| /* InputStreamReader.java -- Reader than transforms bytes to chars |
| Copyright (C) 1998, 1999, 2001, 2003, 2004, 2005 Free Software Foundation, Inc. |
| |
| This file is part of GNU Classpath. |
| |
| GNU Classpath 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, or (at your option) |
| any later version. |
| |
| GNU Classpath 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. |
| |
| You should have received a copy of the GNU General Public License |
| along with GNU Classpath; see the file COPYING. If not, write to the |
| Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
| 02110-1301 USA. |
| |
| Linking this library statically or dynamically with other modules is |
| making a combined work based on this library. Thus, the terms and |
| conditions of the GNU General Public License cover the whole |
| combination. |
| |
| As a special exception, the copyright holders of this library give you |
| permission to link this library with independent modules to produce an |
| executable, regardless of the license terms of these independent |
| modules, and to copy and distribute the resulting executable under |
| terms of your choice, provided that you also meet, for each linked |
| independent module, the terms and conditions of the license of that |
| module. An independent module is a module which is not derived from |
| or based on this library. If you modify this library, you may extend |
| this exception to your version of the library, but you are not |
| obligated to do so. If you do not wish to do so, delete this |
| exception statement from your version. */ |
| |
| |
| package java.io; |
| |
| import gnu.gcj.convert.*; |
| import java.nio.charset.Charset; |
| import java.nio.charset.CharsetDecoder; |
| |
| /** |
| * This class reads characters from a byte input stream. The characters |
| * read are converted from bytes in the underlying stream by a |
| * decoding layer. The decoding layer transforms bytes to chars according |
| * to an encoding standard. There are many available encodings to choose |
| * from. The desired encoding can either be specified by name, or if no |
| * encoding is selected, the system default encoding will be used. The |
| * system default encoding name is determined from the system property |
| * <code>file.encoding</code>. The only encodings that are guaranteed to |
| * be availalbe are "8859_1" (the Latin-1 character set) and "UTF8". |
| * Unforunately, Java does not provide a mechanism for listing the |
| * ecodings that are supported in a given implementation. |
| * <p> |
| * Here is a list of standard encoding names that may be available: |
| * <p> |
| * <ul> |
| * <li>8859_1 (ISO-8859-1/Latin-1)</li> |
| * <li>8859_2 (ISO-8859-2/Latin-2)</li> |
| * <li>8859_3 (ISO-8859-3/Latin-3)</li> |
| * <li>8859_4 (ISO-8859-4/Latin-4)</li> |
| * <li>8859_5 (ISO-8859-5/Latin-5)</li> |
| * <li>8859_6 (ISO-8859-6/Latin-6)</li> |
| * <li>8859_7 (ISO-8859-7/Latin-7)</li> |
| * <li>8859_8 (ISO-8859-8/Latin-8)</li> |
| * <li>8859_9 (ISO-8859-9/Latin-9)</li> |
| * <li>ASCII (7-bit ASCII)</li> |
| * <li>UTF8 (UCS Transformation Format-8)</li> |
| * <li>More later</li> |
| * </ul> |
| * <p> |
| * It is recommended that applications do not use |
| * <code>InputStreamReader</code>'s |
| * directly. Rather, for efficiency purposes, an object of this class |
| * should be wrapped by a <code>BufferedReader</code>. |
| * <p> |
| * Due to a deficiency the Java class library design, there is no standard |
| * way for an application to install its own byte-character encoding. |
| * |
| * @see BufferedReader |
| * @see InputStream |
| * |
| * @author Aaron M. Renn (arenn@urbanophile.com) |
| * @author Per Bothner (bothner@cygnus.com) |
| * @date April 22, 1998. |
| */ |
| public class InputStreamReader extends Reader |
| { |
| BufferedInputStream in; |
| |
| // Buffer of chars read from in and converted but not consumed. |
| char[] work; |
| // Next available character (in work buffer) to read. |
| int wpos; |
| // Last available character (in work buffer) to read. |
| int wcount; |
| |
| /* |
| * This is the byte-character decoder class that does the reading and |
| * translation of bytes from the underlying stream. |
| */ |
| BytesToUnicode converter; |
| |
| /** |
| * This method initializes a new instance of <code>InputStreamReader</code> |
| * to read from the specified stream using the default encoding. |
| * |
| * @param in The <code>InputStream</code> to read from |
| */ |
| public InputStreamReader(InputStream in) |
| { |
| this(in, BytesToUnicode.getDefaultDecoder()); |
| } |
| |
| /** |
| * This method initializes a new instance of <code>InputStreamReader</code> |
| * to read from the specified stream using a caller supplied character |
| * encoding scheme. Note that due to a deficiency in the Java language |
| * design, there is no way to determine which encodings are supported. |
| * |
| * @param in The <code>InputStream</code> to read from |
| * @param encoding_name The name of the encoding scheme to use |
| * |
| * @exception UnsupportedEncodingException If the encoding scheme |
| * requested is not available. |
| */ |
| public InputStreamReader(InputStream in, String encoding_name) |
| throws UnsupportedEncodingException |
| { |
| this(in, BytesToUnicode.getDecoder(encoding_name)); |
| } |
| |
| /** |
| * Creates an InputStreamReader that uses a decoder of the given |
| * charset to decode the bytes in the InputStream into |
| * characters. |
| */ |
| public InputStreamReader(InputStream in, Charset charset) |
| { |
| this(in, new BytesToCharsetAdaptor(charset)); |
| } |
| |
| /** |
| * Creates an InputStreamReader that uses the given charset decoder |
| * to decode the bytes in the InputStream into characters. |
| */ |
| public InputStreamReader(InputStream in, CharsetDecoder decoder) |
| { |
| this(in, new BytesToCharsetAdaptor(decoder)); |
| } |
| |
| private InputStreamReader(InputStream in, BytesToUnicode decoder) |
| { |
| // FIXME: someone could pass in a BufferedInputStream whose buffer |
| // is smaller than the longest encoded character for this |
| // encoding. We will probably go into an infinite loop in this |
| // case. We probably ought to just have our own byte buffering |
| // here. |
| this.in = in instanceof BufferedInputStream |
| ? (BufferedInputStream) in |
| : new BufferedInputStream(in); |
| /* Don't need to call super(in) here as long as the lock gets set. */ |
| this.lock = in; |
| converter = decoder; |
| converter.setInput(this.in.buf, 0, 0); |
| } |
| |
| /** |
| * This method closes this stream, as well as the underlying |
| * <code>InputStream</code>. |
| * |
| * @exception IOException If an error occurs |
| */ |
| public void close() throws IOException |
| { |
| synchronized (lock) |
| { |
| if (in != null) |
| in.close(); |
| in = null; |
| work = null; |
| wpos = wcount = 0; |
| } |
| } |
| |
| /** |
| * This method returns the name of the encoding that is currently in use |
| * by this object. If the stream has been closed, this method is allowed |
| * to return <code>null</code>. |
| * |
| * @return The current encoding name |
| */ |
| public String getEncoding() |
| { |
| return in != null ? converter.getName() : null; |
| } |
| |
| /** |
| * This method checks to see if the stream is read to be read. It |
| * will return <code>true</code> if is, or <code>false</code> if it is not. |
| * If the stream is not ready to be read, it could (although is not required |
| * to) block on the next read attempt. |
| * |
| * @return <code>true</code> if the stream is ready to be read, |
| * <code>false</code> otherwise |
| * |
| * @exception IOException If an error occurs |
| */ |
| public boolean ready() throws IOException |
| { |
| synchronized (lock) |
| { |
| if (in == null) |
| throw new IOException("Stream closed"); |
| |
| if (wpos < wcount) |
| return true; |
| |
| // According to the spec, an InputStreamReader is ready if its |
| // input buffer is not empty (above), or if bytes are |
| // available on the underlying byte stream. |
| return in.available () > 0; |
| } |
| } |
| |
| /** |
| * This method reads up to <code>length</code> characters from the stream into |
| * the specified array starting at index <code>offset</code> into the |
| * array. |
| * |
| * @param buf The character array to recieve the data read |
| * @param offset The offset into the array to start storing characters |
| * @param length The requested number of characters to read. |
| * |
| * @return The actual number of characters read, or -1 if end of stream. |
| * |
| * @exception IOException If an error occurs |
| */ |
| public int read (char[] buf, int offset, int length) throws IOException |
| { |
| synchronized (lock) |
| { |
| if (in == null) |
| throw new IOException("Stream closed"); |
| |
| if (length == 0) |
| return 0; |
| |
| int wavail = wcount - wpos; |
| if (wavail <= 0) |
| { |
| // Nothing waiting, so refill their buffer. |
| return refill(buf, offset, length); |
| } |
| |
| if (length > wavail) |
| length = wavail; |
| System.arraycopy(work, wpos, buf, offset, length); |
| wpos += length; |
| return length; |
| } |
| } |
| |
| /** |
| * This method reads a single character of data from the stream. |
| * |
| * @return The char read, as an int, or -1 if end of stream. |
| * |
| * @exception IOException If an error occurs |
| */ |
| public int read() throws IOException |
| { |
| synchronized (lock) |
| { |
| if (in == null) |
| throw new IOException("Stream closed"); |
| |
| int wavail = wcount - wpos; |
| if (wavail <= 0) |
| { |
| // Nothing waiting, so refill our internal buffer. |
| wpos = wcount = 0; |
| if (work == null) |
| work = new char[100]; |
| int count = refill(work, 0, work.length); |
| if (count == -1) |
| return -1; |
| wcount += count; |
| } |
| |
| return work[wpos++]; |
| } |
| } |
| |
| // Read more bytes and convert them into the specified buffer. |
| // Returns the number of converted characters or -1 on EOF. |
| private int refill(char[] buf, int offset, int length) throws IOException |
| { |
| for (;;) |
| { |
| // We have knowledge of the internals of BufferedInputStream |
| // here. Eww. |
| // BufferedInputStream.refill() can only be called when |
| // `pos>=count'. |
| boolean r = in.pos < in.count || in.refill (); |
| if (! r) |
| return -1; |
| converter.setInput(in.buf, in.pos, in.count); |
| int count = converter.read(buf, offset, length); |
| |
| // We might have bytes but not have made any progress. In |
| // this case we try to refill. If refilling fails, we assume |
| // we have a malformed character at the end of the stream. |
| if (count == 0 && converter.inpos == in.pos) |
| { |
| in.mark(in.count); |
| if (! in.refill ()) |
| throw new CharConversionException (); |
| in.reset(); |
| } |
| else |
| { |
| in.skip(converter.inpos - in.pos); |
| if (count > 0) |
| return count; |
| } |
| } |
| } |
| } |