public Resource createRelative(String relativePath) throws IOException 
{
		throw new FileNotFoundException("Cannot create a relative resource for " + getDescription());
}

This implementation throws a FileNotFoundException, assuming that relative resources cannot be created for this resource.

 public boolean equals(Object obj) 
{
		return (obj == this ||
		    (obj instanceof Resource && ((Resource) obj).getDescription().equals(getDescription())));
}

This implementation compares description strings.

 public boolean exists() 
{
		// Try file existence: can we find the file in the file system?
		try {
			return getFile().exists();
		}
		catch (IOException ex) {
			// Fall back to stream existence: can we open the stream?
			try {
				InputStream is = getInputStream();
				is.close();
				return true;
			}
			catch (Throwable isEx) {
				return false;
			}
		}
}

This implementation checks whether a File can be opened, falling back to whether an InputStream can be opened. This will cover both directories and content resources.

 public File getFile() throws IOException 
{
		throw new FileNotFoundException(getDescription() + " cannot be resolved to absolute file path");
}

This implementation throws a FileNotFoundException, assuming that the resource cannot be resolved to an absolute file path.

 protected File getFileForLastModifiedCheck() throws IOException 
{
		return getFile();
}

Determine the File to use for timestamp checking.

The default implementation delegates to #getFile() .

 public String getFilename() throws IllegalStateException 
{
		throw new IllegalStateException(getDescription() + " does not carry a filename");
}

This implementation always throws IllegalStateException, assuming that the resource does not carry a filename.

 public URI getURI() throws IOException 
{
		URL url = getURL();
		try {
			return ResourceUtils.toURI(url);
		}
		catch (URISyntaxException ex) {
			throw new NestedIOException("Invalid URI [" + url + "]", ex);
		}
}

This implementation builds a URI based on the URL returned by #getURL() .

 public URL getURL() throws IOException 
{
		throw new FileNotFoundException(getDescription() + " cannot be resolved to URL");
}

This implementation throws a FileNotFoundException, assuming that the resource cannot be resolved to a URL.

 public int hashCode() 
{
		return getDescription().hashCode();
}

This implementation returns the description's hash code.

 public boolean isOpen() 
{
		return false;
}

This implementation always returns false.

 public boolean isReadable() 
{
		return true;
}

This implementation always returns true.

 public long lastModified() throws IOException 
{
		long lastModified = getFileForLastModifiedCheck().lastModified();
		if (lastModified == 0L) {
			throw new FileNotFoundException(getDescription() +
					" cannot be resolved in the file system for resolving its last-modified timestamp");
		}
		return lastModified;
}

This implementation checks the timestamp of the underlying File, if available.

 public String toString() 
{
		return getDescription();
}

This implementation returns the description of this resource.