com.android.tools.build.apkzlib.zip

Class ExtraField

java.lang.Object

com.android.tools.build.apkzlib.zip.ExtraField

public class ExtraField
extends java.lang.Object

Contains an extra field.

According to the zip specification, the extra field is composed of a sequence of fields. This class provides a way to access, parse and modify that information.

The zip specification calls fields to the fields inside the extra field. Because this terminology is confusing, we use segment to refer to a part of the extra field. Each segment is represented by an instance of ExtraField.Segment and contains a header ID and data.

Each instance of ExtraField is immutable. The extra field of a particular entry can be changed by creating a new instanceof ExtraField and pass it to StoredEntry.setLocalExtra(ExtraField).

Instances of ExtraField can be created directly from the list of segments in it or from the raw byte data. If created from the raw byte data, the data will only be parsed on demand. So, if neither getSegments() nor getSingleSegment(int) is invoked, the extra field will not be parsed. This guarantees low performance impact of the using the extra field unless its contents are needed.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	ExtraField.AlignmentSegment Segment with information on an alignment: this segment contains information on how an entry should be aligned and contains zero-filled data to force alignment.
static class	ExtraField.RawDataSegment Segment of raw data: this class represents a general segment containing an array of bytes as data.
static interface	ExtraField.Segment Field inside the extra field.

Constructor Summary

Constructors

Constructor and Description
ExtraField() Creates a new extra field with no segments.
ExtraField(byte[] rawData) Creates an extra field based on existing raw data.
ExtraField(com.google.common.collect.ImmutableList<ExtraField.Segment> segments) Creates a new extra field with the given segments.

Method Summary

Modifier and Type	Method and Description
com.google.common.collect.ImmutableList<ExtraField.Segment>	getSegments() Obtains all segments in the extra field.
ExtraField.Segment	getSingleSegment(int headerId) Obtains the only segment with the provided header ID.
int	size() Obtains the size of the extra field.
void	write(java.nio.ByteBuffer out) Writes the extra field to the given output buffer.

Methods inherited from class java.lang.Object

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

Constructor Detail

ExtraField

public ExtraField(byte[] rawData)

Creates an extra field based on existing raw data.

Parameters:

rawData - the raw data; will not be parsed unless needed

ExtraField

public ExtraField()

Creates a new extra field with no segments.

ExtraField

public ExtraField(com.google.common.collect.ImmutableList<ExtraField.Segment> segments)

Creates a new extra field with the given segments.

Parameters:

segments - the segments

Method Detail

getSegments

public com.google.common.collect.ImmutableList<ExtraField.Segment> getSegments()
                                                                        throws java.io.IOException

Obtains all segments in the extra field.

Returns:

all segments

Throws:

java.io.IOException - failed to parse the extra field

getSingleSegment

@Nullable
public ExtraField.Segment getSingleSegment(int headerId)
                                              throws java.io.IOException

Obtains the only segment with the provided header ID.

Parameters:

headerId - the header ID

Returns:

the segment found or null if no segment contains the provided header ID

Throws:

java.io.IOException - there is more than one header with the provided header ID

size

public int size()

Obtains the size of the extra field.

Returns:

the size

write

public void write(java.nio.ByteBuffer out)
           throws java.io.IOException

Writes the extra field to the given output buffer.

Parameters:

out - the output buffer to write the field; exactly size() bytes will be written

Throws:

java.io.IOException - failed to write the extra fields