org.apache.tika.io

Class LookaheadInputStream

java.lang.Object

java.io.InputStream

org.apache.tika.io.LookaheadInputStream

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable

public class LookaheadInputStream
extends java.io.InputStream

Stream wrapper that make it easy to read up to n bytes ahead from a stream that supports the mark feature. This class insulates the underlying stream from things like possible mark(), reset() and close() calls by external components that might otherwise invalidate the marked state of a stream.

The recommended usage pattern of this class is:

     try (InputStream lookahead = new LookaheadInputStream(stream, n)) {
         processStream(lookahead);
     }
 

This usage pattern guarantees that only up to n bytes from the original stream can ever be read, and that the stream will have been marked and then reset to its original state once the above code block exits. No code in the fictional processStream() method can affect the the state of the original stream.

Since:

Apache Tika 0.10

Field Summary

Fields

Modifier and Type	Field and Description
private byte[]	buffer
private int	buffered
private int	mark
private int	position
private java.io.InputStream	stream

Constructor Summary

Constructors

Constructor and Description
LookaheadInputStream(java.io.InputStream stream, int n) Creates a lookahead wrapper for the given input stream.

Method Summary

Modifier and Type	Method and Description
int	available()
void	close()
private void	fill()
void	mark(int readlimit)
boolean	markSupported()
int	read()
int	read(byte[] b, int off, int len)
void	reset()
long	skip(long n)

Methods inherited from class java.io.InputStream

read

Methods inherited from class java.lang.Object

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

Field Detail

stream

private java.io.InputStream stream

buffer

private final byte[] buffer

buffered

private int buffered

position

private int position

mark

private int mark

Constructor Detail

LookaheadInputStream

public LookaheadInputStream(java.io.InputStream stream,
                            int n)

Creates a lookahead wrapper for the given input stream. The given input stream should support the mark feature, as otherwise the state of that stream will be undefined after the lookahead wrapper has been closed. As a special case a null stream is treated as an empty stream.

Parameters:

stream - input stream, can be null

n - maximum number of bytes to look ahead

Method Detail

close

public void close()
           throws java.io.IOException

Specified by:

close in interface java.io.Closeable

Specified by:

close in interface java.lang.AutoCloseable

Overrides:

close in class java.io.InputStream

Throws:

java.io.IOException

fill

private void fill()
           throws java.io.IOException

Throws:

java.io.IOException

read

public int read()
         throws java.io.IOException

Specified by:

read in class java.io.InputStream

Throws:

java.io.IOException

read

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

Overrides:

read in class java.io.InputStream

Throws:

java.io.IOException

skip

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

Overrides:

skip in class java.io.InputStream

Throws:

java.io.IOException

available

public int available()

Overrides:

available in class java.io.InputStream

markSupported

public boolean markSupported()

Overrides:

markSupported in class java.io.InputStream

mark

public void mark(int readlimit)

Overrides:

mark in class java.io.InputStream

reset

public void reset()

Overrides:

reset in class java.io.InputStream