org.eclipse.net4j.util.io
Class DelegatingInputStream

java.lang.Object
  java.io.InputStream
      org.eclipse.net4j.util.io.DelegatingInputStream

All Implemented Interfaces:

Closeable

Direct Known Subclasses:

XORInputStream

public class DelegatingInputStream

extends InputStream

A DelegatingInputStream contains some other input stream, which it uses as its basic source of data, possibly transforming the data along the way or providing additional functionality. The class DelegatingInputStream itself simply overrides all (see note below) methods of InputStream with versions that pass all requests to the contained input stream. Subclasses of DelegatingInputStream may further override some of these methods and may also provide additional methods and fields.

Note: The only difference to FilterInputStream is that DelegatingInputStream does not override InputStream.read(byte[]) or InputStream.read(byte[], int, int) but rather exposes the original implementations of InputStream which call read() instead of their delegate counterparts.

in

protected volatile InputStream in

The input stream to be filtered.

DelegatingInputStream

protected DelegatingInputStream(InputStream in)

Creates a DelegatingInputStream by assigning the argument in to the field this.in so as to remember it for later use.

Parameters:

in - the underlying input stream, or null if this instance is to be created without an underlying stream.

getDelegate

public InputStream getDelegate()

read

public int read()
         throws IOException

Reads the next byte of data from this input stream. The value byte is returned as an int in the range 0 to 255. If no byte is available because the end of the stream has been reached, the value -1 is returned. This method blocks until input data is available, the end of the stream is detected, or an exception is thrown.

This method simply performs in.read() and returns the result.

Specified by:

read in class InputStream

Returns:

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

Throws:

IOException - if an I/O error occurs.

See Also:

in

skip

public long skip(long n)
          throws IOException

Skips over and discards n bytes of data from the input stream. The skip method may, for a variety of reasons, end up skipping over some smaller number of bytes, possibly 0. The actual number of bytes skipped is returned.

This method simply performs in.skip(n).

Overrides:

skip in class InputStream

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.

This method simply performs in.available() and returns the result.

Overrides:

available in class InputStream

Returns:

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

Throws:

IOException - if an I/O error occurs.

See Also:

in

close

public void close()
           throws IOException

Closes this input stream and releases any system resources associated with the stream. This method simply performs in.close().

Specified by:

close in interface Closeable

Overrides:

close in class InputStream

Throws:

IOException - if an I/O error occurs.

See Also:

in

mark

public void mark(int readlimit)

Marks the current position in this input stream. A subsequent call to the reset method repositions this stream at the last marked position so that subsequent reads re-read the same bytes.

The readlimit argument tells this input stream to allow that many bytes to be read before the mark position gets invalidated.

This method simply performs in.mark(readlimit).

Overrides:

mark in class InputStream

Parameters:

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

See Also:

in, reset()

reset

public void reset()
           throws IOException

Repositions this stream to the position at the time the mark method was last called on this input stream.

This method simply performs in.reset().

Stream marks are intended to be used in situations where you need to read ahead a little to see what's in the stream. Often this is most easily done by invoking some general parser. If the stream is of the type handled by the parse, it just chugs along happily. If the stream is not of that type, the parser should toss an exception when it fails. If this happens within readlimit bytes, it allows the outer code to reset the stream and try another parser.

Overrides:

reset in class InputStream

Throws:

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

See Also:

in, mark(int)

markSupported

public boolean markSupported()

Tests if this input stream supports the mark and reset methods. This method simply performs in.markSupported().

Overrides:

markSupported in class InputStream

Returns:

true if this stream type supports the mark and reset method; false otherwise.

See Also:

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