stringconverter.java

hsql是很有名的嵌入式数据库

     *
     * @return Java Unicode string
     */
    public static String asciiToUnicode(byte[] s, int offset, int length) {

        if (length == 0) {
            return "";
        }

        char[] b = new char[length];
        int    j = 0;

        for (int i = 0; i < length; i++) {
            byte c = s[offset + i];

            if (c == '\\' && i < length - 5) {
                byte c1 = s[offset + i + 1];

                if (c1 == 'u') {
                    i++;

                    // 4 characters read should always return 0-15
                    int k = HEXINDEX.indexOf(s[offset + (++i)]) << 12;

                    k      += HEXINDEX.indexOf(s[offset + (++i)]) << 8;
                    k      += HEXINDEX.indexOf(s[offset + (++i)]) << 4;
                    k      += HEXINDEX.indexOf(s[offset + (++i)]);
                    b[j++] = (char) k;
                } else {
                    b[j++] = (char) c;
                }
            } else {
                b[j++] = (char) c;
            }
        }

        return new String(b, 0, j);
    }

    public static String asciiToUnicode(String s) {

        if ((s == null) || (s.indexOf("\\u") == -1)) {
            return s;
        }

        int    len = s.length();
        char[] b   = new char[len];
        int    j   = 0;

        for (int i = 0; i < len; i++) {
            char c = s.charAt(i);

            if (c == '\\' && i < len - 5) {
                char c1 = s.charAt(i + 1);

                if (c1 == 'u') {
                    i++;

                    // 4 characters read should always return 0-15
                    int k = HEXINDEX.indexOf(s.charAt(++i)) << 12;

                    k      += HEXINDEX.indexOf(s.charAt(++i)) << 8;
                    k      += HEXINDEX.indexOf(s.charAt(++i)) << 4;
                    k      += HEXINDEX.indexOf(s.charAt(++i));
                    b[j++] = (char) k;
                } else {
                    b[j++] = c;
                }
            } else {
                b[j++] = c;
            }
        }

        return new String(b, 0, j);
    }

    public static String readUTF(byte[] bytearr, int offset,
                                 int length) throws IOException {

        char[] buf = new char[length * 2];

        return readUTF(bytearr, offset, length, buf);
    }

    public static String readUTF(byte[] bytearr, int offset, int length,
                                 char[] buf) throws IOException {

        int bcount = 0;
        int c, char2, char3;
        int count = 0;

        while (count < length) {
            c = (int) bytearr[offset + count];

            if (bcount > buf.length - 4) {
                buf = (char[]) ArrayUtil.resizeArray(buf,
                                                     buf.length + length);
            }

            if (c > 0) {

                /* 0xxxxxxx*/
                count++;

                buf[bcount++] = (char) c;

                continue;
            }

            c &= 0xff;

            switch (c >> 4) {

                case 12 :
                case 13 :

                    /* 110x xxxx   10xx xxxx*/
                    count += 2;

                    if (count > length) {
                        throw new UTFDataFormatException();
                    }

                    char2 = (int) bytearr[offset + count - 1];

                    if ((char2 & 0xC0) != 0x80) {
                        throw new UTFDataFormatException();
                    }

                    buf[bcount++] = (char) (((c & 0x1F) << 6)
                                            | (char2 & 0x3F));
                    break;

                case 14 :

                    /* 1110 xxxx  10xx xxxx  10xx xxxx */
                    count += 3;

                    if (count > length) {
                        throw new UTFDataFormatException();
                    }

                    char2 = (int) bytearr[offset + count - 2];
                    char3 = (int) bytearr[offset + count - 1];

                    if (((char2 & 0xC0) != 0x80)
                            || ((char3 & 0xC0) != 0x80)) {
                        throw new UTFDataFormatException();
                    }

                    buf[bcount++] = (char) (((c & 0x0F) << 12)
                                            | ((char2 & 0x3F) << 6)
                                            | ((char3 & 0x3F) << 0));
                    break;

                default :

                    /* 10xx xxxx,  1111 xxxx */
                    throw new UTFDataFormatException();
            }
        }

        // The number of chars produced may be less than length
        return new String(buf, 0, bcount);
    }

    /**
     * Writes a string to the specified DataOutput using UTF-8 encoding in a
     * machine-independent manner.
     * <p>
     * @param      str   a string to be written.
     * @param      out   destination to write to
     * @return     The number of bytes written out.
     */
    public static int writeUTF(String str, HsqlByteArrayOutputStream out) {

        int strlen = str.length();
        int c,
            count  = 0;

        for (int i = 0; i < strlen; i++) {
            c = str.charAt(i);

            if (c >= 0x0001 && c <= 0x007F) {
                out.write(c);

                count++;
            } else if (c > 0x07FF) {
                out.write(0xE0 | ((c >> 12) & 0x0F));
                out.write(0x80 | ((c >> 6) & 0x3F));
                out.write(0x80 | ((c >> 0) & 0x3F));

                count += 3;
            } else {
                out.write(0xC0 | ((c >> 6) & 0x1F));
                out.write(0x80 | ((c >> 0) & 0x3F));

                count += 2;
            }
        }

        return count;
    }

    public static int getUTFSize(String s) {

        int len = (s == null) ? 0
                              : s.length();
        int l   = 0;

        for (int i = 0; i < len; i++) {
            int c = s.charAt(i);

            if ((c >= 0x0001) && (c <= 0x007F)) {
                l++;
            } else if (c > 0x07FF) {
                l += 3;
            } else {
                l += 2;
            }
        }

        return l;
    }

    /**
     * Using a Reader and a Writer, returns a String from an InputStream.
     */
    public static String inputStreamToString(InputStream x,
            int length) throws IOException {

        InputStreamReader in        = new InputStreamReader(x);
        StringWriter      writer    = new StringWriter();
        int               blocksize = 8 * 1024;
        char[]            buffer    = new char[blocksize];

        for (int left = length; left > 0; ) {
            int read = in.read(buffer, 0, left > blocksize ? blocksize
                                                           : left);

            if (read == -1) {
                break;
            }

            writer.write(buffer, 0, read);

            left -= read;
        }

        writer.close();

        return writer.toString();
    }

// fredt@users 20020130 - patch 497872 by Nitin Chauhan - use byte[] of exact size

    /**
     * Returns the quoted version of the string using the quotechar argument.
     * doublequote argument indicates whether each instance of quotechar
     * inside the string is doubled.<p>
     *
     * null string argument returns null. If the caller needs the literal
     * "NULL" it should created it itself <p>
     *
     * The reverse conversion is handled in Tokenizer.java
     */
    public static String toQuotedString(String s, char quoteChar,
                                        boolean extraQuote) {

        if (s == null) {
            return null;
        }

        int    count = extraQuote ? count(s, quoteChar)
                                  : 0;
        int    len   = s.length();
        char[] b     = new char[2 + count + len];
        int    i     = 0;
        int    j     = 0;

        b[j++] = quoteChar;

        for (; i < len; i++) {
            char c = s.charAt(i);

            b[j++] = c;

            if (extraQuote && c == quoteChar) {
                b[j++] = c;
            }
        }

        b[j] = quoteChar;

        return new String(b);
    }

    /**
     * Counts Character c in String s
     *
     * @param String s
     *
     * @return int count
     */
    static int count(final String s, final char c) {

        int pos   = 0;
        int count = 0;

        if (s != null) {
            while ((pos = s.indexOf(c, pos)) > -1) {
                count++;
                pos++;
            }
        }

        return count;
    }
}