File	Doc	Category	Size	Date	Package
UCSReader.java	API Doc	Java SE 5 API	12978	Fri Aug 26 14:55:48 BST 2005	com.sun.org.apache.xerces.internal.impl.io

UCSReader

• java.lang.Object
  • java.io.Reader

Fields Summary
public static final int	DEFAULT_BUFFER_SIZE Default byte buffer size (8192, larger than that of ASCIIReader since it's reasonable to surmise that the average UCS-4-encoded file should be 4 times as large as the average ASCII-encoded file).
public static final short	UCS2LE
public static final short	UCS2BE
public static final short	UCS4LE
public static final short	UCS4BE
protected InputStream	fInputStream Input stream.
protected byte[]	fBuffer Byte buffer.
protected short	fEncoding

Constructors Summary
public UCSReader(InputStream inputStream, short encoding) Constructs an ASCII reader from the specified input stream using the default buffer size. The Endian-ness and whether this is UCS-2 or UCS-4 needs also to be known in advance. param inputStream The input stream. param encoding One of UCS2LE, UCS2BE, UCS4LE or UCS4BE. // // Constructors // this(inputStream, DEFAULT_BUFFER_SIZE, encoding);
public UCSReader(InputStream inputStream, int size, short encoding) Constructs an ASCII reader from the specified input stream and buffer size. The Endian-ness and whether this is UCS-2 or UCS-4 needs also to be known in advance. param inputStream The input stream. param size The initial buffer size. param encoding One of UCS2LE, UCS2BE, UCS4LE or UCS4BE. fInputStream = inputStream; fBuffer = new byte[size]; fEncoding = encoding;

Methods Summary
public void	close() 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 fInputStream.close();
public void	mark(int readAheadLimit) 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 fInputStream.mark(readAheadLimit);
public boolean	markSupported() Tell whether this stream supports the mark() operation. return fInputStream.markSupported();
public int	read() 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. return The character read, as an integer in the range 0 to 127 (0x00-0x7f), or -1 if the end of the stream has been reached exception IOException If an I/O error occurs int b0 = fInputStream.read() & 0xff; if (b0 == 0xff) return -1; int b1 = fInputStream.read() & 0xff; if (b1 == 0xff) return -1; if(fEncoding >=4) { int b2 = fInputStream.read() & 0xff; if (b2 == 0xff) return -1; int b3 = fInputStream.read() & 0xff; if (b3 == 0xff) return -1; System.err.println("b0 is " + (b0 & 0xff) + " b1 " + (b1 & 0xff) + " b2 " + (b2 & 0xff) + " b3 " + (b3 & 0xff)); if (fEncoding == UCS4BE) return (b0<<24)+(b1<<16)+(b2<<8)+b3; else return (b3<<24)+(b2<<16)+(b1<<8)+b0; } else { // UCS-2 if (fEncoding == UCS2BE) return (b0<<8)+b1; else return (b1<<8)+b0; }
public int	read(char[] ch, int offset, int length) 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 int byteLength = length << ((fEncoding >= 4)?2:1); if (byteLength > fBuffer.length) { byteLength = fBuffer.length; } int count = fInputStream.read(fBuffer, 0, byteLength); if(count == -1) return -1; // try and make count be a multiple of the number of bytes we're looking for if(fEncoding >= 4) { // BigEndian // this looks ugly, but it avoids an if at any rate... int numToRead = (4 - (count & 3) & 3); for(int i=0; i<numToRead; i++) { int charRead = fInputStream.read(); if(charRead == -1) { // end of input; something likely went wrong!A Pad buffer with nulls. for (int j = i;j<numToRead; j++) fBuffer[count+j] = 0; break; } else { fBuffer[count+i] = (byte)charRead; } } count += numToRead; } else { int numToRead = count & 1; if(numToRead != 0) { count++; int charRead = fInputStream.read(); if(charRead == -1) { // end of input; something likely went wrong!A Pad buffer with nulls. fBuffer[count] = 0; } else { fBuffer[count] = (byte)charRead; } } } // now count is a multiple of the right number of bytes int numChars = count >> ((fEncoding >= 4)?2:1); int curPos = 0; for (int i = 0; i < numChars; i++) { int b0 = fBuffer[curPos++] & 0xff; int b1 = fBuffer[curPos++] & 0xff; if(fEncoding >=4) { int b2 = fBuffer[curPos++] & 0xff; int b3 = fBuffer[curPos++] & 0xff; if (fEncoding == UCS4BE) ch[offset+i] = (char)((b0<<24)+(b1<<16)+(b2<<8)+b3); else ch[offset+i] = (char)((b3<<24)+(b2<<16)+(b1<<8)+b0); } else { // UCS-2 if (fEncoding == UCS2BE) ch[offset+i] = (char)((b0<<8)+b1); else ch[offset+i] = (char)((b1<<8)+b0); } } return numChars;
public boolean	ready() 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 return false;
public void	reset() 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 fInputStream.reset();
public long	skip(long n) 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 // charWidth will represent the number of bits to move // n leftward to get num of bytes to skip, and then move the result rightward // to get num of chars effectively skipped. // The trick with &'ing, as with elsewhere in this dcode, is // intended to avoid an expensive use of / that might not be optimized // away. int charWidth = (fEncoding >=4)?2:1; long bytesSkipped = fInputStream.skip(n<<charWidth); if((bytesSkipped & (charWidth | 1)) == 0) return bytesSkipped >> charWidth; return (bytesSkipped >> charWidth) + 1;