javaUnicode字符转换

/**
 * Unicode字符集转换
 * 提取于JDK 1.5.0_08 java.util.Properties类的私有方法（loadConvert，saveConvert）
 * 
 * @date 2009-4-7 17:09
 */
public class CharacterSetToolkit {
	
	/**
     * 从 Unicode 码转换成编码前的特殊字符串。
     * @param in Unicode编码的字符数组。
     * @param off 转换的起始偏移量。
     * @param len 转换的字符长度。
     * @param convtBuf 转换的缓存字符数组。
     * @return 完成转换，返回编码前的特殊字符串。
     */
	/*
     * Converts encoded \uxxxx to unicode chars
     * and changes special saved chars to their original forms
     */
    public static String unicodeToString(char[] in, int off, int len, char[] convtBuf) {
        if (convtBuf.length < len) {
            int newLen = len * 2;
            if (newLen < 0) {
	        newLen = Integer.MAX_VALUE;
	    } 
	    convtBuf = new char[newLen];
        }
        char aChar;
        char[] out = convtBuf; 
        int outLen = 0;
        int end = off + len;

        while (off < end) {
            aChar = in[off++];
            if (aChar == '\\') {
                aChar = in[off++];   
                if(aChar == 'u') {
                    // Read the xxxx
                    int value=0;
		    for (int i=0; i<4; i++) {
		        aChar = in[off++];  
		        switch (aChar) {
		          case '0': case '1': case '2': case '3': case '4':
		          case '5': case '6': case '7': case '8': case '9':
		             value = (value << 4) + aChar - '0';
			     break;
			  case 'a': case 'b': case 'c':
                          case 'd': case 'e': case 'f':
			     value = (value << 4) + 10 + aChar - 'a';
			     break;
			  case 'A': case 'B': case 'C':
                          case 'D': case 'E': case 'F':
			     value = (value << 4) + 10 + aChar - 'A';
			     break;
			  default:
                              throw new IllegalArgumentException(
                                           "Malformed \\uxxxx encoding.");
                        }
                     }
                    out[outLen++] = (char)value;
                } else {
                    if (aChar == 't') aChar = '\t'; 
                    else if (aChar == 'r') aChar = '\r';
                    else if (aChar == 'n') aChar = '\n';
                    else if (aChar == 'f') aChar = '\f'; 
                    out[outLen++] = aChar;
                }
            } else {
	        out[outLen++] = (char)aChar;
            }
        }
        return new String (out, 0, outLen);
    }
    
    /**
     * 将字符串编码成 Unicode 。
     * @param theString 待转换成Unicode编码的字符串。
     * @param escapeSpace 是否忽略空格。
     * @return 返回转换后Unicode编码的字符串。
     */
    /*
     * Converts unicodes to encoded &#92;uxxxx and escapes
     * special characters with a preceding slash
     */
    public static String stringToUnicode(String theString, boolean escapeSpace) {
        int len = theString.length();
        int bufLen = len * 2;
        if (bufLen < 0) {
            bufLen = Integer.MAX_VALUE;
        }
        StringBuffer outBuffer = new StringBuffer(bufLen);

        for(int x=0; x<len; x++) {
            char aChar = theString.charAt(x);
            // Handle common case first, selecting largest block that
            // avoids the specials below
            if ((aChar > 61) && (aChar < 127)) {
                if (aChar == '\\') {
                    outBuffer.append('\\'); outBuffer.append('\\');
                    continue;
                }
                outBuffer.append(aChar);
                continue;
            }
            switch(aChar) {
		case ' ':
		    if (x == 0 || escapeSpace) 
			outBuffer.append('\\');
		    outBuffer.append(' ');
		    break;
                case '\t':outBuffer.append('\\'); outBuffer.append('t');
                          break;
                case '\n':outBuffer.append('\\'); outBuffer.append('n');
                          break;
                case '\r':outBuffer.append('\\'); outBuffer.append('r');
                          break;
                case '\f':outBuffer.append('\\'); outBuffer.append('f');
                          break;
                case '=': // Fall through
                case ':': // Fall through
                case '#': // Fall through
                case '!':
                    outBuffer.append('\\'); outBuffer.append(aChar);
                    break;
                default:
                    if ((aChar < 0x0020) || (aChar > 0x007e)) {
                        outBuffer.append('\\');
                        outBuffer.append('u');
                        outBuffer.append(toHex((aChar >> 12) & 0xF));
                        outBuffer.append(toHex((aChar >>  8) & 0xF));
                        outBuffer.append(toHex((aChar >>  4) & 0xF));
                        outBuffer.append(toHex( aChar        & 0xF));
                    } else {
                        outBuffer.append(aChar);
                    }
            }
        }
        return outBuffer.toString();
    }
    
    /**
     * Convert a nibble to a hex character
     * @param	nibble	the nibble to convert.
     */
    private static char toHex(int nibble) {
	return hexDigit[(nibble & 0xF)];
    }
    
    /** A table of hex digits */
    private static final char[] hexDigit = {
	'0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F'
    };
}