Package org.apache.commons.io

Enum FileSystem

java.lang.Object
java.lang.Enum<FileSystem>
org.apache.commons.io.FileSystem
All Implemented Interfaces:
Serializable, Comparable<FileSystem>
public enum FileSystem extends Enum<FileSystem>
Enumerates file system details for operating systems, currently supporting the single use case of converting a file name String to a legal file name with toLegalFileName(String, char).

The starting point of any operation is getCurrent() which gets you the enum for the file system that matches the OS hosting the running JVM.

Since:
2.7

  • Enum Constant Details

  • Field Details

    • IS_OS_LINUX

      private static final boolean IS_OS_LINUX
      Is true if this is Linux.

      The field will return false if OS_NAME is null.

    • IS_OS_MAC

      private static final boolean IS_OS_MAC
      Is true if this is Mac.

      The field will return false if OS_NAME is null.

    • OS_NAME_WINDOWS_PREFIX

      private static final String OS_NAME_WINDOWS_PREFIX
      The prefix String for all Windows OS.
      See Also:

    • IS_OS_WINDOWS

      private static final boolean IS_OS_WINDOWS
      Is true if this is Windows.

      The field will return false if OS_NAME is null.

    • CURRENT

      private static final FileSystem CURRENT
      The current FileSystem.

    • blockSize

      private final int blockSize

    • casePreserving

      private final boolean casePreserving

    • caseSensitive

      private final boolean caseSensitive

    • illegalFileNameChars

      private final int[] illegalFileNameChars

    • maxFileNameLength

      private final int maxFileNameLength

    • maxPathLength

      private final int maxPathLength

    • reservedFileNames

      private final String[] reservedFileNames

    • reservedFileNamesExtensions

      private final boolean reservedFileNamesExtensions

    • supportsDriveLetter

      private final boolean supportsDriveLetter

    • nameSeparator

      private final char nameSeparator

    • nameSeparatorOther

      private final char nameSeparatorOther

    • nameLengthStrategy

      private final FileSystem.NameLengthStrategy nameLengthStrategy

  • Constructor Details

    • FileSystem

      private FileSystem(int blockSize, boolean caseSensitive, boolean casePreserving, int maxFileLength, int maxPathLength, int[] illegalFileNameChars, String[] reservedFileNames, boolean reservedFileNamesExtensions, boolean supportsDriveLetter, char nameSeparator, FileSystem.NameLengthStrategy nameLengthStrategy)
      Constructs a new instance.
      Parameters:
      blockSize - file allocation block size in bytes.
      caseSensitive - Whether this file system is case-sensitive.
      casePreserving - Whether this file system is case-preserving.
      maxFileLength - The maximum length for file names. The file name does not include folders.
      maxPathLength - The maximum length of the path to a file. This can include folders.
      illegalFileNameChars - Illegal characters for this file system.
      reservedFileNames - The reserved file names.
      reservedFileNamesExtensions - The reserved file name extensions.
      supportsDriveLetter - Whether this file system support driver letters.
      nameSeparator - The name separator, '\\' on Windows, '/' on Linux.
      nameLengthStrategy - The strategy for measuring and truncating file and path names.

  • Method Details

    • values

      public static FileSystem[] values()
      Returns an array containing the constants of this enum type, in the order they are declared.
      Returns:
      an array containing the constants of this enum type, in the order they are declared

    • valueOf

      public static FileSystem valueOf(String name)
      Returns the enum constant of this type with the specified name. The string must match exactly an identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)
      Parameters:
      name - the name of the enum constant to be returned.
      Returns:
      the enum constant with the specified name
      Throws:
      IllegalArgumentException - if this enum type has no constant with the specified name
      NullPointerException - if the argument is null

    • current

      private static FileSystem current()
      Gets the current file system.
      Returns:
      the current file system.

    • getCurrent

      public static FileSystem getCurrent()
      Gets the current file system.
      Returns:
      the current file system.

    • getOsMatchesName

      private static boolean getOsMatchesName(String osNamePrefix)
      Decides if the operating system matches.
      Parameters:
      osNamePrefix - the prefix for the operating system name.
      Returns:
      true if matches, or false if not or can't determine.

    • getSystemProperty

      private static String getSystemProperty(String property)
      Gets a System property, defaulting to null if the property cannot be read.

      If a SecurityException is caught, the return value is null and a message is written to System.err.

      Parameters:
      property - the system property name.
      Returns:
      the system property value or null if a security problem occurs.

    • indexOfFirstDot

      private static int indexOfFirstDot(CharSequence cs)

    • isOsNameMatch

      private static boolean isOsNameMatch(String osName, String osNamePrefix)
      Decides if the operating system matches.

      This method is package private instead of private to support unit test invocation.

      Parameters:
      osName - the actual OS name.
      osNamePrefix - the prefix for the expected OS name.
      Returns:
      true if matches, or false if not or can't determine.

    • replace

      private static String replace(String path, char oldChar, char newChar)
      Null-safe replace.
      Parameters:
      path - the path to be changed, null ignored.
      oldChar - the old character.
      newChar - the new character.
      Returns:
      the new path.

    • safeTruncate

      private static CharSequence safeTruncate(CharSequence value, int limit)
      Truncates a string respecting grapheme cluster boundaries.
      Parameters:
      value - The value to truncate.
      limit - The maximum length.
      Returns:
      The truncated value.
      Throws:
      IllegalArgumentException - If the first grapheme cluster is longer than the limit.

    • splitExtension

      static CharSequence[] splitExtension(CharSequence value)

    • trimExtension

      static CharSequence trimExtension(CharSequence cs)

    • getBlockSize

      public int getBlockSize()
      Gets the file allocation block size in bytes.
      Returns:
      the file allocation block size in bytes.
      Since:
      2.12.0

    • getIllegalFileNameChars

      public char[] getIllegalFileNameChars()
      Gets a cloned copy of the illegal characters for this file system.
      Returns:
      the illegal characters for this file system.

    • getIllegalFileNameCodePoints

      public int[] getIllegalFileNameCodePoints()
      Gets a cloned copy of the illegal code points for this file system.
      Returns:
      the illegal code points for this file system.
      Since:
      2.12.0

    • getMaxFileNameLength

      public int getMaxFileNameLength()
      Gets the maximum length for file names (excluding any folder path).

      This limit applies only to the file name itself, excluding any parent directories.

      The value is expressed in Java char units (UTF-16 code units).

      Note: Because many file systems enforce limits in bytes using a specific encoding rather than in UTF-16 code units, a name that fits this limit may still be rejected by the underlying file system.

      Use isLegalFileName(java.lang.CharSequence) to check whether a given name is valid for the current file system and charset.

      However, any file name longer than this limit is guaranteed to be invalid on the current file system.

      Returns:
      the maximum file name length in characters.

    • getMaxPathLength

      public int getMaxPathLength()
      Gets the maximum length for file paths (may include folders).

      This value is inclusive of all path components and separators. For a limit of each path component see getMaxFileNameLength().

      The value is expressed in Java char units (UTF-16 code units) and represents the longest path that can be safely passed to Java File and Path APIs.

      Note: many operating systems and file systems enforce path length limits in bytes using a specific encoding, rather than in UTF-16 code units. As a result, a path that fits within this limit may still be rejected by the underlying platform.

      Conversely, any path longer than this limit is guaranteed to fail with at least some operating system API calls.

      Returns:
      the maximum file path length in characters.

    • getNameLengthStrategy

      FileSystem.NameLengthStrategy getNameLengthStrategy()

    • getNameSeparator

      public char getNameSeparator()
      Gets the name separator, '\\' on Windows, '/' on Linux.
      Returns:
      '\\' on Windows, '/' on Linux.
      Since:
      2.12.0

    • getReservedFileNames

      public String[] getReservedFileNames()
      Gets a cloned copy of the reserved file names.
      Returns:
      the reserved file names.

    • isCasePreserving

      public boolean isCasePreserving()
      Tests whether this file system preserves case.
      Returns:
      Whether this file system preserves case.

    • isCaseSensitive

      public boolean isCaseSensitive()
      Tests whether this file system is case-sensitive.
      Returns:
      Whether this file system is case-sensitive.

    • isIllegalFileNameChar

      private boolean isIllegalFileNameChar(int c)
      Tests if the given character is illegal in a file name, false otherwise.
      Parameters:
      c - the character to test.
      Returns:
      true if the given character is illegal in a file name, false otherwise.

    • isLegalFileName

      public boolean isLegalFileName(CharSequence candidate)
      Tests if a candidate file name (without a path) is a legal file name.

      Takes a file name like "filename.ext" or "filename" and checks:

      • if the file name length is legal
      • if the file name is not a reserved file name
      • if the file name does not contain illegal characters
      Parameters:
      candidate - A candidate file name (without a path) like "filename.ext" or "filename".
      Returns:
      true if the candidate name is legal.

    • isLegalFileName

      public boolean isLegalFileName(CharSequence candidate, Charset charset)
      Tests if a candidate file name (without a path) is a legal file name.

      Takes a file name like "filename.ext" or "filename" and checks:

      • if the file name length is legal
      • if the file name is not a reserved file name
      • if the file name does not contain illegal characters
      Parameters:
      candidate - A candidate file name (without a path) like "filename.ext" or "filename".
      charset - The charset to use when the file name length is measured in bytes.
      Returns:
      true if the candidate name is legal.
      Since:
      2.21.0

    • isReservedFileName

      public boolean isReservedFileName(CharSequence candidate)
      Tests whether the given string is a reserved file name.
      Parameters:
      candidate - the string to test.
      Returns:
      true if the given string is a reserved file name.

    • normalizeSeparators

      public String normalizeSeparators(String path)
      Converts all separators to the Windows separator of backslash.
      Parameters:
      path - the path to be changed, null ignored.
      Returns:
      the updated path.
      Since:
      2.12.0

    • supportsDriveLetter

      public boolean supportsDriveLetter()
      Tests whether this file system support driver letters.

      Windows supports driver letters as do other operating systems. Whether these other OS's still support Java like OS/2, is a different matter.

      Returns:
      whether this file system support driver letters.
      Since:
      2.9.0
      See Also:

    • toLegalFileName

      public String toLegalFileName(CharSequence candidate, char replacement, Charset charset)
      Converts a candidate file name (without a path) to a legal file name.

      Takes a file name like "filename.ext" or "filename" and:

      • replaces illegal characters by the given replacement character
      • truncates the name to getMaxFileNameLength() if necessary
      Parameters:
      candidate - A candidate file name (without a path) like "filename.ext" or "filename".
      replacement - Illegal characters in the candidate name are replaced by this character.
      charset - The charset to use when the file name length is measured in bytes.
      Returns:
      a String without illegal characters.
      Since:
      2.21.0

    • toLegalFileName

      public String toLegalFileName(String candidate, char replacement)
      Converts a candidate file name (without a path) to a legal file name.

      Takes a file name like "filename.ext" or "filename" and:

      • replaces illegal characters by the given replacement character
      • truncates the name to getMaxFileNameLength() if necessary
      Parameters:
      candidate - A candidate file name (without a path) like "filename.ext" or "filename".
      replacement - Illegal characters in the candidate name are replaced by this character.
      Returns:
      a String without illegal characters.