org.jwall.log.io

Class SequentialFileInputStream

java.lang.Object

java.io.InputStream

org.jwall.log.io.SequentialFileInputStream

All Implemented Interfaces:

Closeable, AutoCloseable

public class SequentialFileInputStream
extends InputStream

This class implements an input stream that will read from a sequence of files. It is intended to provide the opposite of a split of files into parts. Each part is read in chronological order.

At the end, the stream waits for new data to be appended to the last file, or a new file to be created that matches the names.

Author:

Christian Bockermann <chris@jwall.org>

Constructor Summary

Constructors

Constructor and Description
SequentialFileInputStream(File file) Creates a new SequentialInputStream, which will read the specified file and any subsequent files that match the file's name, possibly and a appended number, i.e. for the file /tmp/test.log the stream will read /tmp/test.log /tmp/test.log.1 /tmp/test.log.2 ...
SequentialFileInputStream(File file, boolean removeAfterRead) This creates a SequentialInputStream which will remove any files that have completeley been read (i.e. they have been processed until EOF and another, newer file matching the pattern does exist).
SequentialFileInputStream(File file, String pattern, boolean removeAfterRead)

Method Summary

Methods

Modifier and Type	Method and Description
int	available()
protected boolean	hasNext() This method checks if there exists a next file in the sequence.
static void	main(String[] args)
boolean	markSupported()
boolean	matchesSequence(File f)
protected void	openNextFile() This method closes the current file an opens the next file in the sequence.
int	read() This read method is basically a read of the current open file.

Methods inherited from class java.io.InputStream

close, mark, read, read, reset, skip

Methods inherited from class java.lang.Object

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

Constructor Detail

SequentialFileInputStream

public SequentialFileInputStream(File file)
                          throws IOException

Creates a new SequentialInputStream, which will read the specified file and any subsequent files that match the file's name, possibly and a appended number, i.e. for the file /tmp/test.log the stream will read

    /tmp/test.log
    /tmp/test.log.1
    /tmp/test.log.2
    ...
 

The trailing digits may as well be time-stamps or the like. The files are read in order of their last-modification-time.

Parameters:

file - The initial file.

Throws:

IOException

SequentialFileInputStream

public SequentialFileInputStream(File file,
                         boolean removeAfterRead)
                          throws IOException

This creates a SequentialInputStream which will remove any files that have completeley been read (i.e. they have been processed until EOF and another, newer file matching the pattern does exist).

Whether the old files are to be removed is determined by the removeAfterRead flag.

Parameters:

file - The initial file to start with.

removeAfterRead - Whether the old files should be removed or not.

Throws:

IOException

SequentialFileInputStream

public SequentialFileInputStream(File file,
                         String pattern,
                         boolean removeAfterRead)
                          throws IOException

Throws:

IOException

Method Detail

matchesSequence

public boolean matchesSequence(File f)

hasNext

protected boolean hasNext()

This method checks if there exists a next file in the sequence.

Returns:

true if a new file exists, which may indicate that the current file is finished.

openNextFile

protected void openNextFile()
                     throws IOException

This method closes the current file an opens the next file in the sequence. If no next file exists, this method will block until one has been created.

Throws:

IOException

read

public int read()
         throws IOException

This read method is basically a read of the current open file. It will block if there is no more data and no new file exists.

Specified by:

read in class InputStream

Throws:

IOException

See Also:

InputStream.read()

markSupported

public boolean markSupported()

Overrides:

markSupported in class InputStream

See Also:

InputStream.markSupported()

available

public int available()
              throws IOException

Overrides:

available in class InputStream

Throws:

IOException

See Also:

InputStream.available()

main

public static void main(String[] args)
                 throws Exception

Throws:

Exception