org.apache.commons.io.input
Class ProxyInputStream

java.lang.Object
  java.io.InputStream
      java.io.FilterInputStream
          org.apache.commons.io.input.ProxyInputStream

All Implemented Interfaces:

Closeable

Direct Known Subclasses:

AutoCloseInputStream, BOMInputStream, CloseShieldInputStream, CountingInputStream, SwappedDataInputStream, TaggedInputStream, TeeInputStream

public abstract class ProxyInputStream
extends FilterInputStream

A Proxy stream which acts as expected, that is it passes the method calls on to the proxied stream and doesn't change which methods are being called.

It is an alternative base class to FilterInputStream to increase reusability, because FilterInputStream changes the methods being called, such as read(byte[]) to read(byte[], int, int).

See the protected methods for ways in which a subclass can easily decorate a stream with custom pre-, post- or error processing functionality.

Version:

$Id: ProxyInputStream.java 1304052 2012-03-22 20:55:29Z ggregory $

Field Summary

Fields inherited from class java.io.FilterInputStream

in

Constructor Summary

ProxyInputStream(InputStream proxy)
Constructs a new ProxyInputStream.

Method Summary

protected void	afterRead(int n) Invoked by the read methods after the proxied call has returned successfully.
int	available() Invokes the delegate's available() method.
protected void	beforeRead(int n) Invoked by the read methods before the call is proxied.
void	close() Invokes the delegate's close() method.
protected void	handleIOException(IOException e) Handle any IOExceptions thrown.
void	mark(int readlimit) Invokes the delegate's mark(int) method.
boolean	markSupported() Invokes the delegate's markSupported() method.
int	read() Invokes the delegate's read() method.
int	read(byte[] bts) Invokes the delegate's read(byte[]) method.
int	read(byte[] bts, int off, int len) Invokes the delegate's read(byte[], int, int) method.
void	reset() Invokes the delegate's reset() method.
long	skip(long ln) Invokes the delegate's skip(long) method.

Methods inherited from class java.lang.Object

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

Constructor Detail

ProxyInputStream

public ProxyInputStream(InputStream proxy)

Constructs a new ProxyInputStream.

Parameters:

proxy - the InputStream to delegate to

Method Detail

read

public int read()
         throws IOException

Invokes the delegate's read() method.

Overrides:

read in class FilterInputStream

Returns:

the byte read or -1 if the end of stream

Throws:

IOException - if an I/O error occurs

read

public int read(byte[] bts)
         throws IOException

Invokes the delegate's read(byte[]) method.

Overrides:

read in class FilterInputStream

Parameters:

bts - the buffer to read the bytes into

Returns:

the number of bytes read or -1 if the end of stream

Throws:

IOException - if an I/O error occurs

read

public int read(byte[] bts,
                int off,
                int len)
         throws IOException

Invokes the delegate's read(byte[], int, int) method.

Overrides:

read in class FilterInputStream

Parameters:

bts - the buffer to read the bytes into

off - The start offset

len - The number of bytes to read

Returns:

the number of bytes read or -1 if the end of stream

Throws:

IOException - if an I/O error occurs

skip

public long skip(long ln)
          throws IOException

Invokes the delegate's skip(long) method.

Overrides:

skip in class FilterInputStream

Parameters:

ln - the number of bytes to skip

Returns:

the actual number of bytes skipped

Throws:

IOException - if an I/O error occurs

available

public int available()
              throws IOException

Invokes the delegate's available() method.

Overrides:

available in class FilterInputStream

Returns:

the number of available bytes

Throws:

IOException - if an I/O error occurs

close

public void close()
           throws IOException

Invokes the delegate's close() method.

Specified by:

close in interface Closeable

Overrides:

close in class FilterInputStream

Throws:

IOException - if an I/O error occurs

mark

public void mark(int readlimit)

Invokes the delegate's mark(int) method.

Overrides:

mark in class FilterInputStream

Parameters:

readlimit - read ahead limit

reset

public void reset()
           throws IOException

Invokes the delegate's reset() method.

Overrides:

reset in class FilterInputStream

Throws:

IOException - if an I/O error occurs

markSupported

public boolean markSupported()

Invokes the delegate's markSupported() method.

Overrides:

markSupported in class FilterInputStream

Returns:

true if mark is supported, otherwise false

beforeRead

protected void beforeRead(int n)
                   throws IOException

Invoked by the read methods before the call is proxied. The number of bytes that the caller wanted to read (1 for the read() method, buffer length for read(byte[]), etc.) is given as an argument.

Subclasses can override this method to add common pre-processing functionality without having to override all the read methods. The default implementation does nothing.

Note this method is not called from skip(long) or reset(). You need to explicitly override those methods if you want to add pre-processing steps also to them.

Parameters:

n - number of bytes that the caller asked to be read

Throws:

IOException - if the pre-processing fails

Since:

2.0

afterRead

protected void afterRead(int n)
                  throws IOException

Invoked by the read methods after the proxied call has returned successfully. The number of bytes returned to the caller (or -1 if the end of stream was reached) is given as an argument.

Subclasses can override this method to add common post-processing functionality without having to override all the read methods. The default implementation does nothing.

Note this method is not called from skip(long) or reset(). You need to explicitly override those methods if you want to add post-processing steps also to them.

Parameters:

n - number of bytes read, or -1 if the end of stream was reached

Throws:

IOException - if the post-processing fails

Since:

2.0

handleIOException

protected void handleIOException(IOException e)
                          throws IOException

Handle any IOExceptions thrown.

This method provides a point to implement custom exception handling. The default behaviour is to re-throw the exception.

Parameters:

e - The IOException thrown

Throws:

IOException - if an I/O error occurs

Since:

2.0