code: public static URL getResource(Class<?> c, String resName) {
  		URL url = constructResourceURL(c, resName);
  
  		if (url == null)
  			return c.getResource(resName);
  
  		InputStream is = null;
  		try {
  			is = url.openStream();
  			is.read();
  		} catch (Exception e) {
  			return c.getResource(resName);
  		} finally {
  			try {
  				if (is != null)
  					is.close();
  			} catch (Exception e) {
  			}
  		}
  
  		return url;
  	}
docs: 定位资源。 首先查找指定类的加载路径，如果找不到，再由指定类的Class Loader从其CLASSPATH路径中查找。