/*
*
*
* Copyright 1990-2009 Sun Microsystems, Inc. All Rights Reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License version
* 2 only, as published by the Free Software Foundation.
*
* 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 version 2 for more details (a copy is
* included at /legal/license.txt).
*
* You should have received a copy of the GNU General Public License
* version 2 along with this work; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA
*
* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa
* Clara, CA 95054 or visit www.sun.com if you need additional
* information or have any questions.
*/
package java.io;
import com.sun.cldc.i18n.*;
/**
* An InputStreamReader is a bridge from byte streams to character streams:
* It reads bytes and translates them into characters.
* The encoding that it uses may be specified by name, or the platform's
* default encoding may be accepted.
*
* <p> Each invocation of one of an InputStreamReader's read() methods may
* cause one or more bytes to be read from the underlying byte input stream.
* To enable the efficient conversion of bytes to characters, more bytes may
* be read ahead from the underlying stream than are necessary to satisfy the
* current read operation.
*
* @version 12/17/01 (CLDC 1.1)
* @see java.io.Reader
* @see java.io.UnsupportedEncodingException
* @since CLDC 1.0
*/
public class InputStreamReader extends Reader {
/**
* The underlying character input stream.
*/
private Reader in;
/**
* Create an InputStreamReader that uses the default character encoding.
*
* @param is An InputStream
*/
public InputStreamReader(InputStream is) {
in = Helper.getStreamReader(is);
}
/**
* Create an InputStreamReader that uses the named character encoding.
*
* @param is An InputStream
* @param enc The name of a supported character encoding
*
* @exception UnsupportedEncodingException
* If the named encoding is not supported
*/
public InputStreamReader(InputStream is, String enc)
throws UnsupportedEncodingException
{
in = Helper.getStreamReader(is, enc);
}
/**
* Check to make sure that the stream has not been closed
*/
private void ensureOpen() throws IOException {
if (in == null) {
throw new IOException(
/* #ifdef VERBOSE_EXCEPTIONS */
/// skipped "Stream closed"
/* #endif */
);
}
}
/**
* Read a single character.
*
* @return The character read, or -1 if the end of the stream has
* been reached
*
* @exception IOException If an I/O error occurs
*/
public int read() throws IOException {
ensureOpen();
return in.read();
}
/**
* Read characters into a portion of an array.
*
* @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 characters read, or -1 if the end of
* the stream has been reached
*
* @exception IOException If an I/O error occurs
*/
public int read(char cbuf[], int off, int len) throws IOException {
ensureOpen();
if ((off < 0) || (off > cbuf.length) || (len < 0) ||
((off + len) > cbuf.length) || ((off + len) < 0)) {
throw new IndexOutOfBoundsException();
} else if (len == 0) {
return 0;
}
return in.read(cbuf, off, len);
}
/**
* Skip characters.
*
* @param n The number of characters to skip
*
* @return The number of characters actually skipped
*
* @exception IllegalArgumentException If <code>n</code> is negative.
* @exception IOException If an I/O error occurs
*/
public long skip(long n) throws IOException {
ensureOpen();
return in.skip(n);
}
/**
* 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.
*
* @exception IOException If an I/O error occurs
*/
public boolean ready() throws IOException {
ensureOpen();
return in.ready();
}
/**
* Tell whether this stream supports the mark() operation.
*
* @return true if and only if this stream supports the mark operation.
*/
public boolean markSupported() {
if (in == null) {
return false;
}
return in.markSupported();
}
/**
* Mark the present position in the stream.
*
* @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.
*
* @exception IOException If the stream does not support mark(),
* or if some other I/O error occurs
*/
public void mark(int readAheadLimit) throws IOException {
ensureOpen();
if (in.markSupported()) {
in.mark(readAheadLimit);
} else {
throw new IOException(
/* #ifdef VERBOSE_EXCEPTIONS */
/// skipped "mark() not supported"
/* #endif */
);
}
}
/**
* Reset the stream.
*
* @exception IOException If an I/O error occurs
*/
public void reset() throws IOException {
ensureOpen();
in.reset();
}
/**
* Close the stream. Closing a previously closed stream
* has no effect.
*
* @exception IOException If an I/O error occurs
*/
public void close() throws IOException {
if (in != null) {
in.close();
in = null;
}
}
}