stringconverter.java

Java写的含有一个jdbc驱动的小型数据库数据库引擎

/*
 * StringConverter.java
 *
 * Copyright (c) 2001, The HSQL Development Group
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 *
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 *
 *
 * Neither the name of the HSQL Development Group nor the names of its
 * contributors may be used to endorse or promote products derived from this
 * software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * This package is based on HypersonicSQL, originally developed by Thomas Mueller.
 *
 */
package org.hsqldb;

import java.sql.*;
import java.io.*;

/**
 * Class declaration
 *
 *
 * @version 1.0.0.1
 */
class StringConverter {
    private static final char   HEXCHAR[] = {
	'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd',
	'e', 'f'
    };
    private static final String HEXINDEX = "0123456789abcdef          ABCDEF";

    /**
     * Method declaration
     *
     *
     * @param s
     *
     * @return
     */
    public static byte[] hexToByte(String s) {
	int  l = s.length() / 2;
	byte data[] = new byte[l];
	int  j = 0;

	for (int i = 0; i < l; i++) {
	    char c = s.charAt(j++);
	    int  n, b;

	    n = HEXINDEX.indexOf(c);
	    b = (n & 0xf) << 4;
	    c = s.charAt(j++);
	    n = HEXINDEX.indexOf(c);
	    b += (n & 0xf);
	    data[i] = (byte) b;
	}

	return data;
    }

    /**
     * Method declaration
     *
     *
     * @param b
     *
     * @return
     */
    static String byteToHex(byte b[]) {
	int	     len = b.length;
	StringBuffer s = new StringBuffer();

	for (int i = 0; i < len; i++) {
	    int c = ((int) b[i]) & 0xff;

	    s.append(HEXCHAR[c >> 4 & 0xf]);
	    s.append(HEXCHAR[c & 0xf]);
	}

	return s.toString();
    }

    /**
     * Method declaration
     *
     *
     * @param s
     *
     * @return
     */
    static String unicodeToHexString(String s) {
	ByteArrayOutputStream bout = new ByteArrayOutputStream();
	DataOutputStream      out = new DataOutputStream(bout);

	try {
	    out.writeUTF(s);
	    out.close();
	    bout.close();
	} catch (IOException e) {
	    return null;
	}

	return byteToHex(bout.toByteArray());
    }

    /**
     * Method declaration
     *
     *
     * @param s
     *
     * @return
     */
    public static String hexStringToUnicode(String s) {
	byte[]		     b = hexToByte(s);
	ByteArrayInputStream bin = new ByteArrayInputStream(b);
	DataInputStream      in = new DataInputStream(bin);

	try {
	    return in.readUTF();
	} catch (IOException e) {
	    return null;
	}
    }

    /**
     * Method declaration
     *
     *
     * @param s
     *
     * @return
     */
    public static String unicodeToAscii(String s) {
	if (s == null || s.equals("")) {
	    return s;
	}

	int	     len = s.length();
	StringBuffer b = new StringBuffer(len);

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

	    if (c == '\\') {
		if (i < len - 1 && s.charAt(i + 1) == 'u') {
		    b.append(c);    // encode the \ as unicode, so 'u' is ignored
		    b.append("u005c");    // splited so the source code is not changed...
		} else {
		    b.append(c);
		}
	    } else if ((c >= 0x0020) && (c <= 0x007f)) {
		b.append(c);    // this is 99%
	    } else {
		b.append("\\u");
		b.append(HEXCHAR[(c >> 12) & 0xf]);
		b.append(HEXCHAR[(c >> 8) & 0xf]);
		b.append(HEXCHAR[(c >> 4) & 0xf]);
		b.append(HEXCHAR[c & 0xf]);
	    }
	}

	return b.toString();
    }

    /**
     * Method declaration
     *
     *
     * @param s
     *
     * @return
     */
    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 - 1) {
		b[j++] = c;
	    } else {
		c = s.charAt(++i);

		if (c != 'u' || i == len - 1) {
		    b[j++] = '\\';
		    b[j++] = c;
		} else {
		    int k = (HEXINDEX.indexOf(s.charAt(++i)) & 0xf) << 12;

		    k += (HEXINDEX.indexOf(s.charAt(++i)) & 0xf) << 8;
		    k += (HEXINDEX.indexOf(s.charAt(++i)) & 0xf) << 4;
		    k += (HEXINDEX.indexOf(s.charAt(++i)) & 0xf);
		    b[j++] = (char) k;
		}
	    }
	}

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

    /**
     * Method declaration
     *
     *
     * @param x
     *
     * @return
     *
     * @throws SQLException
     */
    public static String InputStreamToString(InputStream x)
	    throws SQLException {
	InputStreamReader in = new InputStreamReader(x);
	StringWriter      write = new StringWriter();
	int		  blocksize = 8 * 1024;    // todo: is this a good value?
	char		  buffer[] = new char[blocksize];

	try {
	    while (true) {
		int l = in.read(buffer, 0, blocksize);

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

		write.write(buffer, 0, l);
	    }

	    write.close();
	    x.close();
	} catch (IOException e) {
	    throw Trace.error(Trace.INPUTSTREAM_ERROR, e.getMessage());
	}

	return write.toString();
    }

}