net.sf.mmm.util.resource.base

Class UrlResource

java.lang.Object

net.sf.mmm.util.resource.base.AbstractDataResource

net.sf.mmm.util.resource.base.UrlResource

All Implemented Interfaces:

DataResource

public class UrlResource
extends AbstractDataResource

This is the implementation of the DataResource interface for a resource that comes from an URL.

Since:

1.0.2

Author:

Joerg Hohwiller (hohwille at users.sourceforge.net)

Field Summary

Fields

Modifier and Type	Field and Description
private FileUtilLimited	fileUtil The FileUtilLimited instance.
static String	SCHEME_PREFIX_FTP The scheme-prefix for FTP.
static String	SCHEME_PREFIX_HTTP The scheme-prefix for HTTP.
static String	SCHEME_PREFIX_HTTPS The scheme-prefix for HTTPS.
private URL	url

Constructor Summary

Constructors

Constructor and Description
UrlResource(String url) The constructor.
UrlResource(String absolutePath, FileUtilLimited fileUtil) The constructor.
UrlResource(URL url) The constructor.
UrlResource(URL url, FileUtilLimited fileUtil) The constructor.

Method Summary

Modifier and Type	Method and Description
Date	getLastModificationDate() This method gets the last modification date of the DataResource if available and supported.
String	getName() This method gets the name of the resource.
String	getPath() This method gets the path of this resource.
String	getSchemePrefix() This method gets the scheme-prefix of absolute URIs for this type of DataResource.
URL	getUrl() This method gets this resource as URL.
boolean	isAvailable() This method determines if this resource is available.
boolean	isData() This method determines if this resource has potentially data available.
DataResource	navigate(String relativePath) This method retrieves a DataResource pointing to the given resourcePath based on this resource. E.g.

Methods inherited from class net.sf.mmm.util.resource.base.AbstractDataResource

equals, getSize, getUri, hashCode, isModifiedSince, openOutputStream, openStream, toString

Methods inherited from class java.lang.Object

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

Field Detail

SCHEME_PREFIX_HTTP

public static final String SCHEME_PREFIX_HTTP

The scheme-prefix for HTTP.

See Also:

Constant Field Values

SCHEME_PREFIX_HTTPS

public static final String SCHEME_PREFIX_HTTPS

The scheme-prefix for HTTPS.

See Also:

Constant Field Values

SCHEME_PREFIX_FTP

public static final String SCHEME_PREFIX_FTP

The scheme-prefix for FTP.

See Also:

Constant Field Values

url

private final URL url

See Also:

getUrl()

fileUtil

private final FileUtilLimited fileUtil

The FileUtilLimited instance.

Constructor Detail

UrlResource

public UrlResource(String url)

The constructor.

Parameters:

url - is the URL to the resource. E.g. "http://foo.bar/index.html".

UrlResource

public UrlResource(String absolutePath,
                   FileUtilLimited fileUtil)

The constructor.

Parameters:

absolutePath - is the absolute path to the resource. E.g. "http://foo.bar/index.html".

fileUtil - is the FileUtilLimited to use.

UrlResource

public UrlResource(URL url)

The constructor.

Parameters:

url - is the URL.

UrlResource

public UrlResource(URL url,
                   FileUtilLimited fileUtil)

The constructor.

Parameters:

url - is the URL.

fileUtil - is the FileUtilLimited to use.

Method Detail

getLastModificationDate

public Date getLastModificationDate()

This method gets the last modification date of the DataResource if available and supported.

Returns:

the last modification Date or null if not available or supported.

getSchemePrefix

public String getSchemePrefix()

This method gets the scheme-prefix of absolute URIs for this type of DataResource. The scheme-prefix has the following form: <scheme>:<suffix> where <suffix> is the empty string or something like //.

Specified by:

getSchemePrefix in class AbstractDataResource

Returns:

the scheme-prefix of this resource.

isAvailable

public boolean isAvailable()

This method determines if this resource is available. Available simply means that it exists and data can be read.
ATTENTION:
Depending on the underlying implementation this can be a relatively expensive operation. E.g. if this resource points to a remote URL this method has to open a network connection in order to verify if the resource is available. Use DataResource.isData() to prevent such expensive operaitons.

Specified by:

isAvailable in interface DataResource

Overrides:

isAvailable in class AbstractDataResource

Returns:

true if this resource is available, false otherwise.

isData

public boolean isData()

This method determines if this resource has potentially data available. Unlike DataResource.isAvailable() this method will not invoke expensive operations like connecting to remote URLs. If this method will return false, then DataResource.isAvailable() would also have returned false. However in case of true only DataResource.isAvailable() can guarantee if a resource really exists and contains data. E.g. if the resource points to a File then this method can check if it is a data-file. So in case it points to a directory or does not exist at all in the filesystem, this method will return false. Please also note that this may invoke expensive operations if the according directory path points to something like a network share. You should also be aware that the state of DataResource.isData() and DataResource.isAvailable() can change at any time so you never have a full guarantee if some data exists or NOT. However in most cases it is very improbable that this status changes when you read the resource immediately after the check.

Returns:

true if this resource points to potential data, false otherwise.

getPath

public String getPath()

This method gets the path of this resource. Please note that the path is including the name of the resource.
ATTENTION:
The result of this method may differ to the path used in the URL when this resource has been created.

Specified by:

getPath in interface DataResource

Overrides:

getPath in class AbstractDataResource

Returns:

the path that was used to identify this resource when creating.

getUrl

public URL getUrl()
           throws ResourceNotAvailableException

This method gets this resource as URL.

Returns:

the URL that represents this resource.

Throws:

ResourceNotAvailableException - if an URL can NOT be created because the represented resource does not exist.

getName

public String getName()

This method gets the name of the resource. It is analog to a filename.

Specified by:

getName in interface DataResource

Overrides:

getName in class AbstractDataResource

Returns:

the name of the resource.

navigate

public DataResource navigate(String relativePath)

This method retrieves a DataResource pointing to the given resourcePath based on this resource.
E.g. if this resource points to the file "/etc/init.d/rc" and resourcePath would be "../apt/sources.list" the resulting resource would point to "/etc/apt/sources.list".
ATTENTION:
As you can see by the example above this method always navigates relative to the parent folder of this resource. This will also be the case if this resource itself is a folder. Due to this generic API this is the only consistent way as there are implementations that can not easily know if they represent a folder or a file or maybe even both at the same time. However, please be aware of this and do not get confused as you might expect this to be a cd command if invoked on a folder what is not exactly not the case (instead it is a cd on the parent folder).

Parameters:

relativePath - is the absolute or relative path pointing to a new resource. If it is a relative path, it is interpreted relative to the parent URI (directory) of this resource.

Returns:

is the resource pointing to the given path (relative to this resource).