chartobyteunicode.java

来自「This is a resource based on j2me embedde」· Java 代码 · 共 157 行

/*
 * @(#)CharToByteUnicode.java	1.19 06/10/10
 *
 * Copyright  1990-2008 Sun Microsystems, Inc. All Rights Reserved.  
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER  
 *   
 * This program 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.   
 *   
 * This program 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 at /legal/license.txt).   
 *   
 * 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 or visit www.sun.com if you need additional  
 * information or have any questions. 
 *
 */

package sun.io;
import java.io.*;


/**
 * Convert arrays containing Unicode characters into arrays of bytes, using the
 * platform-default byte order.
 *
 * @version 	1.13, 00/02/02
 * @author	Mark Reinhold
 */

public class CharToByteUnicode extends CharToByteConverter {

    static final char BYTE_ORDER_MARK = (char) 0xfeff;
    protected boolean usesMark = true;      /* A mark should be written */
    private boolean markWritten = false;  /* A mark has been written */

    static final int UNKNOWN = 0;
    static final int BIG = 1;
    static final int LITTLE = 2;
    protected int byteOrder = UNKNOWN;

    public CharToByteUnicode() {
	String enc = (String) java.security.AccessController.doPrivileged(
           new sun.security.action.GetPropertyAction("sun.io.unicode.encoding",
							  "UnicodeBig"));
	if (enc.equals("UnicodeBig"))
	    byteOrder = BIG;
	else if (enc.equals("UnicodeLittle"))
	    byteOrder = LITTLE;
	else
	    byteOrder = BIG;
    }

    public CharToByteUnicode(int byteOrder, boolean usesMark) {
	this.byteOrder = byteOrder;
	this.usesMark = usesMark;
    }

    public CharToByteUnicode(boolean usesMark) {
        this();
        this.usesMark = usesMark;
    }

    public String getCharacterEncoding() {
	switch (byteOrder) {
	case BIG:
	    return usesMark ? "UnicodeBig" : "UnicodeBigUnmarked";
	case LITTLE:
	    return usesMark ? "UnicodeLittle" : "UnicodeLittleUnmarked";
	default:
	    return "UnicodeUnknown";
	}
    }

    public int convert(char in[], int inOff, int inEnd,
		       byte out[], int outOff, int outEnd)
	throws ConversionBufferFullException, MalformedInputException
    {
	charOff = inOff;
	byteOff = outOff;

	if (inOff >= inEnd)
	    return 0;

	int inI = inOff,
	    outI = outOff,
	    outTop = outEnd - 2;

	if (usesMark && !markWritten) {
	    if (outI > outTop)
		throw new ConversionBufferFullException();
	    if (byteOrder == BIG) {
		out[outI++] = (byte) (BYTE_ORDER_MARK >> 8);
		out[outI++] = (byte) (BYTE_ORDER_MARK & 0xff);
	    }
	    else {
		out[outI++] = (byte) (BYTE_ORDER_MARK & 0xff);
		out[outI++] = (byte) (BYTE_ORDER_MARK >> 8);
	    }
	    markWritten = true;
	}

	if (byteOrder == BIG) {
	    while (inI < inEnd) {
		if (outI > outTop) {
		    charOff = inI;
		    byteOff = outI;
		    throw new ConversionBufferFullException();
		}
		char c = in[inI++];
		out[outI++] = (byte) (c >> 8);
		out[outI++] = (byte) (c & 0xff);
	    }
	}
	else {
	    while (inI < inEnd) {
		if (outI > outTop) {
		    charOff = inI;
		    byteOff = outI;
		    throw new ConversionBufferFullException();
		}
		char c = in[inI++];
		out[outI++] = (byte) (c & 0xff);
		out[outI++] = (byte) (c >> 8);
	    }
	}

	charOff = inI;
	byteOff = outI;
	return outI - outOff;
    }

    public int flush(byte in[], int inOff, int inEnd) {
	byteOff = charOff = 0;
	return 0;
    }

    public void reset () {
	byteOff = charOff = 0;
	markWritten = false;
    }

    public int getMaxBytesPerChar() {
	return 4;		/* To allow for writing the byte-order mark */
    }

}