Class ProxyReader

java.lang.Object
java.io.Reader
java.io.FilterReader
org.apache.commons.io.input.ProxyReader
All Implemented Interfaces:
Closeable, AutoCloseable, Readable
Direct Known Subclasses:
BoundedReader, CloseShieldReader, TaggedReader, TeeReader
public abstract class ProxyReader extends FilterReader
A reader proxy which delegates to the wrapped reader.

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).

  • Constructor Details

    • ProxyReader

      public ProxyReader(Reader delegate)
      Constructs a new ProxyReader.
      Parameters:
      delegate - the Reader 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 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

    • 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

    • 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 FilterReader
      Throws:
      IOException - if an I/O error occurs.

    • handleIOException

      protected void handleIOException(IOException e) throws IOException
      Handle any IOExceptions thrown.

      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 readAheadLimit) throws IOException
      Invokes the delegate's mark(int) method.
      Overrides:
      mark in class FilterReader
      Parameters:
      readAheadLimit - read ahead limit.
      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.

    • 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

    • 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.

    • 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.

    • setReference

      public ProxyReader setReference(Reader in)
      Sets the underlying reader.

      Use with caution.

      Parameters:
      in - The input stream to set in java.io.Reader#in.
      Returns:
      this instance.
      Since:
      2.22.0

    • 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 EOF if the end of stream.
      Throws:
      IOException - if an I/O error occurs.

    • unwrap

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

      Use with caution.

      Returns:
      the underlying Reader.
      Since:
      2.22.0