com.antelmann.io
Class InterceptInputStream

java.lang.Object
  java.io.InputStream
      com.antelmann.io.InterceptInputStream

All Implemented Interfaces:

Closeable

Direct Known Subclasses:

ReplaceInputStream

public class InterceptInputStream
extends InputStream

A specialized stream that allows to provide custom actions upon the occurrence of a given byte pattern. The custom actions occur through registered Handler objects; bytes can be skipped from the stream (to not have the given pattern occur in the stream) and bytes can be inserted into the stream through given methods. The class may be subclassed to provide more sophisticated pattern matching, as this implementation only acts upon exact matches of a search pattern found.

Author:

Holger Antelmann

See Also:

ReplaceInputStream

Nested Class Summary

static interface

InterceptInputStream.Handler used to handle pattern occurrences for an InterceptInputStream

Constructor Summary

InterceptInputStream(InputStream in, byte[] searchPattern)

Method Summary

void	addHandler(InterceptInputStream.Handler handler)
protected int	checkForMatch(byte[] buffer1, byte[] buffer2, byte[] searchPattern, int cursor) checks whether the exact searchPattern can be found in buffer1 or in the intersection between buffer1 and buffer2.
void	close()
void	insertBytes(byte[] bytes) inserts the given bytes into the stream, so that these bytes are read next before all others that would normally follow at this point.
boolean	markSupported() returns false
int	read()
long	readSoFar() returns the total number of bytes read from the original stream so far (not considering inserted bytes but counting skipped bytes)
void	reset() throws IOException
long	skip(long numberOfBytes) skips bytes only from the source input stream - ignoring inserted bytes

Methods inherited from class java.io.InputStream

available, mark, read, read

Methods inherited from class java.lang.Object

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

Constructor Detail

InterceptInputStream

public InterceptInputStream(InputStream in,
                            byte[] searchPattern)

Method Detail

addHandler

public void addHandler(InterceptInputStream.Handler handler)

close

public void close()
           throws IOException

Specified by:

close in interface Closeable

Overrides:

close in class InputStream

Throws:

IOException

markSupported

public boolean markSupported()

returns false

Overrides:

markSupported in class InputStream

reset

public void reset()
           throws IOException

throws IOException

Overrides:

reset in class InputStream

Throws:

IOException

insertBytes

public void insertBytes(byte[] bytes)

inserts the given bytes into the stream, so that these bytes are read next before all others that would normally follow at this point. The inserted bytes are unchecked in regards to the search pattern.

skip

public long skip(long numberOfBytes)
          throws IOException

skips bytes only from the source input stream - ignoring inserted bytes

Overrides:

skip in class InputStream

Throws:

IOException

read

public int read()
         throws IOException

Specified by:

read in class InputStream

Throws:

IOException

readSoFar

public long readSoFar()

returns the total number of bytes read from the original stream so far (not considering inserted bytes but counting skipped bytes)

checkForMatch

protected int checkForMatch(byte[] buffer1,
                            byte[] buffer2,
                            byte[] searchPattern,
                            int cursor)

checks whether the exact searchPattern can be found in buffer1 or in the intersection between buffer1 and buffer2. May be overwritten to do some more sophisticated pattern matching instead of just testing for an exact match.

Parameters:

buffer1 - byte array containing the current stream buffer

buffer2 - byte array containing the following buffer (to enable pattern search in intersections of two buffers, so that all occurences within the stream can be found)

searchPattern - the pattern that is used for the pattern matching

cursor - the current position of the stream within buffer1

Returns:

the index relative to buffer1 where the first matching pattern begins between the cursor until the end of buffer1 (while considering buffer2 for overlaps) or -1 if no pattern match was found

See Also:

Data.indexOf(byte[], byte[], int, int), (byte[], byte[], byte[])