org.apache.commons.compress.archivers.zip

Class Simple8BitZipEncoding

java.lang.Object

org.apache.commons.compress.archivers.zip.Simple8BitZipEncoding

All Implemented Interfaces:

ZipEncoding

class Simple8BitZipEncoding
extends java.lang.Object
implements ZipEncoding

This ZipEncoding implementation implements a simple 8bit character set, which mets the following restrictions:

• Characters 0x0000 to 0x007f are encoded as the corresponding byte values 0x00 to 0x7f.
• All byte codes from 0x80 to 0xff are mapped to a unique unicode character in the range 0x0080 to 0x7fff. (No support for UTF-16 surrogates)

These restrictions most notably apply to the most prominent omissions of java-1.4's Charset implementation, Cp437 and Cp850.

The methods of this class are reentrant.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
private static class	Simple8BitZipEncoding.Simple8BitChar A character entity, which is put to the reverse mapping table of a simple encoding.

Field Summary

Fields

Modifier and Type	Field and Description
private char[]	highChars The characters for byte values of 128 to 255 stored as an array of 128 chars.
private java.util.List<Simple8BitZipEncoding.Simple8BitChar>	reverseMapping A list of Simple8BitZipEncoding.Simple8BitChar objects sorted by the unicode field.

Constructor Summary

Constructors

Constructor and Description
Simple8BitZipEncoding(char[] highChars)

Method Summary

Modifier and Type	Method and Description
boolean	canEncode(java.lang.String name) Check, whether the given string may be losslessly encoded using this encoding.
boolean	canEncodeChar(char c)
java.lang.String	decode(byte[] data)
char	decodeByte(byte b) Return the character code for a given encoded byte.
java.nio.ByteBuffer	encode(java.lang.String name) Encode a filename or a comment to a byte array suitable for storing it to a serialized zip entry.
private Simple8BitZipEncoding.Simple8BitChar	encodeHighChar(char c)
boolean	pushEncodedChar(java.nio.ByteBuffer bb, char c) Pushes the encoded form of the given character to the given byte buffer.

Methods inherited from class java.lang.Object

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

Field Detail

highChars

private final char[] highChars

The characters for byte values of 128 to 255 stored as an array of 128 chars.

reverseMapping

private final java.util.List<Simple8BitZipEncoding.Simple8BitChar> reverseMapping

A list of Simple8BitZipEncoding.Simple8BitChar objects sorted by the unicode field. This list is used to binary search reverse mapping of unicode characters with a character code greater than 127.

Constructor Detail

Simple8BitZipEncoding

public Simple8BitZipEncoding(char[] highChars)

Parameters:

highChars - The characters for byte values of 128 to 255 stored as an array of 128 chars.

Method Detail

decodeByte

public char decodeByte(byte b)

Return the character code for a given encoded byte.

Parameters:

b - The byte to decode.

Returns:

The associated character value.

canEncodeChar

public boolean canEncodeChar(char c)

Parameters:

c - The character to encode.

Returns:

Whether the given unicode character is covered by this encoding.

pushEncodedChar

public boolean pushEncodedChar(java.nio.ByteBuffer bb,
                               char c)

Pushes the encoded form of the given character to the given byte buffer.

Parameters:

bb - The byte buffer to write to.

c - The character to encode.

Returns:

Whether the given unicode character is covered by this encoding. If false is returned, nothing is pushed to the byte buffer.

encodeHighChar

private Simple8BitZipEncoding.Simple8BitChar encodeHighChar(char c)

Parameters:

c - A unicode character in the range from 0x0080 to 0x7f00

Returns:

A Simple8BitChar, if this character is covered by this encoding. A null value is returned, if this character is not covered by this encoding.

canEncode

public boolean canEncode(java.lang.String name)

Description copied from interface: ZipEncoding

Check, whether the given string may be losslessly encoded using this encoding.

Specified by:

canEncode in interface ZipEncoding

Parameters:

name - A filename or ZIP comment.

Returns:

Whether the given name may be encoded with out any losses.

See Also:

ZipEncoding.canEncode(java.lang.String)

encode

public java.nio.ByteBuffer encode(java.lang.String name)

Description copied from interface: ZipEncoding

Encode a filename or a comment to a byte array suitable for storing it to a serialized zip entry.

Examples for CP 437 (in pseudo-notation, right hand side is C-style notation):

  encode("?_for_Dollar.txt") = "%U20AC_for_Dollar.txt"
  encode("Ölfässer.txt") = "\231lf\204sser.txt"
 

Specified by:

encode in interface ZipEncoding

Parameters:

name - A filename or ZIP comment.

Returns:

A byte buffer with a backing array containing the encoded name. Unmappable characters or malformed character sequences are mapped to a sequence of utf-16 words encoded in the format %Uxxxx. It is assumed, that the byte buffer is positioned at the beginning of the encoded result, the byte buffer has a backing array and the limit of the byte buffer points to the end of the encoded result.

See Also:

ZipEncoding.encode(java.lang.String)

decode

public java.lang.String decode(byte[] data)
                        throws java.io.IOException

Specified by:

decode in interface ZipEncoding

Parameters:

data - The byte values to decode.

Returns:

The decoded string.

Throws:

java.io.IOException - on error

See Also:

ZipEncoding.decode(byte[])