opencard.opt.iso.fs
Interface CardFileInfo
- All Known Implementing Classes:
- CardFile
- public abstract interface CardFileInfo
Provides information about the structure of a file.
File information is obtained from the smartcard by selecting
a file. The file may be a dedicated file (DF, also referred to as
directory) or an elementary file (EF). The smartcard typically responds
with the selected file's header.
Unlike the select command itself, the file header is not subject to
standards, so it cannot be encapsulated in a predefined class. This
interface defines some methods that should be implementable regardless
of the particular card and it's select response. Most of these methods
provide information about the structure of an elementary file.
The comments to the methods required by this interface assume knowledge
of the file types defined by ISO 7816. Some information about these file
types can be found in the comments to FileAccessCardService.
The term the file, which is frequently used in the comments,
refers to the file on the smartcard for which an instance of this
interface provides information.
- See Also:
FileAccessCardService
Method Summary |
short |
getFileID()
Returns the identifier of the file.
|
byte[] |
getHeader()
Returns the file header.
|
int |
getLength()
Returns the length of the file.
|
int |
getRecordSize()
Returns the record size of the file.
|
boolean |
isCyclic()
Tests whether the file is a cyclic file.
|
boolean |
isDirectory()
Tests whether the file is a DF. |
boolean |
isTransparent()
Tests whether the file is a transparent file.
|
boolean |
isVariable()
Tests whether the file is a variable record file.
|
getFileID
public short getFileID()
- Returns the identifier of the file.
It is most likely that this method is of no particular use, but since
the file identifier is the most basic information about a file at all,
it is included here anyway.
- Returns:
- the identifier of the file
isDirectory
public boolean isDirectory()
- Tests whether the file is a DF.
- Returns:
- true if the file is a DF, false otherwise
isTransparent
public boolean isTransparent()
- Tests whether the file is a transparent file.
The value returned is valid only if the file is not a DF,
that is if isDirectory returns false.
- Returns:
- true if the file is a transparent file
- See Also:
isDirectory()
isCyclic
public boolean isCyclic()
- Tests whether the file is a cyclic file.
The value returned is valid only if the file is not a DF and not a
transparent file, that is if isDirectory as well as
isTransparent return false.
- Returns:
- true if the file is a cyclic file
- See Also:
isDirectory()
,
isTransparent()
isVariable
public boolean isVariable()
- Tests whether the file is a variable record file.
The value returned is valid only if the file is not a DF and not a
transparent file, that is if isDirectory as well as
isTransparent return false.
- Returns:
- true if the file is a structured file with
variable record size
- See Also:
isDirectory()
,
isTransparent()
getLength
public int getLength()
- Returns the length of the file.
If the file is a transparent file, that is if isDirectory
returns false and isTransparent returns true,
this method returns the number of bytes in the file.
If the file is a structured file with fixed record length, either
cyclic or non-cyclic, this method returns also returns the number
of bytes in the file, that is the size of a record multiplied by
the number of bytes in a record.
If the file is a DF, a structured file with variable record length,
or some card specific file type, the value returned by this method
is implementation dependent.
- Returns:
- the number of bytes in the file
- See Also:
isDirectory()
,
isTransparent()
getRecordSize
public int getRecordSize()
- Returns the record size of the file.
The value returned is valid only if the file is a structured file
with fixed record size, that is if isDirectory,
isTransparent and isVariable return false.
- Returns:
- the size of a record of the file
- See Also:
isDirectory()
,
isTransparent()
,
isVariable()
getHeader
public byte[] getHeader()
- Returns the file header.
This method actually returns the smartcard's response (or expected
response) to a selection of the file. For an EF, this is the file
header which may have been expanded by some application data, if
the card OS allows to do so. For a DF, this is the file header,
also optionally expanded, or some other data that has been defined
as the select response for the DF. The EMV standard requires the
select response for a DF to be defineable by applications.
This method is not invoked by the OpenCard Framework, and it is
not yet clear whether it will be useful for applications. However,
removing a method from this interface will be easier than adding
it later, so it is currently required. File services that do not
want to support this method may simply return null.
- Returns:
- the smartcard's response to a selection of the file,
or null if not supported