code: public static File getCacheDir ()
      {
          if (_tmpdir == null) {
              String tmpdir = System.getProperty("java.io.tmpdir");
              if (tmpdir == null) {
                  log.info("No system defined temp directory. Faking it.");
                  tmpdir = System.getProperty("user.home");
              }
              setCacheDir(new File(tmpdir));
          }
          return _tmpdir;
      }
docs: Returns the cache directory used for unpacked resources.