Small fix for the Cache Monitor when using proxyCacheLayout=hash

see: http://www.yacy-forum.de/viewtopic.php?p=27394#27394



git-svn-id: https://svn.berlios.de/svnroot/repos/yacy/trunk@2916 6c8d7289-2bf4-0310-a012-ef5d649a1542

source/de/anomic/plasma/plasmaHTCache.java

@@ -712,7 +712,7 @@ public final class plasmaHTCache {
      * This is a helper funktion that extracts the Hash from the filename
      */
     public static String getHash(final File f) {
-        if ((f.getPath().indexOf("hash")) < 0) return null;
+        if ((!f.isFile()) || (f.getPath().indexOf("hash") < 0)) return null;
         String hexHash = f.getName().substring(0,18);
         if (hexHash.indexOf('.') >= 0) return null;
         try {