Added static helper methods for getting the underlying NativeLibrary instance from a Library interface instance or from a "registered" class.

CHANGES.md

@@ -11,6 +11,7 @@ Features
 * [#1593](https://github.com/java-native-access/jna/pull/1593): Add support for DragonFly BSD x86-64 - [@liweitianux](https://github.com/liweitianux).
 * [#1595](https://github.com/java-native-access/jna/pull/1595): Add `IsProcessorFeaturePresent` to `c.s.j.p.win32.Kernel32` - [@dbwiddis](https://github.com/dbwiddis).
 * [#1602](https://github.com/java-native-access/jna/pull/1602): Add `XMoveWindow`, `XResizeWindow`, `XMoveResizeWindow`, `XRaiseWindow`, `XLowerWindow` X11 calls to `c.s.j.p.unix.X11` - [@vinceh121](https://github.com/vinceh121).
+* [#1612](https://github.com/java-native-access/jna/pull/1612): Added static helper methods for getting the underlying NativeLibrary instance from a Library interface instance or from a "registered" class.
 
 Bug Fixes
 ---------

src/com/sun/jna/Library.java

@@ -271,4 +271,17 @@ public Object invoke(Object proxy, Method method, Object[] inArgs)
             }
         }
     }
+
+    /**
+     * Get the {@link NativeLibrary} instance that is wrapped by the given {@link Library} interface instance.
+     * @param library the {@link Library} interface instance, which was created by the {@link Native#load Native.load()} method
+     * @return the wrapped {@link NativeLibrary} instance
+     */
+    static NativeLibrary getNativeLibrary(final Library library) {
+        final InvocationHandler handler = Proxy.getInvocationHandler(library);
+        if (!(handler instanceof Handler)) {
+            throw new IllegalArgumentException("Object is not a properly initialized Library interface instance");
+        }
+        return ((Handler)handler).getNativeLibrary();
+    }
 }

src/com/sun/jna/Native.java

@@ -1918,6 +1918,23 @@ public static void register(Class<?> cls, NativeLibrary lib) {
         }
     }
 
+    /**
+     * Get the {@link NativeLibrary} instance to which the given "registered" class is bound.
+     * @param cls the "registered" class, which was previously registered via the {@link Native#register register()} method
+     * @return the {@link NativeLibrary} instance to which the "registered" class is bound
+     */
+    public static NativeLibrary getNativeLibrary(final Class<?> cls) {
+        final Class<?> mappedClass = findDirectMappedClass(cls);
+        synchronized(registeredClasses) {
+            final NativeLibrary nativeLibrary = registeredLibraries.get(mappedClass);
+            if (nativeLibrary == null) {
+                throw new IllegalArgumentException("Class " + cls.getName() + " is not currently registered");
+            } else {
+                return nativeLibrary;
+            }
+        }
+    }
+
     /* Take note of options used for a given library mapping, to facilitate
      * looking them up later.
      */