org.springframework.core.io

Class AbstractResource

java.lang.Object

org.springframework.core.io.AbstractResource

All Implemented Interfaces:

InputStreamSource, Resource

Direct Known Subclasses:

AbstractFileResolvingResource, ByteArrayResource, DescriptiveResource, FileSystemResource, InputStreamResource, PathResource, VfsResource

public abstract class AbstractResource
extends Object
implements Resource

Convenience base class for Resource implementations, pre-implementing typical behavior.

The "exists" method will check whether a File or InputStream can be opened; "isOpen" will always return false; "getURL" and "getFile" throw an exception; and "toString" will return the description.

Since:

28.12.2003

Author:

Juergen Hoeller, Sam Brannen

Constructor Summary

Constructors

Constructor and Description
AbstractResource()

Method Summary

Modifier and Type	Method and Description
long	contentLength() This method reads the entire InputStream to determine the content length.
Resource	createRelative(String relativePath) This implementation throws a FileNotFoundException, assuming that relative resources cannot be created for this resource.
boolean	equals(Object other) This implementation compares description strings.
boolean	exists() This implementation checks whether a File can be opened, falling back to whether an InputStream can be opened.
File	getFile() This implementation throws a FileNotFoundException, assuming that the resource cannot be resolved to an absolute file path.
protected File	getFileForLastModifiedCheck() Determine the File to use for timestamp checking.
String	getFilename() This implementation always returns null, assuming that this resource type does not have a filename.
URI	getURI() This implementation builds a URI based on the URL returned by getURL().
URL	getURL() This implementation throws a FileNotFoundException, assuming that the resource cannot be resolved to a URL.
int	hashCode() This implementation returns the description's hash code.
boolean	isFile() This implementation always returns false.
boolean	isOpen() This implementation always returns false.
boolean	isReadable() This implementation always returns true for a resource that exists (revised as of 5.1).
long	lastModified() This implementation checks the timestamp of the underlying File, if available.
ReadableByteChannel	readableChannel() This implementation returns Channels.newChannel(InputStream) with the result of InputStreamSource.getInputStream().
String	toString() This implementation returns the description of this resource.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

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

getDescription

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

getInputStream

Constructor Detail

AbstractResource

public AbstractResource()

Method Detail

exists

public boolean exists()

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.

Specified by:

exists in interface Resource

isReadable

public boolean isReadable()

This implementation always returns true for a resource that exists (revised as of 5.1).

Specified by:

isReadable in interface Resource

See Also:

InputStreamSource.getInputStream(), Resource.exists()

isOpen

public boolean isOpen()

This implementation always returns false.

Specified by:

isOpen in interface Resource

isFile

public boolean isFile()

This implementation always returns false.

Specified by:

isFile in interface Resource

See Also:

Resource.getFile()

getURL

public URL getURL()
           throws IOException

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

Specified by:

getURL in interface Resource

Throws:

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

getURI

public URI getURI()
           throws IOException

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

Specified by:

getURI in interface Resource

Throws:

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

getFile

public File getFile()
             throws IOException

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

Specified by:

getFile in interface 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

public ReadableByteChannel readableChannel()
                                    throws IOException

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

This is the same as in Resource's corresponding default method but mirrored here for efficient JVM-level dispatching in a class hierarchy.

Specified by:

readableChannel in interface Resource

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

See Also:

InputStreamSource.getInputStream()

contentLength

public long contentLength()
                   throws IOException

This method reads the entire InputStream to determine the content length.

For a custom sub-class of InputStreamResource, we strongly recommend overriding this method with a more optimal implementation, e.g. checking File length, or possibly simply returning -1 if the stream can only be read once.

Specified by:

contentLength in interface Resource

Throws:

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

See Also:

InputStreamSource.getInputStream()

lastModified

public long lastModified()
                  throws IOException

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

Specified by:

lastModified in interface Resource

Throws:

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

See Also:

getFileForLastModifiedCheck()

getFileForLastModifiedCheck

protected File getFileForLastModifiedCheck()
                                    throws IOException

Determine the File to use for timestamp checking.

The default implementation delegates to getFile().

Returns:

the File to use for timestamp checking (never null)

Throws:

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

IOException - in case of general resolution/reading failures

createRelative

public Resource createRelative(String relativePath)
                        throws IOException

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

Specified by:

createRelative in interface 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
public String getFilename()

This implementation always returns null, assuming that this resource type does not have a filename.

Specified by:

getFilename in interface Resource

equals

public boolean equals(@Nullable
                      Object other)

This implementation compares description strings.

Overrides:

equals in class Object

See Also:

Resource.getDescription()

hashCode

public int hashCode()

This implementation returns the description's hash code.

Overrides:

hashCode in class Object

See Also:

Resource.getDescription()

toString

public String toString()

This implementation returns the description of this resource.

Overrides:

toString in class Object

See Also:

Resource.getDescription()