Spring Framework

org.springframework.core.io
Interface Resource

All Superinterfaces:
InputStreamSource
All Known Subinterfaces:
ContextResource, WritableResource
All Known Implementing Classes:
AbstractFileResolvingResource, AbstractResource, ByteArrayResource, ClassPathResource, DescriptiveResource, FileSystemResource, InputStreamResource, PortletContextResource, ServletContextResource, 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:
getInputStream(), getURL(), getURI(), getFile(), WritableResource, ContextResource, FileSystemResource, ClassPathResource, UrlResource, ByteArrayResource, InputStreamResource

Method Summary
 long contentLength()
          Determine the content length for this resource.
 Resource createRelative(java.lang.String relativePath)
          Create a resource relative to this resource.
 boolean exists()
          Return whether this resource actually exists in physical form.
 java.lang.String getDescription()
          Return a description for this resource, to be used for error output when working with the resource.
 java.io.File getFile()
          Return a File handle for this resource.
 java.lang.String getFilename()
          Determine a filename for this resource, i.e.
 java.io.InputStream getInputStream()
          Return an InputStream.
 java.net.URI getURI()
          Return a URI handle for this resource.
 java.net.URL getURL()
          Return a URL handle for this resource.
 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()
          Determine the last-modified timestamp for this resource.
 

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.


isReadable

boolean isReadable()
Return whether the contents of this resource can be read, e.g. via 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.

See Also:
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.


getURL

java.net.URL getURL()
                    throws java.io.IOException
Return a URL handle for this resource.

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

getURI

java.net.URI getURI()
                    throws java.io.IOException
Return a URI handle for this resource.

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

getFile

java.io.File getFile()
                     throws java.io.IOException
Return a File handle for this resource.

Throws:
java.io.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 java.io.IOException
Determine the content length for this resource.

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

lastModified

long lastModified()
                  throws java.io.IOException
Determine the last-modified timestamp for this resource.

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

createRelative

Resource createRelative(java.lang.String relativePath)
                        throws java.io.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:
java.io.IOException - if the relative resource cannot be determined

getFilename

java.lang.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

java.lang.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()

getInputStream

java.io.InputStream getInputStream()
                                   throws java.io.IOException
Return an InputStream.

It is expected that each call creates a fresh stream.

This requirement is particularly important when you consider an API such as JavaMail, which needs to be able to read the stream multiple times when creating mail attachments. For such a use case, it is required that each getInputStream() call returns a fresh stream.

Specified by:
getInputStream in interface InputStreamSource
Returns:
the input stream for the underlying resource (must not be null).
Throws:
java.io.IOException - if the stream could not be opened
See Also:
MimeMessageHelper.addAttachment(String, InputStreamSource)

Spring Framework