Package 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`, `AutoCloseable`

Direct Known Subclasses:
  `AutoCloseInputStream`, `BOMInputStream`, `CloseShieldInputStream`, `CountingInputStream`, `MarkShieldInputStream`, `ObservableInputStream`, `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.

- ## Field Summary

  ### Fields inherited from class java.io.FilterInputStream

  `in`

- ## Constructor Summary

  Constructors
  Constructor
  Description
  `ProxyInputStream(InputStream proxy)`
  Constructs a new ProxyInputStream.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `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; by default, throws the given exception.
  `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 Details

  - ### ProxyInputStream

    public ProxyInputStream(InputStream proxy)
    Constructs a new ProxyInputStream.
    Parameters:
      `proxy` - the InputStream to delegate to

- ## Method Details

  - ### 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

  - ### 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.

  - ### 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

  - ### close

    public void close() throws IOException
    Invokes the delegate's `close()` method.
    Specified by:
      `close` in interface `AutoCloseable`
    Specified by:
      `close` in interface `Closeable`
    Overrides:
      `close` in class `FilterInputStream`
    Throws:
      `IOException` - if an I/O error occurs.

  - ### handleIOException

    protected void handleIOException(IOException e) throws IOException
    Handle any IOExceptions thrown; by default, throws the given exception.

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

    Parameters:
      `e` - The IOException thrown
    Throws:
      `IOException` - if an I/O error occurs.
    Since:
      2.0

  - ### mark

    public void mark(int readLimit)
    Invokes the delegate's `mark(int)` method.
    Overrides:
      `mark` in class `FilterInputStream`
    Parameters:
      `readLimit` - read ahead limit

  - ### markSupported

    public boolean markSupported()
    Invokes the delegate's `markSupported()` method.
    Overrides:
      `markSupported` in class `FilterInputStream`
    Returns:
      true if mark is supported, otherwise false

  - ### 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 EOF 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.

  - ### 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.

  - ### 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.