Module java.smartcardio

Package javax.smartcardio

Class CardChannel

java.lang.Object

javax.smartcardio.CardChannel

public abstract class CardChannel
extends Object

A logical channel connection to a Smart Card. It is used to exchange APDUs with a Smart Card. A CardChannel object can be obtained by calling the method Card.getBasicChannel() or Card.openLogicalChannel().

Since:

1.6

See Also:

• Card
• CommandAPDU
• ResponseAPDU

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	CardChannel()	Constructs a new CardChannel object.

Method Summary

Modifier and Type	Method	Description
abstract void	close()	Closes this CardChannel.
abstract Card	getCard()	Returns the Card this channel is associated with.
abstract int	getChannelNumber()	Returns the channel number of this CardChannel.
abstract int	transmit(ByteBuffer command, ByteBuffer response)	Transmits the command APDU stored in the command ByteBuffer and receives the response APDU in the response ByteBuffer.
abstract ResponseAPDU	transmit(CommandAPDU command)	Transmits the specified command APDU to the Smart Card and returns the response APDU.

Methods declared in class java.lang.Object

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

Constructor Details

CardChannel

protected CardChannel()

Constructs a new CardChannel object.

This constructor is called by subclasses only. Application should call the Card.getBasicChannel() and Card.openLogicalChannel() methods to obtain a CardChannel object.

Method Details

getCard

public abstract Card getCard()

Returns the Card this channel is associated with.

Returns:

the Card this channel is associated with

getChannelNumber

public abstract int getChannelNumber()

Returns the channel number of this CardChannel. A channel number of 0 indicates the basic logical channel.

Returns:

the channel number of this CardChannel.

Throws:

IllegalStateException - if this channel has been closed or if the corresponding Card has been disconnected.

transmit

public abstract ResponseAPDU transmit(CommandAPDU command)
                               throws CardException

Transmits the specified command APDU to the Smart Card and returns the response APDU.

The CLA byte of the command APDU is automatically adjusted to match the channel number of this CardChannel.

Note that this method cannot be used to transmit MANAGE CHANNEL APDUs. Logical channels should be managed using the Card.openLogicalChannel() and CardChannel.close() methods.

Implementations should transparently handle artifacts of the transmission protocol. For example, when using the T=0 protocol, the following processing should occur as described in ISO/IEC 7816-4:

• if the response APDU has an SW1 of 61, the implementation should issue a GET RESPONSE command using SW2 as the Lefield. This process is repeated as long as an SW1 of 61 is received. The response body of these exchanges is concatenated to form the final response body.

• if the response APDU is 6C XX, the implementation should reissue the command using XX as the Le field.

The ResponseAPDU returned by this method is the result after this processing has been performed.

Parameters:

command - the command APDU

Returns:

the response APDU received from the card

Throws:

IllegalStateException - if this channel has been closed or if the corresponding Card has been disconnected.

IllegalArgumentException - if the APDU encodes a MANAGE CHANNEL command

NullPointerException - if command is null

CardException - if the card operation failed

transmit

public abstract int transmit(ByteBuffer command,
 ByteBuffer response)
                      throws CardException

Transmits the command APDU stored in the command ByteBuffer and receives the response APDU in the response ByteBuffer.

The command buffer must contain valid command APDU data starting at command.position() and the APDU must be command.remaining() bytes long. Upon return, the command buffer's position will be equal to its limit; its limit will not have changed. The output buffer will have received the response APDU bytes. Its position will have advanced by the number of bytes received, which is also the return value of this method.

The CLA byte of the command APDU is automatically adjusted to match the channel number of this CardChannel.

Note that this method cannot be used to transmit MANAGE CHANNEL APDUs. Logical channels should be managed using the Card.openLogicalChannel() and CardChannel.close() methods.

See transmit() for a discussion of the handling of response APDUs with the SW1 values 61 or 6C.

Parameters:

command - the buffer containing the command APDU

response - the buffer that shall receive the response APDU from the card

Returns:

the length of the received response APDU

Throws:

IllegalStateException - if this channel has been closed or if the corresponding Card has been disconnected.

NullPointerException - if command or response is null

ReadOnlyBufferException - if the response buffer is read-only

IllegalArgumentException - if command and response are the same object, if response may not have sufficient space to receive the response APDU or if the APDU encodes a MANAGE CHANNEL command

CardException - if the card operation failed

close

public abstract void close()
                    throws CardException

Closes this CardChannel. The logical channel is closed by issuing a MANAGE CHANNEL command that should use the format [xx 70 80 0n] where n is the channel number of this channel and xx is the CLA byte that encodes this logical channel and has all other bits set to 0. After this method returns, calling other methods in this class will raise an IllegalStateException.

Note that the basic logical channel cannot be closed using this method. It can be closed by calling Card.disconnect(boolean).

Throws:

CardException - if the card operation failed

IllegalStateException - if this CardChannel represents a connection the basic logical channel