/*
* Copyright 1996-2005 Sun Microsystems, Inc. All Rights Reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code 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. Sun designates this
* particular file as subject to the "Classpath" exception as provided
* by Sun in the LICENSE file that accompanied this code.
*
* This code 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 in the LICENSE file that
* accompanied this code).
*
* 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 USA or visit www.sun.com if you need additional information or
* have any questions.
*/
package java.io;
import java.nio.charset.Charset;
import java.nio.charset.CharsetDecoder;
import sun.nio.cs.StreamDecoder;
/**
* An InputStreamReader is a bridge from byte streams to character streams: It
* reads bytes and decodes them into characters using a specified {@link
* java.nio.charset.Charset <code>charset</code>}. The charset that it uses
* may be specified by name or may be given explicitly, or the platform's
* default charset 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.
*
* <p> For top efficiency, consider wrapping an InputStreamReader within a
* BufferedReader. For example:
*
* <pre>
* BufferedReader in
* = new BufferedReader(new InputStreamReader(System.in));
* </pre>
*
* @see BufferedReader
* @see InputStream
* @see java.nio.charset.Charset
*
* @version 1.53, 07/05/05
* @author Mark Reinhold
* @since JDK1.1
*/
public class InputStreamReader extends Reader {
private final StreamDecoder sd;
/**
* Creates an InputStreamReader that uses the default charset.
*
* @param in An InputStream
*/
public InputStreamReader(InputStream in) {
super (in);
try {
sd = StreamDecoder.forInputStreamReader(in, this ,
(String) null); // ## check lock object
} catch (UnsupportedEncodingException e) {
// The default encoding should always be available
throw new Error(e);
}
}
/**
* Creates an InputStreamReader that uses the named charset.
*
* @param in
* An InputStream
*
* @param charsetName
* The name of a supported
* {@link java.nio.charset.Charset </code>charset<code>}
*
* @exception UnsupportedEncodingException
* If the named charset is not supported
*/
public InputStreamReader(InputStream in, String charsetName)
throws UnsupportedEncodingException {
super (in);
if (charsetName == null)
throw new NullPointerException("charsetName");
sd = StreamDecoder.forInputStreamReader(in, this , charsetName);
}
/**
* Creates an InputStreamReader that uses the given charset. </p>
*
* @param in An InputStream
* @param cs A charset
*
* @since 1.4
* @spec JSR-51
*/
public InputStreamReader(InputStream in, Charset cs) {
super (in);
if (cs == null)
throw new NullPointerException("charset");
sd = StreamDecoder.forInputStreamReader(in, this , cs);
}
/**
* Creates an InputStreamReader that uses the given charset decoder. </p>
*
* @param in An InputStream
* @param dec A charset decoder
*
* @since 1.4
* @spec JSR-51
*/
public InputStreamReader(InputStream in, CharsetDecoder dec) {
super (in);
if (dec == null)
throw new NullPointerException("charset decoder");
sd = StreamDecoder.forInputStreamReader(in, this , dec);
}
/**
* Returns the name of the character encoding being used by this stream.
*
* <p> If the encoding has an historical name then that name is returned;
* otherwise the encoding's canonical name is returned.
*
* <p> If this instance was created with the {@link
* #InputStreamReader(InputStream, String)} constructor then the returned
* name, being unique for the encoding, may differ from the name passed to
* the constructor. This method will return <code>null</code> if the
* stream has been closed.
* </p>
* @return The historical name of this encoding, or
* <code>null</code> if the stream has been closed
*
* @see java.nio.charset.Charset
*
* @revised 1.4
* @spec JSR-51
*/
public String getEncoding() {
return sd.getEncoding();
}
/**
* Reads 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 {
return sd.read();
}
/**
* Reads characters into a portion of an array.
*
* @param cbuf Destination buffer
* @param offset Offset at which to start storing characters
* @param length 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 offset, int length)
throws IOException {
return sd.read(cbuf, offset, length);
}
/**
* Tells whether this stream is ready to be read. An InputStreamReader is
* ready if its input buffer is not empty, or if bytes are available to be
* read from the underlying byte stream.
*
* @exception IOException If an I/O error occurs
*/
public boolean ready() throws IOException {
return sd.ready();
}
public void close() throws IOException {
sd.close();
}
}
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