Package org.apache.wicket.util.io

Class ProxyInputStream

  • All Implemented Interfaces:
    Closeable, AutoCloseable
    Direct Known Subclasses:
    BOMInputStream
    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:
    $Id$

    • Constructor Detail

      • ProxyInputStream

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

    • Method Detail

      • 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

      • mark

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

      • 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