spark.resource

Interface Resource

All Superinterfaces:

InputStreamResource

All Known Implementing Classes:

AbstractFileResolvingResource, AbstractResource, ClassPathResource, ExternalResource

public interface Resource
extends InputStreamResource

Interface for a resource descriptor that abstracts from the actual type of underlying resource, such as a file or class path resource.

An InputStream can be opened for every resource if it exists in physical form, but a URL or File handle can just be returned for certain resources. The actual behavior is implementation-specific.

Author:

Juergen Hoeller

See Also:

InputStreamResource.getInputStream(), getURL(), getURI(), getFile(), ClassPathResource, Code copied from Spring source. Modifications made (mostly removal of methods) by Per Wendel.

Method Summary

Modifier and Type	Method and Description
long	contentLength()
Resource	createRelative(String relativePath)
boolean	exists() Return whether this resource actually exists in physical form.
String	getDescription()
File	getFile()
String	getFilename() Determine a filename for this resource, i.e.
URI	getURI()
URL	getURL()
boolean	isOpen() Return whether this resource represents a handle with an open stream.
boolean	isReadable() Return whether the contents of this resource can be read, e.g.
long	lastModified()

Methods inherited from interface spark.resource.InputStreamResource

getInputStream

Method Detail

exists

boolean exists()

Return whether this resource actually exists in physical form.

This method performs a definitive existence check, whereas the existence of a Resource handle only guarantees a valid descriptor handle.

Returns:

if exists

isReadable

boolean isReadable()

Return whether the contents of this resource can be read, e.g. via InputStreamResource.getInputStream() or getFile().

Will be true for typical resource descriptors; note that actual content reading may still fail when attempted. However, a value of false is a definitive indication that the resource content cannot be read.

Returns:

if readable

See Also:

InputStreamResource.getInputStream()

isOpen

boolean isOpen()

Return whether this resource represents a handle with an open stream. If true, the InputStream cannot be read multiple times, and must be read and closed to avoid resource leaks.

Will be false for typical resource descriptors.

Returns:

if open

getURL

URL getURL()
    throws IOException

Returns:

a URL handle for this resource.

Throws:

IOException - if the resource cannot be resolved as URL, i.e. if the resource is not available as descriptor

getURI

URI getURI()
    throws IOException

Returns:

a URI handle for this resource.

Throws:

IOException - if the resource cannot be resolved as URI, i.e. if the resource is not available as descriptor

getFile

File getFile()
      throws IOException

Returns:

a File handle for this resource.

Throws:

IOException - if the resource cannot be resolved as absolute file path, i.e. if the resource is not available in a file system

contentLength

long contentLength()
            throws IOException

Returns:

the content length for this resource.

Throws:

IOException - if the resource cannot be resolved (in the file system or as some other known physical resource type)

lastModified

long lastModified()
           throws IOException

Returns:

the last-modified timestamp for this resource.

Throws:

IOException - if the resource cannot be resolved (in the file system or as some other known physical resource type)

createRelative

Resource createRelative(String relativePath)
                 throws IOException

Parameters:

relativePath - the relative path (relative to this resource)

Returns:

the resource handle for the relative resource

Throws:

IOException - if the relative resource cannot be determined

getFilename

String getFilename()

Determine a filename for this resource, i.e. typically the last part of the path: for example, "myfile.txt".

Returns null if this type of resource does not have a filename.

Returns:

the file name.

getDescription

String getDescription()

Returns:

a description for this resource, to be used for error output when working with the resource.

Implementations are also encouraged to return this value from their toString method.

See Also:

Object.toString()