info.monitorenter.util
Class FileUtil

java.lang.Object
  info.monitorenter.util.FileUtil

public final class FileUtil
extends Object

Utility class for file operations.

For methods that are not static get the singleton instance via getInstance().

Version:

1.1

Author:

Achim Westermann

Method Summary

static Map.Entry	cutDirectoryInformation(String path) Cuts the path information of the String that is interpreted as a filename into the directory part and the file part.
static Map.Entry	cutDirectoryInformation(URL path) Cuts all path information of the String representation of the given URL.
static Map.Entry	cutExtension(String filename) Cuts a String into the part before the last dot and after the last dot.
String	formatFilesize(long filesize, Locale locale) Returns the formatted filesize to Bytes, KB, MB or GB depending on the given value.
static String	getDefaultFileName(String name) Finds a filename based on the given name.
static FileUtil	getInstance() Returns the singleton instance of this class.
static boolean	isAllASCII(File f) Tests wether the given file only contains ASCII characters if interpreted by reading bytes (16 bit).
static boolean	isAllASCII(InputStream in) Tests wether the given input stream only contains ASCII characters if interpreted by reading bytes (16 bit).
static boolean	isEqual(File document, Charset a, Charset b) Tests, wether the content of the given file is identical at character level, when it is opened with both different Charsets.
static InputStream	readCache(File f) Invokes readRAM(File), but decorates the result with a ByteArrayInputStream.
static byte[]	readRAM(File f) Reads the content of the given File into an array.
static void	removeDuplicateLineBreaks(File f) Removes the duplicate line breaks in the given file.

Methods inherited from class java.lang.Object

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

Method Detail

cutDirectoryInformation

public static Map.Entry cutDirectoryInformation(URL path)

Cuts all path information of the String representation of the given URL.

   
  "file//c:/work/programming/anyfile.jar" --> "anyfile.jar"
  "http://jamwg.de"                       --> "" // No file part.
  "ftp://files.com/directory2/"           --> "" // File part of URL denotes a directory.
    
 

Assuming, that '/' is the current file separator character.

Parameters:

path - the absolute file path you want the mere file name of.

Returns:

the Map.Entry consisting of path information and file name.

cutDirectoryInformation

public static Map.Entry cutDirectoryInformation(String path)

Cuts the path information of the String that is interpreted as a filename into the directory part and the file part. The current operating system's path separator is used to cut all path information from the String.

   
  "c:/work/programming/anyfile.jar" --> Map.Entry("c:/work/programming/","anyfile.jar");
  "anyfile.jar"                     --> Map.Entry(new File(".").getAbsolutePath(),"anyfile.jar");
  "c:/directory1/directory2/"       --> Map.Entry("c:/directory1/directory2/","");
  "c:/directory1/directory2"        --> Map.Entry("c:/directory1/directory2/",""); // directory2 is a dir!
  "c:/directory1/file2"             --> Map.Entry("c:/directory1/","file2");       // file2 is a file!
  "c:/"                             --> Map.Entry("c:/","");
    
 

Assuming, that '/' is the current file separator character.

If your string is retrieved from an URL instance, use cutDirectoryInformation(URL path) instead, because URL's do not depend on the operating systems file separator!

Parameters:

path - the absolute file path you want the mere file name of.

Returns:

the Map.Entry consisting of path information and file name.

cutExtension

public static Map.Entry cutExtension(String filename)

Cuts a String into the part before the last dot and after the last dot. If only one dot is contained on the first position, it will completely be used as prefix part.

 Map.Entry entry = FileUtil.getPotentialExtension("A.Very.Strange.Name.txt");
 String prefix = (String) entry.getKey(); // prefix is "A.Very.Strange.Name".
 String suffix = (String) entry.getValue(); // suffix is "txt";
 
 entry = FileUtil.getPotentialExtension(".profile");
 String prefix = (String) entry.getKey(); // prefix is ".profile".
 String suffix = (String) entry.getValue(); // suffix is "";
 
 entry = FileUtil.getPotentialExtension("bash");
 String prefix = (String) entry.getKey(); // prefix is "bash".
 String suffix = (String) entry.getValue(); // suffix is "";
 
 

Parameters:

filename - A String that is interpreted to be a file name: The last dot ('.') is interpreted to be the extension delimiter.

Returns:

A java.util.Map.Entry instance containing a String for the filename at the key side and a String for the extension at the value side.

getDefaultFileName

public static String getDefaultFileName(String name)

Finds a filename based on the given name. If a file with the given name does not exist, name will be returned.

Else:

  "myFile.out"     --> "myFile_0.out"
  "myFile_0.out"   --> "myFile_1.out"
  "myFile_1.out"   --> "myFile_2.out"
  ....
 

The potential extension is preserved, but a number is appended to the prefix name.

Parameters:

name - A desired file name.

Returns:

A String that sticks to the naming convention of the given String but is unique in the directory scope of argument name.

getInstance

public static FileUtil getInstance()

Returns the singleton instance of this class.

Returns:

the singleton instance of this class.

isAllASCII

public static boolean isAllASCII(File f)
                          throws IOException

Tests wether the given file only contains ASCII characters if interpreted by reading bytes (16 bit).

This does not mean that the file is really an ASCII text file. It just might be viewed with an editor showing only valid ASCII characters.

Parameters:

f - the file to test.

Returns:

true if all bytes in the file are in the ASCII range.

Throws:

IOException - on a bad day.

isAllASCII

public static boolean isAllASCII(InputStream in)
                          throws IOException

Tests wether the given input stream only contains ASCII characters if interpreted by reading bytes (16 bit).

This does not mean that the underlying content is really an ASCII text file. It just might be viewed with an editor showing only valid ASCII characters.

Parameters:

in - the stream to test.

Returns:

true if all bytes in the given input stream are in the ASCII range.

Throws:

IOException - on a bad day.

isEqual

public static boolean isEqual(File document,
                              Charset a,
                              Charset b)
                       throws IOException

Tests, wether the content of the given file is identical at character level, when it is opened with both different Charsets.

This is most often the case, if the given file only contains ASCII codes but may also occur, when both codepages cover common ranges and the document only contains values m_out of those ranges (like the EUC-CN charset contains all mappings from BIG5).

Parameters:

document - the file to test.

a - the first character set to interpret the document in.

b - the 2nd character set to interpret the document in.

Returns:

true if both files have all equal contents if they are interpreted as character data in both given encodings (they may differ at binary level if both charsets are different).

Throws:

IOException - if sth. goes wrong.

readCache

public static InputStream readCache(File f)
                             throws IOException

Invokes readRAM(File), but decorates the result with a ByteArrayInputStream.

This means: The complete content of the given File has been loaded before using the returned InputStream. There are no IO-delays afterwards but OutOfMemoryErrors may occur.

Parameters:

f - the file to cache.

Returns:

an input stream backed by the file read into memory.

Throws:

IOException - if sth. goes wrong.

readRAM

public static byte[] readRAM(File f)
                      throws IOException

Reads the content of the given File into an array.

This method currently does not check for maximum length and might cause a java.lang.OutOfMemoryError. It is only intended for performance-measurements of data-based algorithms that want to exclude I/O-usage.

Parameters:

f - the file to read.

Returns:

the contents of the given file.

Throws:

IOException - if sth. goes wrong.

removeDuplicateLineBreaks

public static void removeDuplicateLineBreaks(File f)

Removes the duplicate line breaks in the given file.

Be careful with big files: In order to avoid having to write a tmpfile (cannot read and directly write to the same file) a StringBuffer is used for manipulation. Big files will cost all RAM and terminate VM hard.

Parameters:

f - the file to remove duplicate line breaks in.

formatFilesize

public String formatFilesize(long filesize,
                             Locale locale)

Returns the formatted filesize to Bytes, KB, MB or GB depending on the given value.

Parameters:

filesize - in bytes

locale - the locale to translate the result to (e.g. in France they us

Returns:

the formatted filesize to Bytes, KB, MB or GB depending on the given value.