Mega Code Archive
A StraightStreamReader is a bridge from byte streams to character streams
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/*
* An InputStreamReader that does no character encoding translations.
* Copyright (C) 2001 Stephen Ostermiller
* http://ostermiller.org/contact.pl?regarding=Java+Utilities
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* See COPYING.TXT for details.
*/
import java.io.*;
/**
* A StraightStreamReader is a bridge from byte streams to character streams: It reads bytes
* and translates them into characters without using a character encoding. The characters
* that a StraightStreamReader returns may not be valid Unicode characters but they are
* guaranteed to be in the 0x00 to 0xFF range.
* More information about this class is available from <a target="_top" href=
* "http://ostermiller.org/utils/StraightStreamReader.html">ostermiller.org</a>.
* <P>
* Most of the time you want to do character encoding translation when translating bytes to
* characters. If you are planning on displaying the text, you should always do this and should
* use an InputStreamReader for the purpose. Sometimes it is useful to treat characters as bytes
* with some extra bits. In these cases you would want to use a StraightStreamReader.
* <P>
* For top efficiency, consider wrapping an StraightStreamReader within a BufferedReader. For example:<br>
* <code>BufferedReader in = new BufferedReader(new StraightStreamReader(System.in));</code>
*
* @author Stephen Ostermiller http://ostermiller.org/contact.pl?regarding=Java+Utilities
* @since ostermillerutils 1.00.00
*/
public class StraightStreamReader extends Reader{
/**
* The input stream from which all methods in this class read.
*
* @since ostermillerutils 1.00.00
*/
private InputStream in;
/**
* A byte array to be used for calls to the InputStream. This
* is cached as a class variable to avoid object creation and
* deletion each time a read is called. This buffer may be
* null and may not be large enough. Make sure to check i
* before using it.
*
* @since ostermillerutils 1.00.00
*/
private byte[] buffer;
/**
* Create a StraightStreamReader from an InputStream
*
* @param in InputStream to wrap a Reader around.
*
* @since ostermillerutils 1.00.00
*/
public StraightStreamReader(InputStream in) {
this.in = in;
}
/**
* Close the stream.
*
* @throws IOException If an I/O error occurs
*
* @since ostermillerutils 1.00.00
*/
@Override public void close() throws IOException {
in.close();
}
/**
* Mark the present position in the stream. Subsequent calls to reset()
* will attempt to reposition the stream to this point. Not all
* character-input streams support the mark() operation.
*
* @param readAheadLimit Limit on the number of characters that may be read
* while still preserving the mark. After reading this many characters,
* attempting to reset the stream may fail.
* @throws IOException If the stream does not support mark(), or if some other I/O error occurs
*
* @since ostermillerutils 1.00.00
*/
@Override public void mark(int readAheadLimit) throws IOException {
in.mark(readAheadLimit);
}
/**
* Tell whether this stream supports the mark() operation.
*
* @return true if and only if this stream supports the mark operation.
*
* @since ostermillerutils 1.00.00
*/
@Override public boolean markSupported(){
return in.markSupported();
}
/**
* Read a single character. This method will block until a character is available, an
* I/O error occurs, or the end of the stream is reached.
*
* @return The character read, as an integer in the range 0 to 256 (0x00-0xff), or -1 if
* the end of the stream has been reached
* @throws IOException If an I/O error occurs
*
* @since ostermillerutils 1.00.00
*/
@Override public int read() throws IOException {
return in.read();
}
/**
* Read characters into an array. This method will block until some input is available,
* an I/O error occurs, or the end of the stream is reached.
*
* @param cbuf Destination buffer
* @return The number of bytes read, or -1 if the end of the stream has been reached
* @throws IOException If an I/O error occurs
*
* @since ostermillerutils 1.00.00
*/
@Override public int read(char[] cbuf) throws IOException {
return read(cbuf, 0, cbuf.length);
}
/**
* Read characters into an array. This method will block until some input is available,
* an I/O error occurs, or the end of the stream is reached.
*
* @param cbuf Destination buffer
* @param off Offset at which to start storing characters
* @param len Maximum number of characters to read
* @return The number of bytes read, or -1 if the end of the stream has been reached
* @throws IOException If an I/O error occurs
*
* @since ostermillerutils 1.00.00
*/
@Override public int read(char[] cbuf, int off, int len) throws IOException {
// ensure the capacity of the buffer that we will be using
// to read from the input stream
if (buffer == null || buffer.length < len){
buffer = new byte[len];
}
// read from the input stream and copy it to the character array
int length = in.read(buffer, 0, len);
for (int i=0; i<length; i++){
cbuf[off+i] = (char)(0xFF & buffer[i]);
}
return length;
}
/**
* Tell whether this stream is ready to be read.
*
* @return True if the next read() is guaranteed not to block for input, false otherwise.
* Note that returning false does not guarantee that the next read will block.
* @throws IOException If an I/O error occurs
*
* @since ostermillerutils 1.00.00
*/
@Override public boolean ready() throws IOException {
return (in.available() > 0);
}
/**
* Reset the stream. If the stream has been marked, then attempt to reposition it at the mark.
* If the stream has not been marked, then attempt to reset it in some way appropriate to the
* particular stream, for example by repositioning it to its starting point. Not all
* character-input streams support the reset() operation, and some support reset()
* without supporting mark().
*
* @throws IOException If the stream has not been marked, or if the mark has been invalidated,
* or if the stream does not support reset(), or if some other I/O error occurs
*
* @since ostermillerutils 1.00.00
*/
@Override public void reset() throws IOException {
in.reset();
}
/**
* Skip characters. This method will block until some characters are available,
* an I/O error occurs, or the end of the stream is reached.
*
* @param n The number of characters to skip
* @return The number of characters actually skipped
* @throws IllegalArgumentException If n is negative
* @throws IOException If an I/O error occurs
*
* @since ostermillerutils 1.00.00
*/
@Override public long skip(long n) throws IOException {
return in.skip(n);
}
}
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