ProxyInputStream (Commons IO 2.5)
Date: 2016-12-01

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:
    java.io.Closeable, java.lang.AutoCloseable
  Direct Known Subclasses:
    AutoCloseInputStream, BOMInputStream, CloseShieldInputStream, CountingInputStream, SwappedDataInputStream, TaggedInputStream, TeeInputStream

      public abstract class ProxyInputStream
      extends java.io.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 1603493 2014-06-18 15:46:07Z ggregory $

- - ### Field Summary

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

      `in`

  - ### Constructor Summary

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

  - ### Method Summary

    Methods
    Modifier and Type | Method and 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(java.io.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(java.io.InputStream proxy)

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

  - ### Method Detail

    - #### read

          public int read()
                   throws java.io.IOException

      Invokes the delegate's `read()` method.
      Overrides:
        `read` in class `java.io.FilterInputStream`
      Returns:
        the byte read or -1 if the end of stream
      Throws:
        `java.io.IOException` - if an I/O error occurs

    - #### read

          public int read(byte[] bts)
                   throws java.io.IOException

      Invokes the delegate's `read(byte[])` method.
      Overrides:
        `read` in class `java.io.FilterInputStream`
      Parameters:
        `bts` - the buffer to read the bytes into
      Returns:
        the number of bytes read or EOF if the end of stream
      Throws:
        `java.io.IOException` - if an I/O error occurs

    - #### read

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

      Invokes the delegate's `read(byte[], int, int)` method.
      Overrides:
        `read` in class `java.io.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:
        `java.io.IOException` - if an I/O error occurs

    - #### skip

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

      Invokes the delegate's `skip(long)` method.
      Overrides:
        `skip` in class `java.io.FilterInputStream`
      Parameters:
        `ln` - the number of bytes to skip
      Returns:
        the actual number of bytes skipped
      Throws:
        `java.io.IOException` - if an I/O error occurs

    - #### available

          public int available()
                        throws java.io.IOException

      Invokes the delegate's `available()` method.
      Overrides:
        `available` in class `java.io.FilterInputStream`
      Returns:
        the number of available bytes
      Throws:
        `java.io.IOException` - if an I/O error occurs

    - #### close

          public void close()
                     throws java.io.IOException

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

    - #### mark

          public void mark(int readlimit)

      Invokes the delegate's `mark(int)` method.
      Overrides:
        `mark` in class `java.io.FilterInputStream`
      Parameters:
        `readlimit` - read ahead limit

    - #### reset

          public void reset()
                     throws java.io.IOException

      Invokes the delegate's `reset()` method.
      Overrides:
        `reset` in class `java.io.FilterInputStream`
      Throws:
        `java.io.IOException` - if an I/O error occurs

    - #### markSupported

          public boolean markSupported()

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

    - #### beforeRead

          protected void beforeRead(int n)
                             throws java.io.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:
        `java.io.IOException` - if the pre-processing fails
      Since:
        2.0

    - #### afterRead

          protected void afterRead(int n)
                            throws java.io.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:
        `java.io.IOException` - if the post-processing fails
      Since:
        2.0

    - #### handleIOException

          protected void handleIOException(java.io.IOException e)
                                    throws java.io.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:
        `java.io.IOException` - if an I/O error occurs
      Since:
        2.0

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