org.apache.tools.zip

Class GeneralPurposeBit

java.lang.Object

org.apache.tools.zip.GeneralPurposeBit

All Implemented Interfaces:

Cloneable

public final class GeneralPurposeBit
extends Object
implements Cloneable

Parser/encoder for the "general purpose bit" field in ZIP's local file and central directory headers.

Since:

Ant 1.9.0

Field Summary

Fields

Modifier and Type	Field and Description
static int	UFT8_NAMES_FLAG Indicates that filenames are written in utf-8.

Constructor Summary

Constructors

Constructor and Description
GeneralPurposeBit()

Method Summary

Modifier and Type	Method and Description
Object	clone() Creates and returns a copy of this object.
byte[]	encode() Encodes the set bits in a form suitable for ZIP archives.
void	encode(byte[] buf, int offset) Encodes the set bits in a form suitable for ZIP archives.
boolean	equals(Object o) Indicates whether some other object is "equal to" this one.
int	hashCode() Returns a hash code value for the object.
static GeneralPurposeBit	parse(byte[] data, int offset) Parses the supported flags from the given archive data.
void	useDataDescriptor(boolean b) whether the current entry will use the data descriptor to store CRC and size information
void	useEncryption(boolean b) whether the current entry will be encrypted
boolean	usesDataDescriptor() whether the current entry uses the data descriptor to store CRC and size information
boolean	usesEncryption() whether the current entry is encrypted
boolean	usesStrongEncryption() whether the current entry is encrypted using strong encryption
void	useStrongEncryption(boolean b) whether the current entry will be encrypted using strong encryption
boolean	usesUTF8ForNames() whether the current entry uses UTF8 for file name and comment.
void	useUTF8ForNames(boolean b) whether the current entry will use UTF8 for file name and comment.

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, toString, wait, wait, wait

Field Detail

UFT8_NAMES_FLAG

public static final int UFT8_NAMES_FLAG

Indicates that filenames are written in utf-8.

The only reason this is public is that ZipOutputStream.EFS_FLAG was public in several versions of Apache Ant and we needed a substitute for it.

See Also:

Constant Field Values

Constructor Detail

GeneralPurposeBit

public GeneralPurposeBit()

Method Detail

clone

public Object clone()

Description copied from class: Object

Creates and returns a copy of this object. The precise meaning of "copy" may depend on the class of the object. The general intent is that, for any object x, the expression:

 x.clone() != x
 

will be true, and that the expression:

 x.clone().getClass() == x.getClass()
 

will be true, but these are not absolute requirements. While it is typically the case that:

 x.clone().equals(x)
 

will be true, this is not an absolute requirement.

By convention, the returned object should be obtained by calling super.clone. If a class and all of its superclasses (except Object) obey this convention, it will be the case that x.clone().getClass() == x.getClass().

By convention, the object returned by this method should be independent of this object (which is being cloned). To achieve this independence, it may be necessary to modify one or more fields of the object returned by super.clone before returning it. Typically, this means copying any mutable objects that comprise the internal "deep structure" of the object being cloned and replacing the references to these objects with references to the copies. If a class contains only primitive fields or references to immutable objects, then it is usually the case that no fields in the object returned by super.clone need to be modified.

The method clone for class Object performs a specific cloning operation. First, if the class of this object does not implement the interface Cloneable, then a CloneNotSupportedException is thrown. Note that all arrays are considered to implement the interface Cloneable and that the return type of the clone method of an array type T[] is T[] where T is any reference or primitive type. Otherwise, this method creates a new instance of the class of this object and initializes all its fields with exactly the contents of the corresponding fields of this object, as if by assignment; the contents of the fields are not themselves cloned. Thus, this method performs a "shallow copy" of this object, not a "deep copy" operation.

The class Object does not itself implement the interface Cloneable, so calling the clone method on an object whose class is Object will result in throwing an exception at run time.

Overrides:

clone in class Object

Returns:

a clone of this instance.

See Also:

Cloneable

encode

public byte[] encode()

Encodes the set bits in a form suitable for ZIP archives.

encode

public void encode(byte[] buf,
                   int offset)

Encodes the set bits in a form suitable for ZIP archives.

Parameters:

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-2

equals

public boolean equals(Object o)

Description copied from class: Object

Indicates whether some other object is "equal to" this one.

The equals method implements an equivalence relation on non-null object references:

• It is reflexive: for any non-null reference value x, x.equals(x) should return true.
• It is symmetric: for any non-null reference values x and y, x.equals(y) should return true if and only if y.equals(x) returns true.
• It is transitive: for any non-null reference values x, y, and z, if x.equals(y) returns true and y.equals(z) returns true, then x.equals(z) should return true.
• It is consistent: for any non-null reference values x and y, multiple invocations of x.equals(y) consistently return true or consistently return false, provided no information used in equals comparisons on the objects is modified.
• For any non-null reference value x, x.equals(null) should return false.

The equals method for class Object implements the most discriminating possible equivalence relation on objects; that is, for any non-null reference values x and y, this method returns true if and only if x and y refer to the same object (x == y has the value true).

Note that it is generally necessary to override the hashCode method whenever this method is overridden, so as to maintain the general contract for the hashCode method, which states that equal objects must have equal hash codes.

Overrides:

equals in class Object

Parameters:

o - the reference object with which to compare.

Returns:

true if this object is the same as the obj argument; false otherwise.

See Also:

Object.hashCode(), HashMap

hashCode

public int hashCode()

Description copied from class: Object

Returns a hash code value for the object. This method is supported for the benefit of hash tables such as those provided by HashMap.

The general contract of hashCode is:

• Whenever it is invoked on the same object more than once during an execution of a Java application, the hashCode method must consistently return the same integer, provided no information used in equals comparisons on the object is modified. This integer need not remain consistent from one execution of an application to another execution of the same application.
• If two objects are equal according to the equals(Object) method, then calling the hashCode method on each of the two objects must produce the same integer result.
• It is not required that if two objects are unequal according to the Object.equals(java.lang.Object) method, then calling the hashCode method on each of the two objects must produce distinct integer results. However, the programmer should be aware that producing distinct integer results for unequal objects may improve the performance of hash tables.

As much as is reasonably practical, the hashCode method defined by class Object does return distinct integers for distinct objects. (This is typically implemented by converting the internal address of the object into an integer, but this implementation technique is not required by the Java^TM programming language.)

Overrides:

hashCode in class Object

Returns:

a hash code value for this object.

See Also:

Object.equals(java.lang.Object), System.identityHashCode(java.lang.Object)

parse

public static GeneralPurposeBit parse(byte[] data,
                                      int offset)

Parses the supported flags from the given archive data.

Parameters:

data - local file header or a central directory entry.

offset - offset at which the general purpose bit starts

useDataDescriptor

public void useDataDescriptor(boolean b)

whether the current entry will use the data descriptor to store CRC and size information

useEncryption

public void useEncryption(boolean b)

whether the current entry will be encrypted

usesDataDescriptor

public boolean usesDataDescriptor()

whether the current entry uses the data descriptor to store CRC and size information

usesEncryption

public boolean usesEncryption()

whether the current entry is encrypted

usesStrongEncryption

public boolean usesStrongEncryption()

whether the current entry is encrypted using strong encryption

useStrongEncryption

public void useStrongEncryption(boolean b)

whether the current entry will be encrypted using strong encryption

usesUTF8ForNames

public boolean usesUTF8ForNames()

whether the current entry uses UTF8 for file name and comment.

useUTF8ForNames

public void useUTF8ForNames(boolean b)

whether the current entry will use UTF8 for file name and comment.