org.apache.commons.io.input
Class ProxyReader

java.lang.Object
  java.io.Reader
      java.io.FilterReader
          org.apache.commons.io.input.ProxyReader

All Implemented Interfaces:

Closeable, Readable

public abstract class ProxyReader
extends FilterReader

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 FilterReader to increase reusability, because FilterReader changes the methods being called, such as read(char[]) to read(char[], int, int).

Version:

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

Field Summary

Fields inherited from class java.io.FilterReader

in

Fields inherited from class java.io.Reader

lock

Constructor Summary

ProxyReader(Reader proxy)
Constructs a new ProxyReader.

Method Summary

protected void	afterRead(int n) Invoked by the read methods after the proxied call has returned successfully.
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 idx) 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(char[] chr) Invokes the delegate's read(char[]) method.
int	read(char[] chr, int st, int len) Invokes the delegate's read(char[], int, int) method.
int	read(CharBuffer target) Invokes the delegate's read(CharBuffer) method.
boolean	ready() Invokes the delegate's ready() 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

ProxyReader

public ProxyReader(Reader proxy)

Constructs a new ProxyReader.

Parameters:

proxy - the Reader to delegate to

Method Detail

read

public int read()
         throws IOException

Invokes the delegate's read() method.

Overrides:

read in class FilterReader

Returns:

the character read or -1 if the end of stream

Throws:

IOException - if an I/O error occurs

read

public int read(char[] chr)
         throws IOException

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

Overrides:

read in class Reader

Parameters:

chr - the buffer to read the characters into

Returns:

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

Throws:

IOException - if an I/O error occurs

read

public int read(char[] chr,
                int st,
                int len)
         throws IOException

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

Overrides:

read in class FilterReader

Parameters:

chr - the buffer to read the characters into

st - The start offset

len - The number of bytes to read

Returns:

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

Throws:

IOException - if an I/O error occurs

read

public int read(CharBuffer target)
         throws IOException

Invokes the delegate's read(CharBuffer) method.

Specified by:

read in interface Readable

Overrides:

read in class Reader

Parameters:

target - the char buffer to read the characters into

Returns:

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

Throws:

IOException - if an I/O error occurs

Since:

2.0

skip

public long skip(long ln)
          throws IOException

Invokes the delegate's skip(long) method.

Overrides:

skip in class FilterReader

Parameters:

ln - the number of bytes to skip

Returns:

the number of bytes to skipped or -1 if the end of stream

Throws:

IOException - if an I/O error occurs

ready

public boolean ready()
              throws IOException

Invokes the delegate's ready() method.

Overrides:

ready in class FilterReader

Returns:

true if the stream is ready to be read

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 FilterReader

Throws:

IOException - if an I/O error occurs

mark

public void mark(int idx)
          throws IOException

Invokes the delegate's mark(int) method.

Overrides:

mark in class FilterReader

Parameters:

idx - read ahead limit

Throws:

IOException - if an I/O error occurs

reset

public void reset()
           throws IOException

Invokes the delegate's reset() method.

Overrides:

reset in class FilterReader

Throws:

IOException - if an I/O error occurs

markSupported

public boolean markSupported()

Invokes the delegate's markSupported() method.

Overrides:

markSupported in class FilterReader

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 chars that the caller wanted to read (1 for the read() method, buffer length for read(char[]), 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 chars 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 chars 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 chars 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