java.lang.Object
org.apache.commons.compress.archivers.zip.ZipUtil

public abstract class ZipUtil extends Object
Utility class for handling DOS and Java time conversions.
  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    private static final long
    DOS time constant for representing timestamps before 1980.
    private static final long
    Java time representation of the smallest date/time ZIP can handle
    private static final long
    Approximately 128 years, in milliseconds (ignoring leap years, etc.).
  • Constructor Summary

    Constructors
    Constructor
    Description
     
  • Method Summary

    Modifier and Type
    Method
    Description
    static long
    adjustToLong(int i)
    Assumes a negative integer really is a positive integer that has wrapped around and re-creates the original value.
    (package private) static long
    Converts a BigInteger into a long, and blows up (NumberFormatException) if the BigInteger is too big.
    (package private) static boolean
    Tests if this library is able to read or write the given entry.
    (package private) static void
    Checks whether the entry requires features not (yet) supported by the library and throws an exception if it does.
    (package private) static byte[]
    copy(byte[] from)
    Creates a copy of the given array - or return null if the argument is null.
    (package private) static void
    copy(byte[] from, byte[] to, int offset)
     
    private static Date
    dosToJavaDate(long dosTime)
     
    static long
    dosToJavaTime(long dosTime)
    Converts DOS time to Java time (number of milliseconds since epoch).
    static Date
    fromDosTime(ZipLong zipDosTime)
    Converts a DOS date/time field to a Date object.
    private static String
    If the stored CRC matches the one of the given name, return the Unicode name of the given field.
    static boolean
    isDosTime(long time)
    Tests whether a given time (in milliseconds since Epoch) can be safely represented as DOS time
    private static LocalDateTime
     
    private static long
    javaToDosTime(long t)
     
    (package private) static BigInteger
    longToBig(long l)
    Converts a long into a BigInteger.
    static byte[]
    reverse(byte[] array)
    Reverses a byte[] array.
    (package private) static void
    setNameAndCommentFromExtraFields(ZipArchiveEntry ze, byte[] originalNameBytes, byte[] commentBytes)
    If the entry has Unicode*ExtraFields and the CRCs of the names/comments match those of the extra fields, transfer the known Unicode values from the extra field.
    static int
    Converts a signed byte into an unsigned integer representation (e.g., -1 becomes 255).
    private static boolean
    Tests if this library supports the encryption used by the given entry.
    private static boolean
    Tests if this library supports the compression method used by the given entry.
    static byte[]
    toDosTime(long t)
    Converts a Date object to a DOS date/time field.
    static void
    toDosTime(long t, byte[] buf, int offset)
    Converts a Date object to a DOS date/time field.
    static ZipLong
    Converts a Date object to a DOS date/time field.
    static byte
    Converts an unsigned integer to a signed byte (e.g., 255 becomes -1).

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
  • Field Details

    • DOSTIME_BEFORE_1980

      private static final long DOSTIME_BEFORE_1980
      DOS time constant for representing timestamps before 1980. Smallest date/time ZIP can handle.

      MS-DOS records file dates and times as packed 16-bit values. An MS-DOS date has the following format.

      Bits Contents

      • 0-4: Day of the month (1-31).
      • 5-8: Month (1 = January, 2 = February, and so on).
      • 9-15: Year offset from 1980 (add 1980 to get the actual year).
      An MS-DOS time has the following format.

      Bits Contents

      • 0-4: Second divided by 2.
      • 5-10: Minute (0-59).
      • 11-15: Hour (0-23 on a 24-hour clock).
      This constant expresses the minimum DOS date of January 1st 1980 at 00:00:00 or, bit-by-bit:
      • Year: 0000000
      • Month: 0001
      • Day: 00001
      • Hour: 00000
      • Minute: 000000
      • Seconds: 00000

      This was copied from ZipEntry.

      Since:
      1.23
      See Also:
    • DOSTIME_BEFORE_1980_AS_JAVA_TIME

      private static final long DOSTIME_BEFORE_1980_AS_JAVA_TIME
      Java time representation of the smallest date/time ZIP can handle
    • UPPER_DOSTIME_BOUND

      private static final long UPPER_DOSTIME_BOUND
      Approximately 128 years, in milliseconds (ignoring leap years, etc.).

      This establish an approximate high-bound value for DOS times in milliseconds since epoch, used to enable an efficient but sufficient bounds check to avoid generating extended last modified time entries.

      Calculating the exact number is locale dependent, would require loading TimeZone data eagerly, and would make little practical sense. Since DOS times theoretically go to 2107 - with compatibility not guaranteed after 2099 - setting this to a time that is before but near 2099 should be sufficient.

      This was copied from ZipEntry.

      Since:
      1.23
      See Also:
  • Constructor Details

    • ZipUtil

      public ZipUtil()
  • Method Details

    • adjustToLong

      public static long adjustToLong(int i)
      Assumes a negative integer really is a positive integer that has wrapped around and re-creates the original value.
      Parameters:
      i - the value to treat as unsigned int.
      Returns:
      the unsigned int as a long.
    • bigToLong

      static long bigToLong(BigInteger big)
      Converts a BigInteger into a long, and blows up (NumberFormatException) if the BigInteger is too big.
      Parameters:
      big - BigInteger to convert.
      Returns:
      long representation of the BigInteger.
    • canHandleEntryData

      static boolean canHandleEntryData(ZipArchiveEntry entry)
      Tests if this library is able to read or write the given entry.
    • checkRequestedFeatures

      static void checkRequestedFeatures(ZipArchiveEntry ze) throws UnsupportedZipFeatureException
      Checks whether the entry requires features not (yet) supported by the library and throws an exception if it does.
      Throws:
      UnsupportedZipFeatureException
    • copy

      static byte[] copy(byte[] from)
      Creates a copy of the given array - or return null if the argument is null.
    • copy

      static void copy(byte[] from, byte[] to, int offset)
    • dosToJavaDate

      private static Date dosToJavaDate(long dosTime)
    • dosToJavaTime

      public static long dosToJavaTime(long dosTime)
      Converts DOS time to Java time (number of milliseconds since epoch).
      Parameters:
      dosTime - time to convert
      Returns:
      converted time
    • fromDosTime

      public static Date fromDosTime(ZipLong zipDosTime)
      Converts a DOS date/time field to a Date object.
      Parameters:
      zipDosTime - contains the stored DOS time.
      Returns:
      a Date instance corresponding to the given time.
    • getUnicodeStringIfOriginalMatches

      private static String getUnicodeStringIfOriginalMatches(AbstractUnicodeExtraField f, byte[] orig)
      If the stored CRC matches the one of the given name, return the Unicode name of the given field.

      If the field is null or the CRCs don't match, return null instead.

    • isDosTime

      public static boolean isDosTime(long time)
      Tests whether a given time (in milliseconds since Epoch) can be safely represented as DOS time
      Parameters:
      time - time in milliseconds since epoch
      Returns:
      true if the time can be safely represented as DOS time, false otherwise
      Since:
      1.23
    • javaEpochToLocalDateTime

      private static LocalDateTime javaEpochToLocalDateTime(long time)
    • javaToDosTime

      private static long javaToDosTime(long t)
    • longToBig

      static BigInteger longToBig(long l)

      Converts a long into a BigInteger. Negative numbers between -1 and -2^31 are treated as unsigned 32 bit (e.g., positive) integers. Negative numbers below -2^31 cause an IllegalArgumentException to be thrown.

      Parameters:
      l - long to convert to BigInteger.
      Returns:
      BigInteger representation of the provided long.
    • reverse

      public static byte[] reverse(byte[] array)
      Reverses a byte[] array. Reverses in-place (thus provided array is mutated), but also returns same for convenience.
      Parameters:
      array - to reverse (mutated in-place, but also returned for convenience).
      Returns:
      the reversed array (mutated in-place, but also returned for convenience).
      Since:
      1.5
    • setNameAndCommentFromExtraFields

      static void setNameAndCommentFromExtraFields(ZipArchiveEntry ze, byte[] originalNameBytes, byte[] commentBytes)
      If the entry has Unicode*ExtraFields and the CRCs of the names/comments match those of the extra fields, transfer the known Unicode values from the extra field.
    • signedByteToUnsignedInt

      public static int signedByteToUnsignedInt(byte b)
      Converts a signed byte into an unsigned integer representation (e.g., -1 becomes 255).
      Parameters:
      b - byte to convert to int
      Returns:
      int representation of the provided byte
      Since:
      1.5
    • supportsEncryptionOf

      private static boolean supportsEncryptionOf(ZipArchiveEntry entry)
      Tests if this library supports the encryption used by the given entry.
      Returns:
      true if the entry isn't encrypted at all
    • supportsMethodOf

      private static boolean supportsMethodOf(ZipArchiveEntry entry)
      Tests if this library supports the compression method used by the given entry.
      Returns:
      true if the compression method is supported
    • toDosTime

      public static ZipLong toDosTime(Date time)
      Converts a Date object to a DOS date/time field.
      Parameters:
      time - the Date to convert
      Returns:
      the date as a ZipLong
    • toDosTime

      public static byte[] toDosTime(long t)
      Converts a Date object to a DOS date/time field.

      Stolen from InfoZip's fileio.c

      Parameters:
      t - number of milliseconds since the epoch
      Returns:
      the date as a byte array
    • toDosTime

      public static void toDosTime(long t, byte[] buf, int offset)
      Converts a Date object to a DOS date/time field.

      Stolen from InfoZip's fileio.c

      Parameters:
      t - number of milliseconds since the epoch
      buf - the output buffer
      offset - The offset within the output buffer of the first byte to be written. must be non-negative and no larger than buf.length-4
    • unsignedIntToSignedByte

      public static byte unsignedIntToSignedByte(int i)
      Converts an unsigned integer to a signed byte (e.g., 255 becomes -1).
      Parameters:
      i - integer to convert to byte
      Returns:
      byte representation of the provided int
      Throws:
      IllegalArgumentException - if the provided integer is not inside the range [0,255].
      Since:
      1.5