OpenCard  
 
OCF, the OpenCard Framework is a standard Java framework for working with Smart Cards.  
 

opencard.opt.util
Class TLV

java.lang.Object
  |
  +--opencard.opt.util.TLV
public class TLV
extends java.lang.Object

This class represents a TLV (Tag Length Value) structure. There are methods for creating trees consisting of TLV objects from ASN.1 BER encoded byte sequences and for creating byte sequences from TLV object trees. All manipulations are done on the tree structure.

Version:
$Id: TLV.java,v 1.2 1999/11/03 12:37:19 damke Exp $
See Also:
Tag

Constructor Summary
TLV()
          Create an empty TLV.
TLV(byte[] binary)
          Create a TLV object from an ASN.1 BER encoded byte array.
TLV(Tag tag, byte[] value)
          Create a TLV object from the given Tag object and data. If the given Tag object has the constructed bit set, the result will be a TLV tree, otherwise it's just a primitive TLV that contains the data given in value field.
TLV(Tag tag, int number)
          Create a primitive TLV object from a given tag and positive integer.
TLV(Tag tag, TLV tlv)
          Create a constructed TLV object from the given Tag object and TLV object to be contained.
 
Method Summary
 TLV add(TLV tlv)
          Add the given TLV object to this TLV instance (only if constructed).
 TLV findTag(Tag tag, TLV cursor)
          Search for a given tag value and return the first TLV found.
static void fromBinary(byte[] binary, int[] offset, TLV tlv, TLV parent)
          Read a TLV object from a binary representation.
static int lenBytes(int length)
          Return the number of bytes required for coding the passed integer value as described in the ASN.1 Basic Encoding Rules.
 int length()
          Get the length of this TLV's value field in bytes.
static byte[] lengthToBinary(int length)
          BER-code the length of this TLV.
 void setValue(byte[] newValue)
          Set the value field of this TLV from the byte array.
 Tag tag()
          Get the tag of this TLV.
 byte[] toBinary()
          BER-code this TLV.
 byte[] toBinaryContent()
          BER-code this TLV's value field.
 java.lang.String toString()
          Convert a TLV to a string.
 java.lang.String toString(java.util.Hashtable ht, int level)
          Convert a TLV to a string.
 byte[] valueAsByteArray()
          Get the value field of this TLV as a byte array.
 int valueAsNumber()
          Get the value of this TLV as a positive integer number.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Constructor Detail

TLV

public TLV()
Create an empty TLV.

TLV

public TLV(byte[] binary)
Create a TLV object from an ASN.1 BER encoded byte array.

Parameters:
binary - A byte array containing the binary representation of a TLV structure, encoded conforming to the ASN.1 Basic Encoding Rules defined in ISO 8825.

TLV

public TLV(Tag tag,
           byte[] value)
Create a TLV object from the given Tag object and data.

If the given Tag object has the constructed bit set, the result will be a TLV tree, otherwise it's just a primitive TLV that contains the data given in value field.

Parameters:
tag - An instance of class Tag representing the tag field of the TLV to be created.
value - An array of bytes representing the Value field of the TLV to be created.

TLV

public TLV(Tag tag,
           int number)
Create a primitive TLV object from a given tag and positive integer.

Parameters:
tag - An instance of class Tag representing the tag field of the TLV to be created.
number - An integer representing the Value field of the TLV to be created.

TLV

public TLV(Tag tag,
           TLV tlv)
Create a constructed TLV object from the given Tag object and TLV object to be contained.
Parameters:
tag - An instance of class Tag representing the tag field of the TLV to be created.
tlv - An instance of class TLV representing the Value field of the TLV to be created.
Method Detail

add

public TLV add(TLV tlv)
Add the given TLV object to this TLV instance (only if constructed).

Parameters:
tlv - The TLV object to be concatenated to this TLV instance.

findTag

public TLV findTag(Tag tag,
                   TLV cursor)
Search for a given tag value and return the first TLV found.

Parameters:
tag - The Tag object representing the tag to be searched for, null for any tag.
cursor - A reference to a TLV object where the search should start; if null, the search is started with the child of this TLV instance.
Returns:
The first TLV object found, which has the given tag value; null if no match is found.

fromBinary

public static void fromBinary(byte[] binary,
                              int[] offset,
                              TLV tlv,
                              TLV parent)
Read a TLV object from a binary representation.

Parameters:
binary - A byte array containing the binary representation of a TLV structure, encoded conforming to the ASN.1 Basic Encoding Rules defined in ISO 8825.
offset - An integer value giving the offset, where the binary representation starts.
tlv - The TLV object to be read from the binary representation.
parent - The TLV object representing the parent of the object to be read.
Returns:
An integer value giving the offset of the end of the binary representation read into the TLV object.

lenBytes

public static int lenBytes(int length)
Return the number of bytes required for coding the passed integer value as described in the ASN.1 Basic Encoding Rules.

Parameters:
length - An integer value.
Returns:
An integer value giving the number of bytes.

length

public int length()
Get the length of this TLV's value field in bytes.

Returns:
An integer giving the length.

lengthToBinary

public static byte[] lengthToBinary(int length)
BER-code the length of this TLV.

Parameters:
binary - The byte array to which the BER-coded length field shall be added.
offset - The offset, where the BER-coded length field shall be added.

setValue

public void setValue(byte[] newValue)
Set the value field of this TLV from the byte array.

Parameters:
newValue - The byte array for the value field.

tag

public Tag tag()
Get the tag of this TLV.

Returns:
The Tag object of this TLV object.

toBinary

public byte[] toBinary()
BER-code this TLV.

Returns:
A byte array containing the BER-coded representation of this TLV instance.

toBinaryContent

public byte[] toBinaryContent()
BER-code this TLV's value field.

Returns:
A byte array containing the BER-coded binary representation of the value field of this TLV instance.

toString

public java.lang.String toString()
Convert a TLV to a string.

Returns:
A String object representing this TLV object.
Overrides:
toString in class java.lang.Object

toString

public java.lang.String toString(java.util.Hashtable ht,
                                 int level)
Convert a TLV to a string.

Parameters:
ht - A Hashtable object mapping Tag objects to objects.
level - An integer value giving the indention leve to be used.
Returns:
A String object representing this TLV object.

valueAsByteArray

public byte[] valueAsByteArray()
Get the value field of this TLV as a byte array.

Returns:
A byte array representing the value field of this TLV instance; null if the TLV is constructed.

valueAsNumber

public int valueAsNumber()
Get the value of this TLV as a positive integer number.

Returns:
An integer representing the value (unsigned int) of this TLV instance's value field.