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package com.sun.org.apache.xerces.internal.impl.io;

import java.io.IOException;
import java.io.InputStream;
import java.io.Reader;
import java.util.Locale;

import com.sun.org.apache.xerces.internal.impl.msg.XMLMessageFormatter;
import com.sun.org.apache.xerces.internal.util.MessageFormatter;



A UTF-16 reader. Can also be used for UCS-2 (i.e. ISO-10646-UCS-2).


Author:Michael Glavassevich, IBM
@xerces.internal
Version:$Id: UTF16Reader.java 718095 2008-11-16 20:00:14Z mrglavas $
/**
 * <p>
 * A UTF-16 reader. Can also be used for UCS-2 (i.e. ISO-10646-UCS-2).</p>
 *
 * @xerces.internal
 *
 * @author Michael Glavassevich, IBM
 *
 * @version $Id: UTF16Reader.java 718095 2008-11-16 20:00:14Z mrglavas $
 */
public final class UTF16Reader
        extends Reader {

    //
    // Constants
    //
    
Default byte buffer size (4096).

/**
     * Default byte buffer size (4096).
     */
    public static final int DEFAULT_BUFFER_SIZE = 4096;

    //
    // Data
    //
    
Input stream.

/**
     * Input stream.
     */
    protected final InputStream fInputStream;

    
Byte buffer.

/**
     * Byte buffer.
     */
    protected final byte[] fBuffer;

    
Endianness.

/**
     * Endianness.
     */
    protected final boolean fIsBigEndian;

    // message formatter; used to produce localized exception messages
    private final MessageFormatter fFormatter;

    // Locale to use for messages
    private final Locale fLocale;

    //
    // Constructors
    //
    
Constructs a UTF-16 reader from the specified input stream using the
default buffer size. Primarily for testing.

Params:
  • inputStream – The input stream.
  • isBigEndian – The byte order.
/**
     * Constructs a UTF-16 reader from the specified input stream using the
     * default buffer size. Primarily for testing.
     *
     * @param inputStream The input stream.
     * @param isBigEndian The byte order.
     */
    public UTF16Reader(InputStream inputStream, boolean isBigEndian) {
        this(inputStream, DEFAULT_BUFFER_SIZE, isBigEndian,
                new XMLMessageFormatter(), Locale.getDefault());
    } // <init>(InputStream, boolean)

    
Constructs a UTF-16 reader from the specified input stream using the
default buffer size and the given MessageFormatter.

Params:
  • inputStream – The input stream.
  • isBigEndian – The byte order.
/**
     * Constructs a UTF-16 reader from the specified input stream using the
     * default buffer size and the given MessageFormatter.
     *
     * @param inputStream The input stream.
     * @param isBigEndian The byte order.
     */
    public UTF16Reader(InputStream inputStream, boolean isBigEndian,
            MessageFormatter messageFormatter, Locale locale) {
        this(inputStream, DEFAULT_BUFFER_SIZE, isBigEndian, messageFormatter, locale);
    } // <init>(InputStream, boolean, MessageFormatter, Locale)

    
Constructs a UTF-16 reader from the specified input stream and buffer
size and given MessageFormatter.

Params:
  • inputStream – The input stream.
  • size – The initial buffer size.
  • isBigEndian – The byte order.
  • messageFormatter – Given MessageFormatter
  • locale – Locale to use for messages
/**
     * Constructs a UTF-16 reader from the specified input stream and buffer
     * size and given MessageFormatter.
     *
     * @param inputStream The input stream.
     * @param size The initial buffer size.
     * @param isBigEndian The byte order.
     * @param messageFormatter Given MessageFormatter
     * @param locale Locale to use for messages
     */
    public UTF16Reader(InputStream inputStream, int size, boolean isBigEndian,
            MessageFormatter messageFormatter, Locale locale) {
        this(inputStream, new byte[size], isBigEndian, messageFormatter, locale);
    } // <init>(InputStream, int, boolean, MessageFormatter, Locale)

    
Constructs a UTF-16 reader from the specified input stream, buffer and
MessageFormatter.

Params:
  • inputStream – The input stream.
  • buffer – The byte buffer.
  • isBigEndian – The byte order.
  • messageFormatter – Given MessageFormatter
  • locale – Locale to use for messages
/**
     * Constructs a UTF-16 reader from the specified input stream, buffer and
     * MessageFormatter.
     *
     * @param inputStream The input stream.
     * @param buffer The byte buffer.
     * @param isBigEndian The byte order.
     * @param messageFormatter Given MessageFormatter
     * @param locale Locale to use for messages
     */
    public UTF16Reader(InputStream inputStream, byte[] buffer, boolean isBigEndian,
            MessageFormatter messageFormatter, Locale locale) {
        fInputStream = inputStream;
        fBuffer = buffer;
        fIsBigEndian = isBigEndian;
        fFormatter = messageFormatter;
        fLocale = locale;
    } // <init>(InputStream, byte[], boolean, MessageFormatter, Locale)

    //
    // Reader methods
    //
    
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.


Subclasses that intend to support efficient single-character input should
override this method.

Throws:
Returns:The character read, as an integer in the range 0 to 65535
(0x00-0xffff), or -1 if the end of the stream has been reached
/**
     * 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.
     *
     * <p>
     * Subclasses that intend to support efficient single-character input should
     * override this method.
     *
     * @return The character read, as an integer in the range 0 to 65535
     * (<tt>0x00-0xffff</tt>), or -1 if the end of the stream has been reached
     *
     * @exception IOException If an I/O error occurs
     */
    public int read() throws IOException {
        final int b0 = fInputStream.read();
        if (b0 == -1) {
            return -1;
        }
        final int b1 = fInputStream.read();
        if (b1 == -1) {
            expectedTwoBytes();
        }
        // UTF-16BE
        if (fIsBigEndian) {
            return (b0 << 8) | b1;
        }
        // UTF-16LE
        return (b1 << 8) | b0;
    } // read():int

    
Read characters into a portion of an array. This method will block until
some input is available, an I/O error occurs, or the end of the stream is
reached.

Params:
  • ch – Destination buffer
  • offset – Offset at which to start storing characters
  • length – Maximum number of characters to read
Throws:
Returns:The number of characters read, or -1 if the end of the stream has
been reached
/**
     * Read characters into a portion of 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 ch 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 ch[], int offset, int length) throws IOException {
        int byteLength = length << 1;
        if (byteLength > fBuffer.length) {
            byteLength = fBuffer.length;
        }
        int byteCount = fInputStream.read(fBuffer, 0, byteLength);
        if (byteCount == -1) {
            return -1;
        }
        // If an odd number of bytes were read, we still need to read one more.
        if ((byteCount & 1) != 0) {
            int b = fInputStream.read();
            if (b == -1) {
                expectedTwoBytes();
            }
            fBuffer[byteCount++] = (byte) b;
        }
        final int charCount = byteCount >> 1;
        if (fIsBigEndian) {
            processBE(ch, offset, charCount);
        } else {
            processLE(ch, offset, charCount);
        }
        return charCount;
    } // read(char[],int,int)

    
Skip characters. This method will block until some characters are
available, an I/O error occurs, or the end of the stream is reached.

Params:
  • n – The number of characters to skip
Throws:
Returns:The number of characters actually skipped
/**
     * 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
     *
     * @exception IOException If an I/O error occurs
     */
    public long skip(long n) throws IOException {
        long bytesSkipped = fInputStream.skip(n << 1);
        if ((bytesSkipped & 1) != 0) {
            int b = fInputStream.read();
            if (b == -1) {
                expectedTwoBytes();
            }
            ++bytesSkipped;
        }
        return bytesSkipped >> 1;
    } // skip(long):long

    
Tell whether this stream is ready to be read.

Throws:
Returns: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.
/**
     * 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 {
        return false;
    } // ready()

    
Tell whether this stream supports the mark() operation.

/**
     * Tell whether this stream supports the mark() operation.
     */
    public boolean markSupported() {
        return false;
    } // markSupported()

    
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.

Params:
  • 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
/**
     * 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.
     *
     * @exception IOException If the stream does not support mark(), or if some
     * other I/O error occurs
     */
    public void mark(int readAheadLimit) throws IOException {
        throw new IOException(fFormatter.formatMessage(fLocale, "OperationNotSupported", new Object[]{"mark()", "UTF-16"}));
    } // mark(int)

    
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
/**
     * 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().
     *
     * @exception 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
     */
    public void reset() throws IOException {
    } // reset()

    
Close the stream. Once a stream has been closed, further read(), ready(),
mark(), or reset() invocations will throw an IOException. Closing a
previously-closed stream, however, has no effect.

Throws:
  • IOException – If an I/O error occurs
/**
     * Close the stream. Once a stream has been closed, further read(), ready(),
     * mark(), or reset() invocations will throw an IOException. Closing a
     * previously-closed stream, however, has no effect.
     *
     * @exception IOException If an I/O error occurs
     */
    public void close() throws IOException {
        fInputStream.close();
    } // close()

    //
    // Private methods
    //
    
Decodes UTF-16BE *

/**
     * Decodes UTF-16BE *
     */
    private void processBE(final char ch[], int offset, final int count) {
        int curPos = 0;
        for (int i = 0; i < count; ++i) {
            final int b0 = fBuffer[curPos++] & 0xff;
            final int b1 = fBuffer[curPos++] & 0xff;
            ch[offset++] = (char) ((b0 << 8) | b1);
        }
    } // processBE(char[],int,int)

    
Decodes UTF-16LE *

/**
     * Decodes UTF-16LE *
     */
    private void processLE(final char ch[], int offset, final int count) {
        int curPos = 0;
        for (int i = 0; i < count; ++i) {
            final int b0 = fBuffer[curPos++] & 0xff;
            final int b1 = fBuffer[curPos++] & 0xff;
            ch[offset++] = (char) ((b1 << 8) | b0);
        }
    } // processLE(char[],int,int)

    
Throws an exception for expected byte.

/**
     * Throws an exception for expected byte.
     */
    private void expectedTwoBytes()
            throws MalformedByteSequenceException {
        throw new MalformedByteSequenceException(fFormatter,
                fLocale,
                XMLMessageFormatter.XML_DOMAIN,
                "ExpectedByte",
                new Object[]{"2", "2"});
    } // expectedTwoBytes()

} // class UTF16Reader