Package javax.mail.util

Class SharedFileInputStream

java.lang.Object

java.io.InputStream

java.io.FilterInputStream

java.io.BufferedInputStream

javax.mail.util.SharedFileInputStream

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable, SharedInputStream

Direct Known Subclasses:

WritableSharedFile

public class SharedFileInputStream
extends java.io.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

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
(package private) static class	SharedFileInputStream.SharedFile	A shared class that keeps track of the references to a particular file so it can be closed when the last reference is gone.

Field Summary

Fields

Modifier and Type	Field	Description
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.
private static int	defaultBufferSize
protected java.io.RandomAccessFile	in	The file containing the data.
private boolean	master	True if this is a top level stream created directly by "new".
private SharedFileInputStream.SharedFile	sf
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

Constructors

Modifier	Constructor	Description
	SharedFileInputStream(java.io.File file)	Creates a SharedFileInputStream for the file.
	SharedFileInputStream(java.io.File file, int size)	Creates a SharedFileInputStream with the specified buffer size.
	SharedFileInputStream(java.lang.String file)	Creates a SharedFileInputStream for the named file
	SharedFileInputStream(java.lang.String file, int size)	Creates a SharedFileInputStream with the specified buffer size.
private	SharedFileInputStream(SharedFileInputStream.SharedFile sf, long start, long len, int bufsize)	Used internally by the newStream method.

Method Summary

Modifier and Type	Method	Description
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.
private void	ensureOpen()	Check to make sure that this stream has not been closed
private void	fill()	Fills the buffer with more data, taking into account shuffling and other tricks for dealing with marks.
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.
private int	in_available()
private void	init(SharedFileInputStream.SharedFile sf, int size)
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.
java.io.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.
private int	read1(byte[] b, int off, int len)	Read characters into a portion of an array, reading from the underlying stream at most once if necessary.
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.io.InputStream

nullInputStream, readAllBytes, readNBytes, readNBytes, transferTo

Methods inherited from class java.lang.Object

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

Field Detail

defaultBufferSize

private static int defaultBufferSize

in

protected java.io.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.

master

private boolean master

True if this is a top level stream created directly by "new". False if this is a derived stream created by newStream.

sf

private SharedFileInputStream.SharedFile sf

Constructor Detail

SharedFileInputStream

public SharedFileInputStream(java.io.File file)
                      throws java.io.IOException

Creates a SharedFileInputStream for the file.

Parameters:

file - the file

Throws:

java.io.IOException - for errors opening the file

SharedFileInputStream

public SharedFileInputStream(java.lang.String file)
                      throws java.io.IOException

Creates a SharedFileInputStream for the named file

Parameters:

file - the file

Throws:

java.io.IOException - for errors opening the file

SharedFileInputStream

public SharedFileInputStream(java.io.File file,
                             int size)
                      throws java.io.IOException

Creates a SharedFileInputStream with the specified buffer size.

Parameters:

file - the file

size - the buffer size.

Throws:

java.io.IOException - for errors opening the file

java.lang.IllegalArgumentException - if size ≤ 0.

SharedFileInputStream

public SharedFileInputStream(java.lang.String file,
                             int size)
                      throws java.io.IOException

Creates a SharedFileInputStream with the specified buffer size.

Parameters:

file - the file

size - the buffer size.

Throws:

java.io.IOException - for errors opening the file

java.lang.IllegalArgumentException - if size ≤ 0.

SharedFileInputStream

private SharedFileInputStream(SharedFileInputStream.SharedFile sf,
                              long start,
                              long len,
                              int bufsize)

Used internally by the newStream method.

Method Detail

ensureOpen

private void ensureOpen()
                 throws java.io.IOException

Check to make sure that this stream has not been closed

Throws:

java.io.IOException

init

private void init(SharedFileInputStream.SharedFile sf,
                  int size)
           throws java.io.IOException

Throws:

java.io.IOException

fill

private void fill()
           throws java.io.IOException

Fills the buffer with more data, taking into account shuffling and other tricks for dealing with marks. Assumes that it is being called by a synchronized method. This method also assumes that all data has already been read in, hence pos > count.

Throws:

java.io.IOException

read

public int read()
         throws java.io.IOException

See the general contract of the read method of InputStream.

Overrides:

read in class java.io.BufferedInputStream

Returns:

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

Throws:

java.io.IOException - if an I/O error occurs.

read1

private int read1(byte[] b,
                  int off,
                  int len)
           throws java.io.IOException

Read characters into a portion of an array, reading from the underlying stream at most once if necessary.

Throws:

java.io.IOException

read

public int read(byte[] b,
                int off,
                int len)
         throws java.io.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 java.io.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:

java.io.IOException - if an I/O error occurs.

skip

public long skip(long n)
          throws java.io.IOException

See the general contract of the skip method of InputStream.

Overrides:

skip in class java.io.BufferedInputStream

Parameters:

n - the number of bytes to be skipped.

Returns:

the actual number of bytes skipped.

Throws:

java.io.IOException - if an I/O error occurs.

available

public int available()
              throws java.io.IOException

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

Overrides:

available in class java.io.BufferedInputStream

Returns:

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

Throws:

java.io.IOException - if an I/O error occurs.

in_available

private int in_available()
                  throws java.io.IOException

Throws:

java.io.IOException

mark

public void mark(int readlimit)

See the general contract of the mark method of InputStream.

Overrides:

mark in class java.io.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 java.io.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 java.io.BufferedInputStream

Throws:

java.io.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 java.io.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 java.io.IOException

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

Specified by:

close in interface java.lang.AutoCloseable

Specified by:

close in interface java.io.Closeable

Overrides:

close in class java.io.BufferedInputStream

Throws:

java.io.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 java.io.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 java.lang.Throwable

Force this stream to close.

Overrides:

finalize in class java.lang.Object

Throws:

java.lang.Throwable