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, BoundedInputStream, CloseShieldInputStream, CountingInputStream, MarkShieldInputStream, ObservableInputStream, SwappedDataInputStream, TaggedInputStream, TeeInputStream
public abstract class ProxyInputStream extends FilterInputStream
A proxy stream which acts as a FilterInputStream, by passing all method calls on to the proxied stream, not changing which methods are 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).

In addition, this class allows you to:

  • Constructor Details

    • ProxyInputStream

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

  • 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 EOF 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 EOF if the end of stream was reached.
      Throws:
      IOException - if the post-processing fails in a subclass.
      Since:
      2.0

    • available

      public int available() throws IOException
      Invokes the delegate's InputStream.available() method.
      Overrides:
      available in class FilterInputStream
      Returns:
      the number of available bytes, 0 if the stream is closed.
      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 in a subclass.
      Since:
      2.0

    • close

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

    • markSupported

      public boolean markSupported()
      Invokes the delegate's InputStream.markSupported() method.
      Overrides:
      markSupported in class FilterInputStream
      Returns:
      true if this stream instance supports the mark and reset methods; false otherwise.
      See Also:

    • read

      public int read() throws IOException
      Invokes the delegate's InputStream.read() method unless the stream is closed.
      Overrides:
      read in class FilterInputStream
      Returns:
      the byte read or EOF if we reached the end of stream.
      Throws:
      IOException - if an I/O error occurs.

    • read

      public int read(byte[] b) throws IOException
      Invokes the delegate's InputStream.read(byte[]) method.
      Overrides:
      read in class FilterInputStream
      Parameters:
      b - the buffer to read the bytes into.
      Returns:
      the number of bytes read or EOF if we reached the end of stream.
      Throws:
      IOException -
      • If the first byte cannot be read for any reason other than the end of the file,
      • if the input stream has been closed, or
      • if some other I/O error occurs.

    • read

      public int read(byte[] b, int off, int len) throws IOException
      Invokes the delegate's InputStream.read(byte[], int, int) method.
      Overrides:
      read in class FilterInputStream
      Parameters:
      b - 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 EOF if we reached the end of stream.
      Throws:
      IOException -
      • If the first byte cannot be read for any reason other than the end of the file,
      • if the input stream has been closed, or
      • if some other I/O error occurs.

    • reset

      public void reset() throws IOException
      Invokes the delegate's InputStream.reset() method.
      Overrides:
      reset in class FilterInputStream
      Throws:
      IOException - if this stream has not been marked or if the mark has been invalidated.

    • skip

      public long skip(long n) throws IOException
      Invokes the delegate's InputStream.skip(long) method.
      Overrides:
      skip in class FilterInputStream
      Parameters:
      n - the number of bytes to skip.
      Returns:
      the actual number of bytes skipped.
      Throws:
      IOException - if the stream does not support seek, or if some other I/O error occurs.

    • unwrap

      public InputStream unwrap()
      Unwraps this instance by returning the underlying InputStream.

      Use with caution; useful to query the underlying InputStream.

      Returns:
      the underlying InputStream.
      Since:
      2.16.0