de.intarsys.tools.randomaccess
Interface IRandomAccess

All Known Implementing Classes:

AbstractRandomAccess, BufferedRandomAccess, RandomAccessByteArray, RandomAccessFile, RandomAccessFilter, RandomAccessViewport

public interface IRandomAccess

An interface for an object that can randomly access bytes in a data stream.

This is an abstraction of RandomAccessFile to support other data storage objects (like byte arrays and so on).

Method Summary

InputStream	asInputStream() A InputStream view on the data structure.
OutputStream	asOutputStream() A OutputStream view on the data structure.
void	close() Closes this random access data container and releases any system resources associated with the stream.
void	flush() Force changes to be made persistent.
long	getLength() Returns the length of this data container.
long	getOffset() Returns the current offset in this data container.
boolean	isReadOnly() true if this is a read only data container.
void	mark() Mark the current offset into the data in a stack like manner.
int	read() Reads a byte of data from this data container.
int	read(byte[] buffer) Reads up to buffer.length bytes of data from this data container into an array of bytes.
int	read(byte[] buffer, int start, int numBytes) Reads up to len bytes of data from this data container into an array of bytes.
void	reset() Reset to the last position on the mark-stack.
void	seek(long offset) Sets the offset, measured from the beginning of the data container at which the next read or write occurs.
void	seekBy(long delta) Sets the offset, measured from the current offset at which the next read or write occurs.
void	setLength(long newLength) Assign the length.
void	write(byte[] buffer) Writes b.length bytes from the specified byte array, starting at the current offset.
void	write(byte[] buffer, int start, int numBytes) Writes len bytes from the specified byte array starting at start.
void	write(int b) Writes the specified byte .

Method Detail

seek

void seek(long offset)
          throws IOException

Sets the offset, measured from the beginning of the data container at which the next read or write occurs. The offset may be set beyond the end of the data container. Setting the offset beyond the end of the data container does not change the data container length. The length will change only by writing after the offset has been set beyond the end of the data container.

Parameters:

offset - the offset position, measured in bytes from the beginning of the data container

Throws:

IOException - if offset is less than 0 or if an I/O error occurs.

seekBy

void seekBy(long delta)
            throws IOException

Sets the offset, measured from the current offset at which the next read or write occurs. The offset may be set beyond the end of the data container. Setting the offset beyond the end of the data container does not change the data container length. The length will change only by writing after the offset has been set beyond the end of the data container.

Parameters:

delta - the ammount of bytes by wich to change the current offset position

Throws:

IOException - if the resulting offset is less than 0 or if an I/O error occurs.

read

int read()
         throws IOException

Reads a byte of data from this data container. The byte is returned as an integer in the range 0 to 255 (0x00-0x0ff). This method blocks if no input is yet available.

This method behaves in exactly the same way as the InputStream.read() method of InputStream.

Returns:

the next byte of data, or -1 if the end of the data container has been reached.

Throws:

IOException - if an I/O error occurs. Not thrown if the end of the data container has been reached.

getOffset

long getOffset()
               throws IOException

Returns the current offset in this data container.

Returns:

the offset from the beginning of the data container, in bytes, at which the next read or write occurs.

Throws:

IOException - if an I/O error occurs.

getLength

long getLength()
               throws IOException

Returns the length of this data container.

Returns:

the length of this data container, measured in bytes.

Throws:

IOException - if an I/O error occurs.

setLength

void setLength(long newLength)
               throws IOException

Assign the length. All bytes after length are truncated. If the real length is currently less than newLength, the data structure will be enlarged.

Parameters:

newLength -

Throws:

IOException

read

int read(byte[] buffer)
         throws IOException

Reads up to buffer.length bytes of data from this data container into an array of bytes. This method blocks until at least one byte of input is available.

This method behaves in the exactly the same way as the InputStream.read(byte[]) method of InputStream.

Parameters:

buffer - the buffer into which the data is read.

Returns:

the total number of bytes read into the buffer, or -1 if there is no more data because the end of this data container has been reached.

Throws:

IOException - if an I/O error occurs.

read

int read(byte[] buffer,
         int start,
         int numBytes)
         throws IOException

Reads up to len bytes of data from this data container into an array of bytes. This method blocks until at least one byte of input is available.

Parameters:

b - the buffer into which the data is read.

off - the start offset of the data.

len - the maximum number of bytes read.

Returns:

the total number of bytes read into the buffer, or -1 if there is no more data because the end of the file has been reached.

Throws:

IOException - if an I/O error occurs.

close

void close()
           throws IOException

Closes this random access data container and releases any system resources associated with the stream. A closed random access data container cannot perform input or output operations and cannot be reopened.

Throws:

IOException - if an I/O error occurs.

flush

void flush()
           throws IOException

Force changes to be made persistent.

Throws:

IOException

isReadOnly

boolean isReadOnly()

true if this is a read only data container.

Returns:

true if this is a read only data container.

write

void write(int b)
           throws IOException

Writes the specified byte . The write starts at the current offset.

Parameters:

b - the byte to be written.

Throws:

IOException - if an I/O error occurs.

write

void write(byte[] buffer)
           throws IOException

Writes b.length bytes from the specified byte array, starting at the current offset.

Parameters:

b - the data.

Throws:

IOException - if an I/O error occurs.

write

void write(byte[] buffer,
           int start,
           int numBytes)
           throws IOException

Writes len bytes from the specified byte array starting at start.

Parameters:

buffer - the data.

start - the start offset in the data.

numBytes - the number of bytes to write.

Throws:

IOException - if an I/O error occurs.

asInputStream

InputStream asInputStream()

A InputStream view on the data structure.

Returns:

A InputStream view on the data structure.

asOutputStream

OutputStream asOutputStream()

A OutputStream view on the data structure.

Returns:

A OutputStream view on the data structure.

mark

void mark()
          throws IOException

Mark the current offset into the data in a stack like manner.

Throws:

IOException

reset

void reset()
           throws IOException

Reset to the last position on the mark-stack.

Throws:

IOException