org.springframework.core.io

Interface Resource

All Superinterfaces:

InputStreamSource

All Known Subinterfaces:

ContextResource, HttpResource, HttpResource, WritableResource

All Known Implementing Classes:

AbstractFileResolvingResource, AbstractResource, ByteArrayResource, ClassPathResource, DefaultResourceLoader.ClassPathContextResource, DescriptiveResource, FileSystemResource, FileUrlResource, InputStreamResource, PathResource, ServletContextResource, TransformedResource, TransformedResource, UrlResource, VfsResource

public interface Resource
extends InputStreamSource

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.

Since:

28.12.2003

Author:

Juergen Hoeller

See Also:

InputStreamSource.getInputStream(), getURL(), getURI(), getFile(), WritableResource, ContextResource, UrlResource, FileUrlResource, FileSystemResource, ClassPathResource, ByteArrayResource, InputStreamResource

Method Summary

Modifier and Type	Method and Description
long	contentLength() Determine the content length for this resource.
Resource	createRelative(String relativePath) Create a resource relative to this resource.
boolean	exists() Determine whether this resource actually exists in physical form.
String	getDescription() Return a description for this resource, to be used for error output when working with the resource.
File	getFile() Return a File handle for this resource.
String	getFilename() Determine a filename for this resource, i.e.
URI	getURI() Return a URI handle for this resource.
URL	getURL() Return a URL handle for this resource.
default boolean	isFile() Determine whether this resource represents a file in a file system.
default boolean	isOpen() Indicate whether this resource represents a handle with an open stream.
default boolean	isReadable() Indicate whether non-empty contents of this resource can be read via InputStreamSource.getInputStream().
long	lastModified() Determine the last-modified timestamp for this resource.
default ReadableByteChannel	readableChannel() Return a ReadableByteChannel.

Methods inherited from interface org.springframework.core.io.InputStreamSource

getInputStream

Method Detail

exists

boolean exists()

Determine 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.

isReadable

default boolean isReadable()

Indicate whether non-empty contents of this resource can be read via InputStreamSource.getInputStream().

Will be true for typical resource descriptors that exist since it strictly implies exists() semantics as of 5.1. 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.

See Also:

InputStreamSource.getInputStream(), exists()

isOpen

default boolean isOpen()

Indicate 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.

isFile

default boolean isFile()

Determine whether this resource represents a file in a file system. A value of true strongly suggests (but does not guarantee) that a getFile() call will succeed.

This is conservatively false by default.

Since:

5.0

See Also:

getFile()

getURL

URL getURL()
    throws IOException

Return 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

Return 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

Since:

2.5

getFile

File getFile()
      throws IOException

Return a File handle for this resource.

Throws:

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

IOException - in case of general resolution/reading failures

See Also:

InputStreamSource.getInputStream()

readableChannel

default ReadableByteChannel readableChannel()
                                     throws IOException

Return a ReadableByteChannel.

It is expected that each call creates a fresh channel.

The default implementation returns Channels.newChannel(InputStream) with the result of InputStreamSource.getInputStream().

Returns:

the byte channel for the underlying resource (must not be null)

Throws:

FileNotFoundException - if the underlying resource doesn't exist

IOException - if the content channel could not be opened

Since:

5.0

See Also:

InputStreamSource.getInputStream()

contentLength

long contentLength()
            throws IOException

Determine 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

Determine 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

Create a resource relative to this resource.

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

@Nullable
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.

getDescription

String getDescription()

Return 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()