diff -ur jna-3.0.4-svn630/src/com/sun/jna/CallbackReference.java jna-3.0.4-svn630.orig/src/com/sun/jna/CallbackReference.java
--- jna-3.0.4-svn630/src/com/sun/jna/CallbackReference.java	2008-07-31 13:44:21.000000000 -0400
+++ jna-3.0.4-svn630.orig/src/com/sun/jna/CallbackReference.java	2008-09-03 09:04:35.000000000 -0400
@@ -16,6 +16,7 @@
 import java.lang.reflect.InvocationHandler;
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
+import java.lang.reflect.Field;
 import java.lang.reflect.Proxy;
 import java.util.HashMap;
 import java.util.Iterator;
@@ -150,22 +151,45 @@
         }
         return cls;
     }
+
+    private static Method checkMethod(Method m) {
+	if (m.getParameterTypes().length > Function.MAX_NARGS) {
+	    String msg = "Method signature exceeds the maximum "
+		+ "parameter count: " + m;
+	    throw new IllegalArgumentException(msg);
+	}
+	return m;
+    }
     
     private static Method getCallbackMethod(Callback callback) {
-        Method[] mlist = callback.getClass().getMethods();
+        Class klass = callback.getClass();
+        Method[] mlist = klass.getDeclaredMethods();
+
+	/* If there's only one method, just try it. */
+	if (mlist.length == 1)
+	    return checkMethod(mlist[0]);
+
+	/* Now try looking for a field named "METHOD_NAME" which
+	 * tells us which method to use.
+	 */
+	String methName = Callback.METHOD_NAME;
+	try {
+	    Field methNameField = klass.getField("METHOD_NAME");
+	    methName = (String) methNameField.get(null);
+        } catch (NoSuchFieldException e) { 
+        } catch (Exception e) {
+	    String msg = "Callback METHOD_NAME field is invalid";
+	    throw new IllegalArgumentException(msg);
+        }
+
         for (int mi=0;mi < mlist.length;mi++) {
             Method m = mlist[mi];
-            if (Callback.METHOD_NAME.equals(m.getName())) {
-                if (m.getParameterTypes().length > Function.MAX_NARGS) {
-                    String msg = "Method signature exceeds the maximum "
-                        + "parameter count: " + m;
-                    throw new IllegalArgumentException(msg);
-                }
-                return m;
+            if (methName.equals(m.getName())) {
+		return checkMethod(m);
             }
         }
         String msg = "Callback must implement method named '"
-            + Callback.METHOD_NAME + "'";
+            + methName + "'";
         throw new IllegalArgumentException(msg);
     }