API java : SharedFileInputStream

javax.mail.util
Class SharedFileInputStream

java.lang.Object
  java.io.InputStream
      java.io.FilterInputStream
          java.io.BufferedInputStream
              javax.mail.util.SharedFileInputStream

All Implemented Interfaces:

Closeable, SharedInputStream

public class SharedFileInputStream
extends BufferedInputStream
implements SharedInputStream

A SharedFileInputStream is a BufferedInputStream that buffers data from the file and supports the mark and reset methods. It also supports the newStream method that allows you to create other streams that represent subsets of the file. A RandomAccessFile object is used to access the file data.

Note that when the SharedFileInputStream is closed, all streams created with the newStream method are also closed. This allows the creator of the SharedFileInputStream object to control access to the underlying file and ensure that it is closed when needed, to avoid leaking file descriptors. Note also that this behavior contradicts the requirements of SharedInputStream and may change in a future release.

Since:

JavaMail 1.4

Author:

Bill Shannon

Field Summary
protected  long	bufpos           The file offset that corresponds to the first byte in the read buffer.
protected  int	bufsize           The normal size of the read buffer.
protected  long	datalen           The amount of data in this subset of the file.
protected  RandomAccessFile	in           The file containing the data.
protected  long	start           The file offset of the start of data in this subset of the file.

 

Fields inherited from class java.io.BufferedInputStream
buf, count, marklimit, markpos, pos

 

Constructor Summary
SharedFileInputStream(File file)           Creates a SharedFileInputStream for the file.
SharedFileInputStream(File file, int size)           Creates a SharedFileInputStream with the specified buffer size.
SharedFileInputStream(String file)           Creates a SharedFileInputStream for the named file
SharedFileInputStream(String file, int size)           Creates a SharedFileInputStream with the specified buffer size.

 

Method Summary
int	available()           Returns the number of bytes that can be read from this input stream without blocking.
void	close()           Closes this input stream and releases any system resources associated with the stream.
protected  void	finalize()           Force this stream to close.
long	getPosition()           Return the current position in the InputStream, as an offset from the beginning of the InputStream.
void	mark(int readlimit)           See the general contract of the mark method of InputStream.
boolean	markSupported()           Tests if this input stream supports the mark and reset methods.
InputStream	newStream(long start, long end)           Return a new InputStream representing a subset of the data from this InputStream, starting at start (inclusive) up to end (exclusive).
int	read()           See the general contract of the read method of InputStream.
int	read(byte[] b, int off, int len)           Reads bytes from this stream into the specified byte array, starting at the given offset.
void	reset()           See the general contract of the reset method of InputStream.
long	skip(long n)           See the general contract of the skip method of InputStream.

 

Methods inherited from class java.io.FilterInputStream
read

 

Methods inherited from class java.lang.Object
clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

 

Field Detail

in

protected RandomAccessFile in

The file containing the data. Shared by all related SharedFileInputStreams.

bufsize

protected int bufsize

The normal size of the read buffer.

bufpos

protected long bufpos

The file offset that corresponds to the first byte in the read buffer.

start

protected long start

The file offset of the start of data in this subset of the file.

datalen

protected long datalen

The amount of data in this subset of the file.

SharedFileInputStream

public SharedFileInputStream(File file)
                      throws IOException

Creates a SharedFileInputStream for the file.

Parameters:

file - the file

Throws:

IOException

SharedFileInputStream

public SharedFileInputStream(String file)
                      throws IOException

Creates a SharedFileInputStream for the named file

Parameters:

file - the file

Throws:

IOException

SharedFileInputStream

public SharedFileInputStream(File file,
                             int size)
                      throws IOException

Creates a SharedFileInputStream with the specified buffer size.

Parameters:

file - the file

size - the buffer size.

Throws:

IllegalArgumentException - if size <= 0.

IOException

SharedFileInputStream

public SharedFileInputStream(String file,
                             int size)
                      throws IOException

Creates a SharedFileInputStream with the specified buffer size.

Parameters:

file - the file

size - the buffer size.

Throws:

IllegalArgumentException - if size <= 0.

IOException

read

public int read()
         throws IOException

See the general contract of the read method of InputStream.

Overrides:

read in class BufferedInputStream

Returns:

the next byte of data, or -1 if the end of the stream is reached.

Throws:

IOException - if an I/O error occurs.

read

public int read(byte[] b,
                int off,
                int len)
         throws IOException

Reads bytes from this stream into the specified byte array, starting at the given offset.

This method implements the general contract of the corresponding read method of the InputStream class.

Overrides:

read in class BufferedInputStream

Parameters:

b - destination buffer.

off - offset at which to start storing bytes.

len - maximum number of bytes to read.

Returns:

the number of bytes read, or -1 if the end of the stream has been reached.

Throws:

IOException - if an I/O error occurs.

skip

public long skip(long n)
          throws IOException

See the general contract of the skip method of InputStream.

Overrides:

skip in class BufferedInputStream

Parameters:

n - the number of bytes to be skipped.

Returns:

the actual number of bytes skipped.

Throws:

IOException - if an I/O error occurs.

available

public int available()
              throws IOException

Returns the number of bytes that can be read from this input stream without blocking.

Overrides:

available in class BufferedInputStream

Returns:

the number of bytes that can be read from this input stream without blocking.

Throws:

IOException - if an I/O error occurs.

mark

public void mark(int readlimit)

See the general contract of the mark method of InputStream.

Overrides:

mark in class BufferedInputStream

Parameters:

readlimit - the maximum limit of bytes that can be read before the mark position becomes invalid.

See Also:

reset()

reset

public void reset()
           throws IOException

See the general contract of the reset method of InputStream.

If markpos is -1 (no mark has been set or the mark has been invalidated), an IOException is thrown. Otherwise, pos is set equal to markpos.

Overrides:

reset in class BufferedInputStream

Throws:

IOException - if this stream has not been marked or if the mark has been invalidated.

See Also:

mark(int)

markSupported

public boolean markSupported()

Tests if this input stream supports the mark and reset methods. The markSupported method of SharedFileInputStream returns true.

Overrides:

markSupported in class BufferedInputStream

Returns:

a boolean indicating if this stream type supports the mark and reset methods.

See Also:

InputStream.mark(int), InputStream.reset()

close

public void close()
           throws IOException

Closes this input stream and releases any system resources associated with the stream.

Specified by:

close in interface Closeable

Overrides:

close in class BufferedInputStream

Throws:

IOException - if an I/O error occurs.

getPosition

public long getPosition()

Return the current position in the InputStream, as an offset from the beginning of the InputStream.

Specified by:

getPosition in interface SharedInputStream

Returns:

the current position

newStream

public InputStream newStream(long start,
                             long end)

Return a new InputStream representing a subset of the data from this InputStream, starting at start (inclusive) up to end (exclusive). start must be non-negative. If end is -1, the new stream ends at the same place as this stream. The returned InputStream will also implement the SharedInputStream interface.

Specified by:

newStream in interface SharedInputStream

Parameters:

start - the starting position

end - the ending position + 1

Returns:

the new stream

finalize

protected void finalize()
                 throws Throwable

Force this stream to close.

Overrides:

finalize in class Object

Throws:

Throwable