org.crosswire.common.util
Class NetUtil

java.lang.Object
  org.crosswire.common.util.NetUtil

public class NetUtil
extends Object

The NetUtil class looks after general utility stuff around the java.net package.

Distribution Licence:
JSword is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License, version 2 as published by the Free Software Foundation.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
The License is available on the internet here, or by writing to: Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
The copyright to this program is held by it's authors.

Author:

Joe Walker [joe at eireneh dot com], Mark Goodwin

See Also:

Licence

Nested Class Summary

static class	NetUtil.IsDirectoryURLFilter Check that the directories in the version directory really represent versions.
static class	NetUtil.URLFilterFilenameFilter Quick implementation of FilenameFilter that uses a URLFilter

Field Summary

static String	AUTH_SEPERATOR_PASSWORD Separating the password from the username
static String	AUTH_SEPERATOR_USERNAME Separating the username from the rest of the URL
private static File	cachedir Where are temporary files cached.
static String	INDEX_FILE For directory listings
private static Logger	log The log stream
static String	PROTOCOL_FILE Constant for the file: protocol
static String	PROTOCOL_FTP Constant for the file: protocol
static String	PROTOCOL_HTTP Constant for the file: protocol
static String	PROTOCOL_JAR Constant for the jar: protocol
static String	SEPARATOR URL separator
private static String	TEMP_SUFFIX The temporary suffix, used when a temporary file is needed in the system's temporary directory.

Constructor Summary

private

NetUtil() Basic constructor - ensure that we can't be instansiated

Method Summary

private static void	checkFileURL(URL url) Throw if the given URL does not use the 'file:' protocol
static boolean	delete(URL orig) Delete a URL.
static File	getAsFile(URL url) Return a File from the URL either by extracting from a file: URL or by downloading to a temp dir first
static long	getLastModified(URL url) When was the given URL last modified.
static OutputStream	getOutputStream(URL url) Attempt to obtain an OutputStream from a URL.
static OutputStream	getOutputStream(URL url, boolean append) Attempt to obtain an OutputStream from a URL.
static int	getSize(URL url)
static URL	getTemporaryURL(String prefix, String suffix) A URL version of File.createTempFile()
static URL	getURL(File file) Get a URL version of the given file.
static File	getURLCacheDir() Returns the URLCacheDir.
static boolean	isDirectory(URL orig) If there is a directory at the other end of this URL return true.
static boolean	isFile(URL url) If there is a file at the other end of this URL return true.
static boolean	isNewer(URL left, URL right) Returns whether the left is newer than the right by comparing their last modified dates.
private static boolean	isSeparator(char c)
static URL	lengthenURL(URL orig, String extra) Utility to add a string to the end of a URL.
static String[]	list(URL url, URLFilter filter) List the items available assuming that this URL points to a directory.
static String[]	listByFile(URL url, URLFilter filter) List all the files specified by the index file passed in.
static String[]	listByIndexFile(URL index, URLFilter filter) List all the files specified by the index file passed in.
static void	makeDirectory(URL orig) If the directory does not exist, create it.
static void	makeFile(URL orig) If the file does not exist, create it.
static boolean	move(URL oldUrl, URL newUrl) Move a URL from one place to another.
static void	setURLCacheDir(File cachedir) Sets the cache directory.
static URL	shortenURL(URL orig, String strip) Utility to strip a string from the end of a URL.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

PROTOCOL_FILE

public static final String PROTOCOL_FILE

Constant for the file: protocol

See Also:

Constant Field Values

PROTOCOL_HTTP

public static final String PROTOCOL_HTTP

Constant for the file: protocol

See Also:

Constant Field Values

PROTOCOL_FTP

public static final String PROTOCOL_FTP

Constant for the file: protocol

See Also:

Constant Field Values

PROTOCOL_JAR

public static final String PROTOCOL_JAR

Constant for the jar: protocol

See Also:

Constant Field Values

INDEX_FILE

public static final String INDEX_FILE

For directory listings

See Also:

Constant Field Values

SEPARATOR

public static final String SEPARATOR

URL separator

See Also:

Constant Field Values

AUTH_SEPERATOR_USERNAME

public static final String AUTH_SEPERATOR_USERNAME

Separating the username from the rest of the URL

See Also:

Constant Field Values

AUTH_SEPERATOR_PASSWORD

public static final String AUTH_SEPERATOR_PASSWORD

Separating the password from the username

See Also:

Constant Field Values

TEMP_SUFFIX

private static final String TEMP_SUFFIX

The temporary suffix, used when a temporary file is needed in the system's temporary directory.

See Also:

Constant Field Values

cachedir

private static File cachedir

Where are temporary files cached.

log

private static final Logger log

The log stream

Constructor Detail

NetUtil

private NetUtil()

Basic constructor - ensure that we can't be instansiated

Method Detail

makeDirectory

public static void makeDirectory(URL orig)
                          throws MalformedURLException

If the directory does not exist, create it. Note this currently only works with file: type URLs

Parameters:

orig - The URL to check

Throws:

MalformedURLException

makeFile

public static void makeFile(URL orig)
                     throws MalformedURLException,
                            IOException

If the file does not exist, create it. Note this currently only works with file: type URLs

Parameters:

orig - The URL to check

Throws:

MalformedURLException

IOException

isFile

public static boolean isFile(URL url)

If there is a file at the other end of this URL return true. Note this currently only works with file: type URLs

Parameters:

url - The URL to check

Returns:

true if the URL points at a file

isDirectory

public static boolean isDirectory(URL orig)

If there is a directory at the other end of this URL return true. Note non file: type URLs will always return false

Parameters:

orig - The URL to check

Returns:

true if the URL points at a file: directory

move

public static boolean move(URL oldUrl,
                           URL newUrl)
                    throws IOException

Move a URL from one place to another. Currently this only works for file: URLs, however the interface should not need to change to handle more complex URLs

Parameters:

oldUrl - The URL to move

newUrl - The desitination URL

Throws:

IOException

delete

public static boolean delete(URL orig)
                      throws IOException

Delete a URL. Currently this only works for file: URLs, however the interface should not need to change to handle more complex URLs

Parameters:

orig - The URL to delete

Throws:

IOException

getAsFile

public static File getAsFile(URL url)
                      throws IOException

Return a File from the URL either by extracting from a file: URL or by downloading to a temp dir first

Parameters:

url - The original URL to the file.

Returns:

The URL as a file

Throws:

IOException

shortenURL

public static URL shortenURL(URL orig,
                             String strip)
                      throws MalformedURLException

Utility to strip a string from the end of a URL.

Parameters:

orig - The URL to strip

strip - The text to strip from the end of the URL

Returns:

The stripped URL

Throws:

MalformedURLException - If the URL does not end in the given text

lengthenURL

public static URL lengthenURL(URL orig,
                              String extra)

Utility to add a string to the end of a URL.

Parameters:

orig - The URL to strip

extra - The text to add to the end of the URL

Returns:

The stripped URL

isSeparator

private static boolean isSeparator(char c)

getOutputStream

public static OutputStream getOutputStream(URL url)
                                    throws IOException

Attempt to obtain an OutputStream from a URL. The simple case will just call url.openConnection().getOutputStream(), however in some JVMs (MS at least this fails where new FileOutputStream(url) works. So if openConnection().getOutputStream() fails and the protocol is file, then the alternate version is used.

Parameters:

url - The URL to attempt to write to

Returns:

An OutputStream connection

Throws:

IOException

getOutputStream

public static OutputStream getOutputStream(URL url,
                                           boolean append)
                                    throws IOException

Attempt to obtain an OutputStream from a URL. The simple case will just call url.openConnection().getOutputStream(), however in some JVMs (MS at least this fails where new FileOutputStream(url) works. So if openConnection().getOutputStream() fails and the protocol is file, then the alternate version is used.

Parameters:

url - The URL to attempt to write to

append - Do we write to the end of the file instead of the beginning

Returns:

An OutputStream connection

Throws:

IOException

list

public static String[] list(URL url,
                            URLFilter filter)
                     throws MalformedURLException,
                            IOException

List the items available assuming that this URL points to a directory.

There are 2 methods of calculating the answer - if the URL is a file: URL then we can just use File.list(), otherwise we ask for a file inside the directory called index.txt and assume the directories contents to be listed one per line.

If the URL is a file: URL then we execute both methods and warn if there is a difference, but returning the values from the index.txt method.

Throws:

MalformedURLException

IOException

listByFile

public static String[] listByFile(URL url,
                                  URLFilter filter)
                           throws MalformedURLException

List all the files specified by the index file passed in.

Returns:

String[] Matching results.

Throws:

MalformedURLException

listByIndexFile

public static String[] listByIndexFile(URL index,
                                       URLFilter filter)
                                throws IOException

List all the files specified by the index file passed in.

Returns:

String[] Matching results.

Throws:

IOException

getSize

public static int getSize(URL url)

Parameters:

url - the resource whose size is wanted

Returns:

the size of that resource

getLastModified

public static long getLastModified(URL url)

When was the given URL last modified. If no modification time is available then this method return the current time.

isNewer

public static boolean isNewer(URL left,
                              URL right)

Returns whether the left is newer than the right by comparing their last modified dates.

Parameters:

left -

right -

Returns:

true if the left is newer

checkFileURL

private static void checkFileURL(URL url)
                          throws MalformedURLException

Throw if the given URL does not use the 'file:' protocol

Parameters:

url - The URL to check

Throws:

MalformedURLException - If the protocol is not file:

getURLCacheDir

public static File getURLCacheDir()

Returns the URLCacheDir.

Returns:

File

setURLCacheDir

public static void setURLCacheDir(File cachedir)

Sets the cache directory.

Parameters:

cachedir - The URLCacheDir to set

getURL

public static URL getURL(File file)

Get a URL version of the given file.

Parameters:

file - The File to turn into a URL

Returns:

a URL for the given file

getTemporaryURL

public static URL getTemporaryURL(String prefix,
                                  String suffix)
                           throws IOException

A URL version of File.createTempFile()

Returns:

A new temporary URL

Throws:

IOException - If something goes wrong creating the temp URL