Package org.apache.commons.compress.archivers.zip

Class ResourceAlignmentExtraField

java.lang.Object

org.apache.commons.compress.archivers.zip.ResourceAlignmentExtraField

All Implemented Interfaces:

ZipExtraField

public class ResourceAlignmentExtraField
extends Object
implements ZipExtraField

An extra field who's sole purpose is to align and pad the local file header so that the entry's data starts at a certain position.

The padding content of the padding is ignored and not retained when reading a padding field.

This enables Commons Compress to create "aligned" archives similar to Android's zipalign command line tool.

Since:

1.14

See Also:

• "https://developer.android.com/studio/command-line/zipalign.html"
• ZipArchiveEntry.setAlignment(int)

Field Summary

Fields

Modifier and Type	Field	Description
static final int	BASE_SIZE
static final ZipShort	ID	Extra field id used for storing alignment and padding.

Fields inherited from interface org.apache.commons.compress.archivers.zip.ZipExtraField

EXTRAFIELD_HEADER_SIZE

Constructor Summary

Constructors

Constructor	Description
ResourceAlignmentExtraField()
ResourceAlignmentExtraField(int alignment)
ResourceAlignmentExtraField(int alignment, boolean allowMethodChange)
ResourceAlignmentExtraField(int alignment, boolean allowMethodChange, int padding)

Method Summary

Modifier and Type	Method	Description
boolean	allowMethodChange()	Indicates whether method change is allowed when re-compressing the ZIP file.
short	getAlignment()	Gets requested alignment.
byte[]	getCentralDirectoryData()	The actual data to put into central directory - without Header-ID or length specifier.
ZipShort	getCentralDirectoryLength()	Length of the extra field in the central directory - without Header-ID or length specifier.
ZipShort	getHeaderId()	The Header-ID.
byte[]	getLocalFileDataData()	The actual data to put into local file data - without Header-ID or length specifier.
ZipShort	getLocalFileDataLength()	Length of the extra field in the local file data - without Header-ID or length specifier.
void	parseFromCentralDirectoryData(byte[] buffer, int offset, int length)	Populate data from this array as if it was in central directory data.
void	parseFromLocalFileData(byte[] buffer, int offset, int length)	Populate data from this array as if it was in local file data.

Methods inherited from class java.lang.Object

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

Field Details

ID

public static final ZipShort ID

Extra field id used for storing alignment and padding.

BASE_SIZE

public static final int BASE_SIZE

See Also:

• Constant Field Values

Constructor Details

ResourceAlignmentExtraField

public ResourceAlignmentExtraField()

ResourceAlignmentExtraField

public ResourceAlignmentExtraField(int alignment)

ResourceAlignmentExtraField

public ResourceAlignmentExtraField(int alignment,
 boolean allowMethodChange)

ResourceAlignmentExtraField

public ResourceAlignmentExtraField(int alignment,
 boolean allowMethodChange,
 int padding)

Method Details

allowMethodChange

public boolean allowMethodChange()

Indicates whether method change is allowed when re-compressing the ZIP file.

Returns:

true if method change is allowed, false otherwise.

getAlignment

public short getAlignment()

Gets requested alignment.

Returns:

requested alignment.

getCentralDirectoryData

public byte[] getCentralDirectoryData()

Description copied from interface: ZipExtraField

The actual data to put into central directory - without Header-ID or length specifier.

Specified by:

getCentralDirectoryData in interface ZipExtraField

Returns:

the data

getCentralDirectoryLength

public ZipShort getCentralDirectoryLength()

Description copied from interface: ZipExtraField

Length of the extra field in the central directory - without Header-ID or length specifier.

Specified by:

getCentralDirectoryLength in interface ZipExtraField

Returns:

the length of the field in the central directory

getHeaderId

public ZipShort getHeaderId()

Description copied from interface: ZipExtraField

The Header-ID.

Specified by:

getHeaderId in interface ZipExtraField

Returns:

The HeaderId value

getLocalFileDataData

public byte[] getLocalFileDataData()

Description copied from interface: ZipExtraField

The actual data to put into local file data - without Header-ID or length specifier.

Specified by:

getLocalFileDataData in interface ZipExtraField

Returns:

the data

getLocalFileDataLength

public ZipShort getLocalFileDataLength()

Description copied from interface: ZipExtraField

Length of the extra field in the local file data - without Header-ID or length specifier.

Specified by:

getLocalFileDataLength in interface ZipExtraField

Returns:

the length of the field in the local file data

parseFromCentralDirectoryData

public void parseFromCentralDirectoryData(byte[] buffer,
 int offset,
 int length)
                                   throws ZipException

Description copied from interface: ZipExtraField

Populate data from this array as if it was in central directory data.

Specified by:

parseFromCentralDirectoryData in interface ZipExtraField

Parameters:

buffer - the buffer to read data from

offset - offset into buffer to read data

length - the length of data

Throws:

ZipException - on error

parseFromLocalFileData

public void parseFromLocalFileData(byte[] buffer,
 int offset,
 int length)
                            throws ZipException

Description copied from interface: ZipExtraField

Populate data from this array as if it was in local file data.

Specified by:

parseFromLocalFileData in interface ZipExtraField

Parameters:

buffer - the buffer to read data from

offset - offset into buffer to read data

length - the length of data

Throws:

ZipException - on error