de.intarsys.tools.randomaccess
Class RandomAccessViewport

java.lang.Object
  de.intarsys.tools.randomaccess.AbstractRandomAccess
      de.intarsys.tools.randomaccess.RandomAccessFilter
          de.intarsys.tools.randomaccess.RandomAccessViewport

All Implemented Interfaces:

IRandomAccess

public class RandomAccessViewport
extends RandomAccessFilter

A viewport in an existing IRandomAccess.

Constructor Summary

RandomAccessViewport(IRandomAccess ra, long offset, long length)
Create a viewport to the existing IRandomAccess ra.

Method Summary

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.
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	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 .

Methods inherited from class de.intarsys.tools.randomaccess.RandomAccessFilter

close, flush

Methods inherited from class de.intarsys.tools.randomaccess.AbstractRandomAccess

asInputStream, asOutputStream, mark, reset

Methods inherited from class java.lang.Object

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

Constructor Detail

RandomAccessViewport

public RandomAccessViewport(IRandomAccess ra,
                            long offset,
                            long length)
                     throws IOException

Create a viewport to the existing IRandomAccess ra.

ATTENTION: This will not seek to offset in ra. This means after creation before initial use you have to position the IRandomAccess yourself using seek.

Parameters:

ra -

offset -

length -

Throws:

IOException

Method Detail

getLength

public long getLength()
               throws IOException

Description copied from interface: IRandomAccess

Returns the length of this data container.

Specified by:

getLength in interface IRandomAccess

Overrides:

getLength in class RandomAccessFilter

Returns:

the length of this data container, measured in bytes.

Throws:

IOException - if an I/O error occurs.

getOffset

public long getOffset()
               throws IOException

Description copied from interface: IRandomAccess

Returns the current offset in this data container.

Specified by:

getOffset in interface IRandomAccess

Overrides:

getOffset in class RandomAccessFilter

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.

isReadOnly

public boolean isReadOnly()

Description copied from interface: IRandomAccess

true if this is a read only data container.

Specified by:

isReadOnly in interface IRandomAccess

Overrides:

isReadOnly in class RandomAccessFilter

Returns:

true if this is a read only data container.

read

public int read()
         throws IOException

Description copied from interface: IRandomAccess

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.

Specified by:

read in interface IRandomAccess

Overrides:

read in class RandomAccessFilter

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.

read

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

Description copied from interface: IRandomAccess

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.

Specified by:

read in interface IRandomAccess

Overrides:

read in class RandomAccessFilter

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.

read

public int read(byte[] buffer)
         throws IOException

Description copied from interface: IRandomAccess

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.

Specified by:

read in interface IRandomAccess

Overrides:

read in class RandomAccessFilter

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.

seek

public void seek(long offset)
          throws IOException

Description copied from interface: IRandomAccess

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.

Specified by:

seek in interface IRandomAccess

Overrides:

seek in class RandomAccessFilter

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

public void seekBy(long delta)
            throws IOException

Description copied from interface: IRandomAccess

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.

Specified by:

seekBy in interface IRandomAccess

Overrides:

seekBy in class RandomAccessFilter

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.

setLength

public void setLength(long newLength)
               throws IOException

Description copied from interface: IRandomAccess

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

Specified by:

setLength in interface IRandomAccess

Overrides:

setLength in class RandomAccessFilter

Throws:

IOException

write

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

Description copied from interface: IRandomAccess

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

Specified by:

write in interface IRandomAccess

Overrides:

write in class RandomAccessFilter

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.

write

public void write(byte[] buffer)
           throws IOException

Description copied from interface: IRandomAccess

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

Specified by:

write in interface IRandomAccess

Overrides:

write in class RandomAccessFilter

Throws:

IOException - if an I/O error occurs.

write

public void write(int b)
           throws IOException

Description copied from interface: IRandomAccess

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

Specified by:

write in interface IRandomAccess

Overrides:

write in class RandomAccessFilter

Parameters:

b - the byte to be written.

Throws:

IOException - if an I/O error occurs.