org.apache.commons.compress.archivers.sevenz

Class SevenZFile

java.lang.Object

org.apache.commons.compress.archivers.sevenz.SevenZFile

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable

public class SevenZFile
extends java.lang.Object
implements java.io.Closeable

Reads a 7z file, using RandomAccessFile under the covers.

The 7z file format is a flexible container that can contain many compression and encryption types, but at the moment only only Copy, LZMA, LZMA2, BZIP2, Deflate and AES-256 + SHA-256 are supported.

The format is very Windows/Intel specific, so it uses little-endian byte order, doesn't store user/group or permission bits, and represents times using NTFS timestamps (100 nanosecond units since 1 January 1601). Hence the official tools recommend against using it for backup purposes on *nix, and recommend .tar.7z or .tar.lzma or .tar.xz instead.

Both the header and file contents may be compressed and/or encrypted. With both encrypted, neither file names nor file contents can be read, but the use of encryption isn't plausibly deniable.

Since:

1.6

Constructor Summary

Constructors

Constructor and Description
SevenZFile(java.io.File filename) Reads a file as unecrypted 7z archive
SevenZFile(java.io.File filename, byte[] password) Reads a file as 7z archive

Method Summary

Modifier and Type	Method and Description
void	close() Closes the archive.
SevenZArchiveEntry	getNextEntry() Returns the next Archive Entry in this archive.
static boolean	matches(byte[] signature, int length) Checks if the signature matches what is expected for a 7z file.
int	read() Reads a byte of data.
int	read(byte[] b) Reads data into an array of bytes.
int	read(byte[] b, int off, int len) Reads data into an array of bytes.

Methods inherited from class java.lang.Object

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

Constructor Detail

SevenZFile

public SevenZFile(java.io.File filename,
                  byte[] password)
           throws java.io.IOException

Reads a file as 7z archive

Parameters:

filename - the file to read

password - optional password if the archive is encrypted - the byte array is supposed to be the UTF16-LE encoded representation of the password.

Throws:

java.io.IOException - if reading the archive fails

SevenZFile

public SevenZFile(java.io.File filename)
           throws java.io.IOException

Reads a file as unecrypted 7z archive

Parameters:

filename - the file to read

Throws:

java.io.IOException - if reading the archive fails

Method Detail

close

public void close()
           throws java.io.IOException

Closes the archive.

Specified by:

close in interface java.io.Closeable

Specified by:

close in interface java.lang.AutoCloseable

Throws:

java.io.IOException - if closing the file fails

getNextEntry

public SevenZArchiveEntry getNextEntry()
                                throws java.io.IOException

Returns the next Archive Entry in this archive.

Returns:

the next entry, or null if there are no more entries

Throws:

java.io.IOException - if the next entry could not be read

read

public int read()
         throws java.io.IOException

Reads a byte of data.

Returns:

the byte read, or -1 if end of input is reached

Throws:

java.io.IOException - if an I/O error has occurred

read

public int read(byte[] b)
         throws java.io.IOException

Reads data into an array of bytes.

Parameters:

b - the array to write data to

Returns:

the number of bytes read, or -1 if end of input is reached

Throws:

java.io.IOException - if an I/O error has occurred

read

public int read(byte[] b,
                int off,
                int len)
         throws java.io.IOException

Reads data into an array of bytes.

Parameters:

b - the array to write data to

off - offset into the buffer to start filling at

len - of bytes to read

Returns:

the number of bytes read, or -1 if end of input is reached

Throws:

java.io.IOException - if an I/O error has occurred

matches

public static boolean matches(byte[] signature,
                              int length)

Checks if the signature matches what is expected for a 7z file.

Parameters:

signature - the bytes to check

length - the number of bytes to check

Returns:

true, if this is the signature of a 7z archive.

Since:

1.8