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  /*
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements.  See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.
   * The ASF licenses this file to You under the Apache License, Version 2.0
   * (the "License"); you may not use this file except in compliance with
   * the License.  You may obtain a copy of the License at
   * 
   *      http://www.apache.org/licenses/LICENSE-2.0
  * 
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
 
 package org.apache.jasper.xmlparser;
 
 import java.io.Reader;

Reader for UCS-2 and UCS-4 encodings. (i.e., encodings from ISO-10646-UCS-(2|4)).

Author(s):
Neil Graham, IBM
Version:
$Id: UCSReader.java 515 2008-03-17 21:02:23Z jfrederic.clere@jboss.com $
 
 public class UCSReader extends Reader {
 
     private org.jboss.logging.Logger log=
         org.jboss.logging.Logger.getLoggerUCSReader.class );
     
     //
     // Constants
     //
 
    
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 int DEFAULT_BUFFER_SIZE = 8192;
 
     public static final short UCS2LE = 1;
     public static final short UCS2BE = 2;
     public static final short UCS4LE = 4;
     public static final short UCS4BE = 8;
 
     //
     // Data
     //
 
    
Input stream.
 
     protected InputStream fInputStream;

    
Byte buffer.
 
     protected byte[] fBuffer;
 
     // what kind of data we're dealing with
     protected short fEncoding;
 
     //
     // Constructors
     //
 
    
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.

Parameters:
inputStream The input stream.
encoding One of UCS2LE, UCS2BE, UCS4LE or UCS4BE.
 
     public UCSReader(InputStream inputStreamshort encoding) {
         this(inputStreamencoding);
     } // <init>(InputStream, short)
 
    
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.

Parameters:
inputStream The input stream.
size The initial buffer size.
encoding One of UCS2LE, UCS2BE, UCS4LE or UCS4BE.
 
     public UCSReader(InputStream inputStreamint sizeshort encoding) {
          = inputStream;
          = new byte[size];
          = encoding;
     } // <init>(InputStream,int,short)
 
     //
     // 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.

Returns:
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
Throws:
java.io.IOException If an I/O error occurs
    public int read() throws IOException { 
        int b0 = .read() & 0xff;
        if (b0 == 0xff)
            return -1;
        int b1 = .read() & 0xff;
        if (b1 == 0xff)
            return -1;
        if( >=4) {
            int b2 = .read() & 0xff;
            if (b2 == 0xff)
                return -1;
            int b3 = .read() & 0xff;
            if (b3 == 0xff)
                return -1;
            if (.isDebugEnabled())
                .debug("b0 is " + (b0 & 0xff) + " b1 " + (b1 & 0xff) + " b2 " + (b2 & 0xff) + " b3 " + (b3 & 0xff));
            if ( == )
                return (b0<<24)+(b1<<16)+(b2<<8)+b3;
            else
                return (b3<<24)+(b2<<16)+(b1<<8)+b0;
        } else { // UCS-2
            if ( == )
                return (b0<<8)+b1;
            else
                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.

Parameters:
ch Destination buffer
offset Offset at which to start storing characters
length Maximum number of characters to read
Returns:
The number of characters read, or -1 if the end of the stream has been reached
Throws:
java.io.IOException If an I/O error occurs
    public int read(char ch[], int offsetint lengththrows IOException {
        int byteLength = length << (( >= 4)?2:1);
        if (byteLength > .) {
            byteLength = .;
        }
        int count = .read(, 0, byteLength);
        if(count == -1) return -1;
        // try and make count be a multiple of the number of bytes we're looking for
        if( >= 4) { // BigEndian
            // this looks ugly, but it avoids an if at any rate...
            int numToRead = (4 - (count & 3) & 3);
            for(int i=0; i<numToReadi++) {
                int charRead = .read();
                if(charRead == -1) { // end of input; something likely went wrong!A  Pad buffer with nulls.
                    for (int j = i;j<numToReadj++)
                        [count+j] = 0;
                    break;
                } else {
                    [count+i] = (byte)charRead
                }
            }
            count += numToRead;
        } else {
            int numToRead = count & 1;
            if(numToRead != 0) {
                count++;
                int charRead = .read();
                if(charRead == -1) { // end of input; something likely went wrong!A  Pad buffer with nulls.
                    [count] = 0;
                } else {
                    [count] = (byte)charRead;
                }
            }
        }
        // now count is a multiple of the right number of bytes
        int numChars = count >> (( >= 4)?2:1);
        int curPos = 0;
        for (int i = 0; i < numCharsi++) {
            int b0 = [curPos++] & 0xff;
            int b1 = [curPos++] & 0xff;
            if( >=4) {
                int b2 = [curPos++] & 0xff;
                int b3 = [curPos++] & 0xff;
                if ( == )
                    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 ( == )
                    ch[offset+i] = (char)((b0<<8)+b1);
                else
                    ch[offset+i] = (char)((b1<<8)+b0);
            }
        }
        return numChars;
    } // 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.

Parameters:
n The number of characters to skip
Returns:
The number of characters actually skipped
Throws:
java.io.IOException If an I/O error occurs
    public long skip(long nthrows IOException {
        // 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 = ( >=4)?2:1;
        long bytesSkipped = .skip(n<<charWidth);
        if((bytesSkipped & (charWidth | 1)) == 0) return bytesSkipped >> charWidth;
        return (bytesSkipped >> charWidth) + 1;
    } // skip(long):long

    
Tell whether this stream is ready to be read.

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.
Throws:
java.io.IOException If an I/O error occurs
    public boolean ready() throws IOException {
	return false;
    } // ready()

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

Parameters:
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:
java.io.IOException If the stream does not support mark(), or if some other I/O error occurs
    public void mark(int readAheadLimitthrows IOException {
	.mark(readAheadLimit);
    } // 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:
java.io.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();
    } // 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:
java.io.IOException If an I/O error occurs
     public void close() throws IOException {
         .close();
     } // close()
// class UCSReader
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