclipse RCP：检查本机库

Question

In an Eclispe RCP application, is there a way to check whether a specific native library is available on the current system?

Using System.loadLibrary("myLib"); and then catching an UnsatisfiedLinkError results in other bundles not being able to use the library, as this would lead to an error "Library already loaded by another class loader".

I've found a solution to this problem on the internet which uses a custom class loader, which then loads the library and then the class loader is garbage collected with System.gc(), which will also unload the library so it can be loaded again by another bundle.

There are disadvantages however:

1. It requires a lot of custom code
2. Catching UnsatfisfiedLinkError is somewhat scary
3. Say Bundle1 loads the library to check for availability. Then Bundle1 unloads the library and Bundle2 loads the library to actually use it. Bundle2 does not unload the library (as there is no reason to do so). Then, Bundle1 again wants to load the library to check for availability. This again will lead to an UnsatisfiedLinkError.

Answer 1

ad 3.) First of all I would avoid to let bundles randomly load system libraries. Maybe you can pack the handling of the system library and all of its access in a service bundle?

I agree, catching ERROR is not only scary, its probably not something we should do at all. Error is an VM error, and thats something which usually leads to a restart of your vm -or application in your case- to guarantee stable operation.

For me the check whether a library is available or not is similar to check whether a file resource exists or not. If libraries are something very dynamic in your application context you may either let the user browse for the library and let the application know where it is. If there is no such thing like a user, can't u simply search for the file in the path of the client machine?