org.springframework.osgi.io
Class OsgiBundleResource

java.lang.Object
  org.springframework.core.io.AbstractResource
      org.springframework.osgi.io.OsgiBundleResource

All Implemented Interfaces:

ContextResource, InputStreamSource, Resource

public class OsgiBundleResource
extends AbstractResource
implements ContextResource

Resource implementation for OSGi environments.

Lazy evaluation of the resource will be used. This implementation allows resource location inside:

• bundle space - if osgibundle:/BUNDLE_URL_PREFIX prefix is being used or none is specified. This space cotnains the bundle jar and its attached fragments.
• bundle jar - if osgibundlejar:/BUNDLE_JAR_URL_PREFIX is specified. This space contains just the bundle jar.
• class space - if ResourceUtils.CLASSPATH_URL_PREFIX is encountered. This space contains the bundle classpath, namely the bundle jar, its attached fragments and imported packages.

For more explanations on resource locations in OSGi, please see the Access to Resources chapter from the OSGi spec.

OSGi framework specific prefixes (such as bundleentry: and bundleresource:under Equinox, bundle: under Knopflefish and Felix, etc..) are supported. Resources outside the OSGi space (file:, http:, etc..) are supported as well as the path is being resolved to an URL.

If no prefix is specified, the bundle space will be used for locating a resource.

Note: When the bundle space (bundle jar and its attached fragments) is being searched, multiple URLs can be found but this implementation will return only the first one. Consider using OsgiBundleResourcePatternResolver to retrieve all entries.

Author:

Costin Leau, Adrian Colyer, Sam Brannen

Field Summary

static String	BUNDLE_JAR_URL_PREFIX Prefix for searching only the bundle raw jar.
static String	BUNDLE_URL_PREFIX Prefix for searching inside the owning bundle space.

Constructor Summary

OsgiBundleResource(Bundle bundle, String path)
Constructs a new OsgiBundleResource instance.

Method Summary

Resource	createRelative(String relativePath) Returns a resource relative to this resource.
boolean	equals(Object obj) This implementation compares the underlying bundle and path locations.
boolean	exists() Return whether this resource actually exists in physical form.
String	getDescription() This implementation returns a description that includes the bundle location.
File	getFile() Returns a File handle for this resource.
String	getFilename() Returns the filename of this resources.
InputStream	getInputStream() Returns an InputStream to this resource.
String	getPathWithinContext()
URL	getURL() Locates the resource in the underlying bundle based on the prefix, if it exists.
int	hashCode() This implementation returns the hash code of the underlying class path location.
long	lastModified()

Methods inherited from class org.springframework.core.io.AbstractResource

getFileForLastModifiedCheck, getURI, isOpen, isReadable, toString

Methods inherited from class java.lang.Object

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

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

getURI, isOpen, isReadable

Field Detail

BUNDLE_URL_PREFIX

public static final String BUNDLE_URL_PREFIX

Prefix for searching inside the owning bundle space. This translates to searching the bundle and its attached fragments. If no prefix is specified, this one will be used.

See Also:

Constant Field Values

BUNDLE_JAR_URL_PREFIX

public static final String BUNDLE_JAR_URL_PREFIX

Prefix for searching only the bundle raw jar. Will ignore attached fragments. Not used at the moment.

See Also:

Constant Field Values

Constructor Detail

OsgiBundleResource

public OsgiBundleResource(Bundle bundle,
                          String path)

Constructs a new OsgiBundleResource instance.

Parameters:

bundle - OSGi bundle used by this resource

path - resource path inside the bundle.

Method Detail

getInputStream

public InputStream getInputStream()
                           throws IOException

Returns an InputStream to this resource. This implementation opens an InputStream for the given URL. It sets the UseCaches flag to false, mainly to avoid jar file locking on Windows.

Specified by:

getInputStream in interface InputStreamSource

Returns:

input stream to the underlying resource

Throws:

IOException - if the stream could not be opened

See Also:

URL.openConnection(), URLConnection.setUseCaches(boolean), URLConnection.getInputStream()

getURL

public URL getURL()
           throws IOException

Locates the resource in the underlying bundle based on the prefix, if it exists. Note that the location happens per call since due to the dynamic nature of OSGi, the classpath of the bundle (among others) can change during a bundle lifecycle (depending on its imports).

Specified by:

getURL in interface Resource

Overrides:

getURL in class AbstractResource

Returns:

URL to this resource

Throws:

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

See Also:

Bundle.getEntry(String), Bundle.getResource(String)

createRelative

public Resource createRelative(String relativePath)

Returns a resource relative to this resource. This implementation creates an OsgiBundleResource, applying the given path relative to the path of the underlying resource of this descriptor.

Specified by:

createRelative in interface Resource

Overrides:

createRelative in class AbstractResource

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

See Also:

StringUtils.applyRelativePath(String, String)

getFilename

public String getFilename()

Returns the filename of this resources. This implementation returns the name of the file that this bundle path resource refers to.

Specified by:

getFilename in interface Resource

Overrides:

getFilename in class AbstractResource

Returns:

resource filename

See Also:

StringUtils.getFilename(String)

getFile

public File getFile()
             throws IOException

Returns a File handle for this resource. This method does a best-effort attempt to locate the bundle resource on the file system. It is strongly recommended to use getInputStream() method instead which works no matter if the bundles are saved (in exploded form or not) on the file system.

Specified by:

getFile in interface Resource

Overrides:

getFile in class AbstractResource

Returns:

File handle to 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

getDescription

public String getDescription()

This implementation returns a description that includes the bundle location.

Specified by:

getDescription in interface Resource

equals

public boolean equals(Object obj)

This implementation compares the underlying bundle and path locations.

Overrides:

equals in class AbstractResource

hashCode

public int hashCode()

This implementation returns the hash code of the underlying class path location.

Overrides:

hashCode in class AbstractResource

lastModified

public long lastModified()
                  throws IOException

Specified by:

lastModified in interface Resource

Overrides:

lastModified in class AbstractResource

Throws:

IOException

getPathWithinContext

public String getPathWithinContext()

Specified by:

getPathWithinContext in interface ContextResource

exists

public 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.

The existence check is done by opening an InputStream to the underlying resource (overriding the default implementation which checks first for the presence of a File).

Specified by:

exists in interface Resource

Overrides:

exists in class AbstractResource